Volume 2, Issue 1

This paper investigates the homo- and copolymerization of styrene with p -methylstyrene, m -methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene and 2,4,6-trimethylstyrene using a Cp*TiCl 3 (Cp: cyclopentadienyl) semimetallocene catalyst activated with methylaluminoxane. Syndiotactic homo- and copolymers were obtained only for the monosubstituted monomers. For the di- or trisubstituted monomers, reduced reactivities, stereoregularities, and degrees of polymerization were obtained with respect to the monosubstituted monomers. More specifically, the homopolymerization of 2,5-dimethylstyrene and 2,4,6-trimethylstyrene and their copolymerization with styrene was inhibited. The reason for this are combined steric and inductive effects. The presence of methyl groups in para position seems to inhibit crystallization of the syndiotactic polymers. In contrast, crystallinity was evidenced in the materials produced in the presence of m -methyl substituted monomers.

Enzymatic polymerization of m -substituted phenols has been achieved in the presence of 2,6-di- O -methyl-β-cyclodextrin (DM-β-CD) in a buffer. A watersoluble complex of the monomer and DM-β-CD was formed and polymerization was performed by peroxidase catalyst to give the polymer in high yields. Formation of the inclusion complex was confirmed by NOESY NMR. The association constant was determined by NMR and found to depend on the monomer structure.

A mixture of sodium nitrite and ascorbic acid is able to control the radical polymerization of tert -butyl methacrylate (tBMA) in water at 80°C. Indeed, sodium nitrite is reduced by the ascorbic acid, and the nitric oxide (NO) which is formed in situ is nothing but a promoter of nitroxyl radicals. The radical polymerization of tBMA is thus basically controlled by a nitroxide-mediated process.

Poly(styrene- block -methyl methacrylate)s were fully analyzed by liquid chromatography at the critical point of adsorption (LC-CC) and two-dimensional chromatography. Operating at chromatographic conditions corresponding to the critical points of the homopolymers polystyrene and poly(methyl methacrylate), the block lengths distributions for the different blocks of the block copolymers were determined quantitatively. Information on the amounts and molar mass distributions of homopolymers and coupling products that were identified in the samples as by-products was obtained by on-line coupled 2D chromatography. It was shown that a complete picture of the molecular heterogeneity of block copolymers can be obtained only when information from different chromatographic experiments is combined. Size exclusion chromatography alone is inappropriate for evaluating the molecular heterogeneity of such samples.

Phase separation occurs in thin films of polymer blends when molecular mobility is promoted by a temperature above the glass transition but inside the twophase region (temperature quench), or a common solvent added to the polymers (solvent quench). This phenomenon can be altered by a homogeneous surface or pre-patterned substrate, resulting, e.g., in self-stratification or pattern replication, respectively. Such self-organisation processes ordering polymer phases were observed for model polymer blends (deuterated/hydrogenated polystyrene, dPS/hPS, and deuterated/partially brominated PS, dPS/PBrS, both with hPSpolyisoprene diblocks added; dPS/poly(vinylpyridine) and PBrS/PVP) with highresolution ion beam techniques (Nuclear Reaction Analysis, profiling and mapping mode of dynamic Secondary Ion Mass Spectrometry) and Atomic Force Microscopy. The self-stratification process is strongly affected by both the range as well as the strength of the surface/polymer interactions. This is illustrated for the temperature-quenched blends with surface-active copolymer additives tuning the interactions exerted by both external surfaces. The pattern transfer from the substrate to the films is demonstrated for the solvent-quenched blends. Patterndirected composition variations (SIMS maps) coincide with free surface undulations (AFM images). The most effective pattern replication is achieved for the length scale of phase domain morphology comparable with the pattern periodicity and for carefully adjusted polymer/substrate interactions.

Films of polymers comprising the quasi-one-dimensional compounds K 2 [Pt(CN) 4 ]Br 0.3 , [Pt(NH 3 ) 4 ][PtCl 4 ] (Magnus’ green salt), or [Pt(NH 2 Oc) 4 ][PtCl 4 ] (Oc = octyl) were prepared from homogeneous solutions followed by solvent evaporation. Above a percolation threshold of ca. 8 - 10% v/v, the composites adopted the semiconductor behavior of K 2 [Pt(CN) 4 ]Br 0.3 or Magnus’ green salt, respectively. In the case of Pt(NH 2 Oc) 4 ][PtCl 4 ], a network established in the gel state in organic solvents was retained in the composites. Upon orientation of the composites by drawing, dichroism of the materials comprising Magnus’ green salt and polarized light emission with K 2 [Pt(CN) 4 ]Br 0.3 was observed.

Poly(4-vinylphenol- co -methyl methacrylate) (P(VPh-MMA)) and poly( N vinylpyrrolidone- co -vinyl acetate) (P(VPr-VAc)) form hydrogen bonding complexes with approx. 1:1 stoichiometry between the VPh unit of P(VPh-MMA) and the VPr unit of P(VPr-VAc) in methanol. These complexes show much higher glass transition temperatures than average polymer blends, suggesting the presence of extremely strong hydrogen bonds. FTIR measurements revealed selective hydrogen bonds between the hydroxy group of VPh units in P(VPh-MMA) and the carbonyl group of VPr units in P(VPr-VAc).

This short communication describes synthesis, optical and electronic properties of novel 9,9-dialkylfluorene- co -fluorenone copolymers which function as model systems for degradation-induced changes in polyfluorene-type semiconducting materials. Only very small fractions of incorporated fluorenone building blocks lead to a dramatic change of the solid state properties (photo- and electroluminescence). The results are discussed in terms of intra- vs. intermolecular excitation energy transfer.

A porous PMMA material has been reinforced by clay particles, and properties of the resulting material were evaluated. The clay has been intercalated in a first step by melt-extrusion with a suitable block copolymer. A radical polymerisation reaction after swelling of the intercalated clay with monomer leads in a subsequent step to a nanocomposite material with improved mechanical properties. The optimum load of modified clay was determined to be about 3 to 4 wt.-%. A separation of the reinforcing mineral into single sheets and a subsequent homogeneous incorporation of these sheets into the polymer matrix material increased different mechanical properties by approximately 60%. The lifetime of porous polymer moulds used for pressure casting of sanitary ware has been analysed, modelled and increased. The mechanical behaviour of the existing porous PMMA mould material was analysed using mechanical tests to assess the lifetime under cyclic loading. The relevant stress levels were obtained through in situ strain gauge measurements on a polymer mould for the production of a washing basin. These results were confirmed by means of finite element stress analyses. The lifetime of the washing basin mould under the relevant production conditions was predicted from these data and found to be in good agreement with practical experience. A method to improve the limited lifetime under higher pressures was developed by applying nanodispersed clay as reinforcement. The improved material shows an increase in lifetime under cycling loading by about 1000% in mechanical tests. This improvement is confirmed for a pressure casting mould made of the improved material when used in the actual production process.

Properties of two types of polystyrene microspheres with polyacrolein and polyglycidol components in their surface layers are compared. Microspheres were prepared in batch radical emulsifier-free emulsion copolymerizations of styrene with acrolein and/or α- tert -butoxy-ω-vinylbenzyl-polyglycidol macromonomer ( Mn̅ = 2700). Polymerizations were initiated with potassium peroxodisulfate, and the ratio of initial concentrations of styrene and initiator was constant. Number average diameters of poly(styrene/acrolein) (P(S/A)) and of poly(styrene/polyglycidol) (P(S/PGL)) particles were in the range of 200 - 650 nm and decreased with increasing concentration of acrolein and/or polyglycidol in the polymerizing mixtures. The diameter polydispersity of synthesized particles ( D w ̅ /D n ̅) was usually lower than 1.02. X-ray photoelectron spectroscopy for P(S/A) and P(S/PGL) microspheres showed that surface layers of particles were significantly enriched in polyacrolein or polyglycidol segments, surface fractions of which increased with increasing concentration of the more hydrophilic comonomer in the polymerizing mixture. In the case of P(S/A) particles, the maximal fraction of polyacrolein approached 80 mol-%, whereas for P(S/PGL) particles the maximal surface fraction of PGL was 42 mol-%. Human serum albumin was used as a model protein for studies of attachment onto P(S/A) and P(S/PGL) microspheres. It has been found that for both kinds of particles, the maximal surface concentration of attached (adsorbed and/or covalently immobilized) protein decreased with increasing fraction of hydrophilic component in the particle surface layer (polyacrolein or polyglycidol units). In the case of P(S/A) particles, adsorption always accompanied covalent immobilization of proteins. To the contrary, covalent immobilization of proteins onto the P(S/PGL) microspheres proceeded without adsorption of proteins.

After some comments on the size and conformation of dendrimer molecules, models of the polymerisation of AB 2 monomers that leads to hyperbranched polymers are reviewed. The models are (i) a kinetic one that takes into account changes in the reactivity of B groups as well as intramolecular reactions, and (ii) the equivalent Monte-Carlo model. The results of application of the kinetic model to the polymerisation system AB 2 + B 3 are also presented.

Polystyrene radicals (PS • ) were produced in high concentration using ω -bromopolystyrene (PS-Br) and α , ω -dibromopolystyrene (Br-PS-Br) in conjunction with Cu(I)Br following the atom transfer technique. A proper choice of the activator system led the PS-Br adduct to a maximum extent of coupling (by recombination), q max = 0.91, as estimated by gel permeation chromatography. On the other hand, the fraction of chains terminated by disproportionation was estimated to be 0.07 ± 0.04 by 1 H NMR. When the radical concentration [PS • ] was not high enough, the chain transfer reaction competed with termination, and q max remained low. For the bifunctional adduct Br-PS-Br, the coupling reaction produced ‘polymers’ of a variety of chain lengths, whose distribution obeyed the theory of random coupling, when q was lower than about 0.5. The high extent of coupling ( q max ≈ 0.9) achievable in short time (< 10 min) suggests practical applicability of this reaction.

Existing approaches to simulate the bubble growth/collapse in viscoelastic liquids use the integral form of a constitutive equation, that can additionally be analytically integrated over the radial domain. Here we represent the process by a system of simultaneous partial differential equations, with fixed and finite boundaries. This enables a direct computer implementation with commercially available software, with little additional programming effort. The involved co-ordinate transformation preferably does not correspond to the material co-ordinates. The surrounding liquid can be simulated as being a finite film or of infinite extent, with simply a change in one computational parameter. We simulate hydrodynamically induced bubble dynamics in viscolelastic liquids, and estimate the flow strength (elongational strain rate) and its possible role in flow induced scission of polymer chains in liquids experiencing bubble collapse. Calculations are also performed to evaluate the influence of backbone and branch lengths when the surrounding fluid is a branched polymer melt, using the pom-pom model to describe the rheological behavior.

A new polyethylene-compatible terthiophene chromophore, 5”-thio-(3- butyl)nonyl-2,2’:5’,2”-terthiophene, with melting point lower than 0°C was prepared and used for linear polarizers based on ultra-high-molecular-weight polyethylene (UHMWPE). Differential scanning calorimetry and scanning electron microscopy indicate that the new chromophore is dispersed uniformly in films of UHMWPE obtained by casting from solution. The films show excellent dichroic properties (dichroic ratio 30) at rather low drawing ratio (≈ 20) . Moreover, qualitative agreement is observed with the Ward pseudo-affine deformation scheme.

Two kinds of hyperbranched polymers, star-shaped poly(ethylene oxide) and poly(2-ethyl-2-oxazoline)-bound polyamidoamine dendrimer, were immobilized on polyurethane (PU) films using photoreactive azidophenyl groups. Immobilization of the hyperbranched polymers was verified by ATR FT-IR observations and contact angle measurements. Using photoreactive molecules, this study shows a unique method to modify polymer films without functional groups easily through immobilization of other polymers on the film surface. PU surfaces modified with immobilized hyperbranched polymer showed significantly reduced platelet adhesion, i.e. increased blood compatibility, as measured via UV spectrometry and scanning electron microscopy.

The application of time-resolved FTIR spectroscopy to investigate diffusion processes in polymers is described. Two thermosetting systems have been studied: a tetrafunctional epoxy resin cured with an aromatic diamine hardener, and a ternary formulation comprising the above components plus a bismaleimide co-monomer. Spectroscopic monitoring of water diffusion, both in the Mid and in the Near IR frequency ranges, yielded accurate and reproducible kinetic curves from which it was possible to evaluate the absolute parameters of diffusion (diffusivity and activation energy). These were found to compare favourably with the values obtained by conventional gravimetric methods. The molecular interactions between the penetrant molecules and the polymer networks were also investigated and it was shown that, in the system containing the bismaleimide component, the fraction of water molecules hydrogen-bonded to the network decreases significantly.

Flow alignment in a large amplitude oscillatory shear field of lamellar AB and ABC block copolymers has been studied in bulk and in solution. Flow birefringence and 2D small-angle X-ray scattering were used to monitor the orientation. Qualitatively similar orientation behaviour was found for the diluted and the bulk AB block copolymer. While in AB diblock copolymers there is only one interface between the different blocks which may influence the orientation behaviour, in ABC triblock copolymers there are two interfaces within the macromolecule. It will be shown that the introduction of a third block leads to a quite different orientation behaviour in comparison to the AB system. In the lamellar diluted ABC system always the parallel orientation dominates, but it occurs in coexistence with the perpendicular and transverse orientations.

The synthesis and free radical polymerization of a methacrylamide monomer, 5, bearing non-covalently attached cyclodextrins and the chalcone function with a barrier group, is described. The first step of preparation of the monomer was the condensation of 4-( N -methacryloyl-6-aminohexanoylamino)- acetophenone, 1 , with 4-nitrobenzaldehyde. The resulting 1-( N -methacryloyl-6- aminohexanoyl-4-aminophenyl)-3-(4-nitrophenyl)-2-propen-1-one, 2 , was reduced with tin(II) chloride dihydrate to the corresponding 1-( N -methacryloyl-6-aminohexanoyl- 4-aminophenyl)-3-(4-aminophenyl)-2-propen-1-one, 3 . After this, the aminochalcone was condensed with a barrier group, triphenylacetyl chloride, yielding 1-( N -methacryloyl-6-aminohexanoyl-4-aminophenyl)-3-( N’ -triphenylacetyl- 4-aminophenyl)-2-propen-1-one, 4 . Monomer 4 was copolymerized with methyl methacrylate to the model polymer poly[ 4 -co- methyl methacrylate], 6 , and also complexed with dimethylated β - cyclodextrin to the semi-rotaxane ( 4 / 2,6-Me2-β - CD) 5 , which was copolymerized with methyl methacrylate, yielding a polyrotaxane ( 5 - co- methyl methacrylate) 7 , containing a cyclodextrin ring in the side-chain. The semi-rotaxane 5 and both copolymers 6 and 7 were characterized spectroscopically and also by means of differential scanning calorimetry, gel permeation chromatography and thermogravimetrical analysis, and - in the case of 5 - by mass spectrometry. Furthermore, the UV-induced E/Z -isomerization of both polymers 6 and 7 was examined in tetrahydrofuran solution. A retarding effect of the noncovalently attached cyclodextrin was finally detected.

Development of biaxial segmental orientation and stresses in flexible chain polymers subjected to affine deformation of end-to-end vectors or to steady biaxial extensional flow is discussed. A closed-formula theory with non-Gaussian chain statistics and a Padè approximation of the inverse Langevin function is considered. The approach accounts for finite chain extensibility and is free from the problems of weak convergence of series-expansion expressions at higher molecular deformations. Average orientation tensor, global anisotropy tensor, and axial orientation factors characterise segmental orientation. Axial orientation factors and normal stress differences, in the deformation and normal planes, are discussed for biaxial affine deformation and steady biaxial elongational flow in a wide range of molecular deformations using inverse Langevin chain statistics. Orientation characteristics predicted for biaxial flow deformation are higher, and change in a wider range, than those in affine biaxial stretch. Also sensitivity to transversal deformation is different in both types of deformation.

The morphology of micelles formed by two poly(2-vinylpyridine)- block poly( ethylene oxide) (P2VP- b -PEO) copolymers has been studied in phosphatebuffered water by dynamic light scattering and transmission electron microscopy. Spherical micelles are observed when the P2VP block is the minor component of the diblock copolymer. When P2VP dominates the composition, transition from spheres-to-rods-to-vesicles takes place in a narrow pH range that straddles the p K a of P2VP. This transition is controlled by the degree of protonation of the P2VP blocks. At high pH, the copolymer precipitates from the solution.

The kinetics and the extent of side reactions of the anionic polymerization of silyl-protected 2-hydroxyethyl methacrylate, 2-( tert -butyldimethylsilyloxy)ethyl methacrylate (TBDMS-HEMA), in tetrahydrofuran (THF) were studied as a function of polymerization temperature. Lithium chloride was added in order to achieve a controlled polymerization. The results of polymerizations at various temperatures are compared with reported data for methyl methacrylate and tert -butyl methacrylate in THF. The activation energy for the studied monomer is lower compared to the other methacrylates. Gel permeation chromatography-viscosity studies show that poly(TBDMS-HEMA) exhibits a more wormlike structure in THF than other polymethacrylates, as indicated by a higher Mark-Houwink exponent, α = 1.025.

Bifunctional polybases of the partially quaternized poly[thio-1-( N , N diethylaminomethyl) ethylene] type (Q(PTDAE), X , with X = percentage of N-quaternization) are able to catalyze various reactions including lipophilic reagents temporarily entrapped in the hydrophobic core of the globules. In this contribution it is shown that benzyloxycarbonyl (Z) and fluoromethyloxycarbonyl (Fmoc) protecting groups of peptides are cleaved at room temperature in a few minutes in an aqueous medium at pH 7,4. Deprotection was also effective when peptides were attached to solid supports of the Merrifield type provided a hydrophilic spacer arm of the poly(ethylene glycol)-type was inserted between beads and the built up peptide moieties. However, unhooking was observed when the hydrophilic spacerpeptide bond was an ester but not when it was of the amide type. The work shows that Q(PTDAE), X globules exhibit enzyme-like activity in a homogeneous aqueous medium and in heterogeneous systems as well.

In classic theories of polymer crystallisation, it is assumed that only the nuclei are in thermodynamic equilibrium with the melt. In Strobl's model of polymer crystallisation, a multi-step process is discussed. At the first intermediate states, the growing lamellar crystallites are assumed to be in equilibrium with the melt. After a stabilisation step, the lamella gains final stability. We have studied the stability of growing polymer lamellae by applying short temperature pulses. Changes in morphology were detected by simultaneous shear modulus measurements. The highest temperature reached during such temperature pulses was always below the final melting temperature. For poly(ε-caprolactone) (PCL) at 331 K it was found that temperature pulses of 4 K height and 300 s duration every 1 800 s prevented crystallisation totally. Lower pulses only slow down the crystallisation process. For syndiotactic polypropylene at 403 K, pulses of 14 K every 7 200 s were necessary to prevent crystallization. For PCL the kinetics of the crystallisation and stabilisation processes has been determined. A temperature pulse of 4 K height after 10 000 s isothermal crystallisation at 331 K totally destroys the already formed crystalline structures although the degree of crystallisation at this time is already 17%. With ongoing annealing time, the crystalline structure becomes more stable and the impact of the pulses decreases. After main crystallisation, when the crystallinity is basically constant, the amount of stable lamellae continuously increases. This indicates the occurrence of a significant stabilisation step after formation of the lamellae in PCL.

UV and thermal polymerisations of styrene were carried out in the presence of conventional ‘iniferters’. The mechanisms of the two methods were investigated and provided new insight into the livingness of the so-called iniferter technique. Chain extension polymerisations were performed using symmetrical iniferters to check the living character of this technique under UV and thermal polymerization conditions. In accordance with the work of Otsu, we have shown that polymerisation under UV irradiation initiated by iniferters proceeds via the classical iniferter living (controlled) mechanism. On the other hand, thermal polymerisations were predominantly controlled by the reversible additionfragmentation chain transfer (RAFT) mechanism.

Modification of the interface changes the viscoelastic response of crystalline polymer blends. For incompatible systems, usually one or more additional tan δ (mechanical loss) peaks appear which reflect the embrittlement of the material. Upon proper compatibilization, the additional peaks disappear and the material becomes tougher. The associated phenomena are explained and illustrated by a number of examples including polypropylene filled with calcium carbonate, polyethylene (PE) and polystyrene compatibilized blends, compatibilized blends of poly(ethylene terephthalate) (PET) with polyethylene as well as polyamide 6/polypropylene- graft -acrylic acid blends. Modes of deformation producing cavitation and cavity free deformation were applied to polymer blends in order to study the influence of molecular orientation and the presence of cavities. It is concluded that interfaces between blend components are weak elements of the blends even in the presence of a compatibilizer. Dynamic mechanical analysis (DMTA) evidenced the occurrence of interactions of the compatibilizer with blend components through temperature shift and intensity change of α, β and γ relaxation processes of polymer components. In oriented films of PET/high-density PE compatibilized blends, the chain segments in the amorphous phase of PET are oriented along machine direction. However, there is a significant anisotropy of chain packing in the plane perpendicular to the drawing direction - the pseudohexagonal packing of chain fragments being in register over the whole film. The PET amorphous phase exhibits anisotropy: DMTA studies show that the glass transition occurs at different temperatures while bending the film in different directions. The source of the ‘anisotropy’ in glass transition is the anisotropy of the amorphous phase: the pseudohexagonal packing and the orientation of chain segments. It is evident that the free volume and frozen fraction of the amorphous phase exhibit some degree of anisotropy. In highly compressed samples free of cavities, the glass transition temperature is shifted to higher temperature as compared to undeformed or drawn and cavitated blends. The shift is the result of high molecular orientation of the amorphous phase of matrix polymer and of the stabilization effect of unbroken interfaces in compressed samples.

Chiral poly( L -lactide)s end-capped with a novel terpyridine ligand are synthesized by a controlled coordinative polymerization procedure. The resulting well-characterized macroligands can be complexed under phase-transfer conditions with iron(II) ions to form well-defined supramolecular poly( L -lactide) complexes. The outstanding stability of such coordinative polymers enables the full characterization by gel permeation chromatography (GPC) and MALDI-TOF mass spectrometry. In addition, in-line diode array UV-Vis spectroscopy coupled to GPC was carried out to verify the formation of the poly(ester) complexes.

Hyperbranched polyesters containing labile triazene units in the main chain have been characterized according to their photochemically and thermally induced decomposition behavior. Irradiation with UV light results in a first order decomposition behavior with half-time of 6 to 48 min depending on the structure of the repeating unit. Thermal decomposition starts at about 160°C, and about 50% mass loss are achieved after 15 min at 250°C. Homogeneous incorporation of these globular, functional polymers in thermostable polymer matrices (polyimides and benzocyclobutane-based polymers) was possible. Smooth films from blends of thermostable matrix and up to 50% hyperbranched polymers could be prepared. The hyperbranched component could be destroyed selectively, and the resulting porous matrix has been studied as insulating material for microelectronic multilayer applications.

Interpenetrating polymer networks made of dicyclopentadiene and methyl methacrylate or tri(ethylene glycol) dimethacrylate have been successfully prepared by non-interfering frontal polymerization. The role of catalyst and free radical initiator relative amounts, as well as of monomer ratio, has been thoroughly studied. The conditions under which a pure frontal polymerization occurs, and the related values of both front velocity and maximum temperature reached by the reaction, are presented and discussed.

This is an analytical review on kinetics and mechanism of threedimensional radical polymerization (TDRP) of multifunctional vinyl monomers (oligomers) having two or more double bonds per molecule. The period (1960 - 1977) of establishing the fundamental kinetic law of TDRP and the principal characteristics of its mechanism, i.e., microheterogeneity, is briefly described. New intense progress in the field of TDRP (during the recent decade) resulting from the development of new technologies based on this technique (fiber-optic engineering, information technology, etc.) has received much consideration. The methodological peculiarities of investigations on TDRP kinetics and mechanism, which are a result of the complex conditions of highly structured reaction media inherent in TDRP processes, are described. Particular attention is given to techniques of structuralphysical investigation (a consistent complex of methods including ESR, NMR, diffusion and radiation probing, mechanics and thermomechanics) sensitive to structural microheterogeneity in the range 10 -6 - 10 -4 cm. The perspectives of macromolecular design based on TDRP data are analyzed including latest approaches as the employment of a ‘living’ chain mode. This review covers three monographs in Russian, reflecting three sequential stages of TDRP development from 1960 till 1995 using acrylic oligomers as an example (most of the investigations were carried out at the Institute of Chemical Physics RAS). The bibliography includes 197 references.

Poly( p -xylylene)s (PPX) with aliphatic substituents at the alpha position were synthesized by chemical vapor deposition (CVD) via vapor phase pyrolysis of α-chloro-1,4-xylenes, or by base-induced dehydrohalogenation of α-chloro-1,4- xylenes (Gilch route). These PPXs are soluble under ambient conditions in organic solvents. The glass transition temperature of the tert -butyl substituted PPX is remarkably high. Good thermal stability under nitrogen was observed for the trifluoromethyl substituted PPX. A functionalized compound suitable for polymer analogous reactions is the norbornenyl substituted PPX.

Pd-catalyzed Suzuki coupling is used to prepare poly( p -phenylene)s (PPPs) bearing oligo(ethylene oxide)s (OEOs) and trialkylamino groups as lateral substituents. The OEO substituents require very specific reaction conditions during monomer synthesis - presumably due to their coordinating oxygen atoms - but do not affect the subsequent Pd-catalyzed polycondensation process. In contrast to this, the lateral amino groups lower the degree of polycondensation of the PPPs considerably when their nitrogen atom is placed in the β-position of the side chains. When there is a longer spacer group between the amino nitrogen and the aromatic ring to be coupled, however, high-molecular-weight PPPs can be obtained. Provided an appropriate substitution pattern and long OEO side chains are used, the resulting PPPs are readily soluble not only in organic solvents but even in aqueous media. For one of these PPPs, the degree of protonation has been determined as a function of pH, using 1 H and 13 C NMR spectroscopy as well as potentiometry. It is shown that the polymer is completely deprotonated at pH > 10.5 and quantitatively protonated at pH < 4.0.

The kinetics of an interchain exchange reaction in homogeneous polymer blends is studied theoretically. A set of kinetic equations describing the evolution of the block weight distribution is derived. It is demonstrated that the process may be divided into a fast and a slow stage. The former results in the almost full disappearance of homopolymer chains. Simultaneously, the block weight distribution becomes close to the Flory distribution. In the course of the slow stage, the average block lengths decrease to values typical of a completely random copolymer. It is explicitly shown that for an initial blend of homopolymers characterized by the Flory distribution, the transient block weight distribution takes the Flory form starting from the onset of the reaction. The copolymer composition is proved to change in the course of the fast stage of the process. Previous attempts to address the problem are discussed.

Ring-opening polymerization (ROP) and ring-opening metathesis polymerization (ROMP) of an unsaturated ε-caprolactone, 6,7-dihydro-2(3 H )-oxepinone (DHO2), are alternative routes to produce unsaturated aliphatic polyesters with the same molecular structure. Polymerization of DHO2 initiated by Al isopropoxide in toluene at room temperature or at 0°C proceeds by a coordination-insertion mechanism, although intramolecular transesterification takes place beyond complete monomer conversion. The molecular weight distribution is narrow as long as monomer conversion does not exceed 90%. Ring-opening metathesis polymerization of DHO2 initiated by Schrock’s Mo-based catalyst, 1, at 60°C allows higher molecular weight unsaturated polyester to be prepared, even though an intramolecular side reaction also operates. The structure of poly(DHO2) synthesized by ROP and ROMP is the same, as confirmed by 1 H, 13 C NMR, and FT-IR spectra. Copolymers of DHO2 with norbornene, cis -cyclooctene, and 1,5-cyclooctadiene have been successfully prepared.

The morphology of micelles formed by two polystyrene- block -poly(2- vinylpyridine)- block -poly(ethylene oxide) (PS- b -P2VP- b -PEO) copolymers was studied in water by dynamic light scattering and transmission electron microscopy. Spherical micelles were observed that consist of a PS core, a P2VP shell and a PEO corona. The characteristic size of core, shell and corona depends on the copolymer composition. An important increase in micellar size occurs at pH < 5 as a result of P2VP block protonation. The reversibility of this pH effect depends on copolymer composition, too. The conformation of the PEO block plays an important role in this pH driven morphological transition.

Recent studies on organization and reorganization of polymer single crystals have contributed to the actual discussion on novel approaches towards understanding polymer crystallization and melting. In this context, low voltage scanning electron microscopy (LVSEM) and atomic force microscopy (AFM) demonstrate their importance for the investigation of polymer crystals. Both techniques are able to visualize the morphology of individual single crystals, which have a thickness in the order of 10 to 30 nm and a lateral size of a few micrometers, respectively, without any additional sample treatment such as coating or etching. Main advantage of LVSEM is its large range of observation: LVSEM is suited for fast screening and sample quality evaluation on the millimeter or micrometer level, and at the same time it has the prospect for detection of morphological details with nanometer resolution. The main strength of AFM is twofold: first, its excellent ability for precise quantitative thickness determination of the crystals, and second, using non-contact mode it can act as a non-destructive investigation technique, which allows in situ investigation of dynamic processes during sample treatment. By presenting some results of our studies, e.g., time dependent growth or temperature dependent annealing behavior of individual single crystals, we like to point out the specific advantages of the two techniques for fundamental studies on individual crystals, or ultra-thin polymer layers in general.

It has been established that the electroviscosity effect of polyzwitterionic (PZI) aqueous solutions is more considerable than and acts in a direction opposite to that of aqueous polyelectrolyte solutions. Temperature and electric field strength influence the electroviscosity of PZI aqueous solutions in parallel, though the reasons for these effects are quite different. The unusual electroviscosity behaviour of PZI solutions is explained by a ‘core-shell’ model for the structural organization of PZI macromolecules, suggesting that cluster formation is due to intensive dipoledipole interactions between monomer units of the same or of different macromolecules.

Temperature-dependent small-angle X-ray scattering spectroscopy of isothermally cold crystallized isotactic polystyrene revealed considerable morphological reorganization during subsequent heating to the melt. Both the crystalline thickness and the long period increased continuously with increasing temperature before the samples finally melted. The temperature dependence of these changes correlated very well with the melting behaviour observed with differential scanning calorimetry. As the temperature increased during a heating scan, the initial lamellae that formed during isothermal crystallization showed only little reorganization until they started to melt. Then, the molten material recrystallized continuously into increasingly thicker lamellae at increasing temperature until they finally melted. As the crystallization temperature approached the final melting temperature of the recrystallized lamellae, the initial lamellae melted without further recrystallization and no morphological changes were seen in this case.

The synthesis and characterization of N -methacryloyl- L -tyrosine methyl ester (3a) and ethyl ester ( 3b ), and their acetyl derivatives O -acetyl- N -methacryloyl- L -tyrosine methyl ester ( 4a ) and ethyl ester ( 4b ) are described. Monomers 3 and 4 were complexed with RAMEB (randomly methylated ß -cyclodextrin) yielding water soluble host-guest complexes 5a - d . The radical polymerization of monomers 3 and 4 was investigated in the presence as well as in the absence of RAMEB in aqueous medium at room temperature and also at 60°C. It is shown that the polymerization tendency of complexes 5a - d at room temperature is lower, leading to polymers of higher molecular weight, compared to the free monomers 3 and 4 . Furthermore, the polymerization of monomers 3 and 4 was carried out in homogenous organic solution using 2,2’-azoisobutyronitrile as initiator, and the results are discussed.

Semi-crystalline polymers like syndiotactic polypropylene pass during tensile deformation different stages with cross-overs at four critical points. Temperature variation above ambient changes the stresses at the critical points, but leaves the strains constant. Cooling down to the glass transition leads to the following changes: Fracture occurs before the onset of strain hardening. Yield point strain shifts to lower values. Young’s modulus increases by a factor on the order of the inverse of the crystallinity, as can be expected when the amorphous regions also contribute to the transmission of forces.

We report a comparison between optical properties (photoluminescence and UV-Vis absorption) and electroluminescence in a series of soluble polyalkylthiophenes with the aim of better understanding the role of different structural parameters, viz. length of side chains and introduction of unsubstituted thiophenes and their position in the backbone, on the electro-optical properties. The potential of these polymers as material for an active film in a single layer light emitting diode is evaluated.

A review of the results obtained for the birefringence of different supermolecular structures of three polymorphic forms of polypropylene is presented. All known lamellar super-molecular formations of the monoclinic, hexagonal and triclinic phases are included. The observed morphology varies among negative hedrite and oval structures with axial symmetry, spherulites and typical dendrites. An attempt to explain the observed variety of the various structures’ birefringence is made in terms of the mutual orientation of the polarizability ellipsoid and crystallographic axes in the lamellar surfaces. For the α phase, the orientation of the axes of the polarizability ellipsoid relative to the orientation of the unit cell is determined. The axis Nm coincides with the a axis, the fastest growth direction. The hedritic structures, grown by branching homoepitaxy, have negative birefringence. The spherulites differ in intensity and sign of birefringence because of cross-hatching. For the β phase, the crystallographic axis b coincides with Ne, the short axis of the rotational polarizability ellipsoid. The hedritic structures can grow by the screw dislocation mechanism. Spherulites grow by an epitaxy mechanism. Both structures show negative birefringence. The long axis Ng of the polarizability ellipsoid of the γ phase coincides with the b axis. The short molecules of the γ phase are inclined 40° towards the lamellar surface. The a and b axes do not lie in the lamellar surface. The axes of the polarizability ellipsoid are also inclined towards the lamellar surface. The preferred fast growth direction of the branching lamellae is the b * direction which coincides with Ng', the longest axis in the projection of the optical indicatrix on the lamellar surface. Thus the positive birefringence of the branching lamellae in the mixed α-γ spherulites increases more than in the monoclinic positive spherulites.

The copolymerization of isobutyl vinyl ether (IBVE) with methyl vinyl ether (MVE), initiated by the system 1,1-diethoxyethane/trimethylsilyl iodide/zinc iodide and conducted at 0°C in toluene, was found to be ‘living’ just as the homopolymerizations of these monomers. Monomer reactivity ratios are r IBVE = 1.08 and r MVE = 0.43. The lower critical solution temperature of polyMVE in water, situated around 37°C, was lowered to 10°C (for a 0.25 wt.-% solution) when 6 mol-% of IBVE units were introduced in copolymers of molar mass 3000 - 7000 g/mol. At higher IBVE contents, the polymers are insoluble in water at all temperatures.

Structure and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE) films of different draw ratios produced from gel-cast and meltcrystallised samples by multi-stage zone drawing have been studied in order to investigate the structural development and to clarify the role of interfaces between morphological units in the mechanical behaviour. The complex hierarchy of fibrillar structures generating upon neck formation is revealed. It is shown that the rearrangement of initial chain-folded crystallites into a microfibrillar structure occurs inside the volumes of supermolecular structures of larger sizes (spherulites in the melt-crystallised films and stacks of lamellae in the gel-crystallised films), the boundaries between the latter not having disappeared. Both the initial spherulites and stacks of lamellae with internally rearranged microfibrillar structure elongate upon drawing and comprise spindle-like units - macrofibrils - which are well resolved in scanning electron microscopy. Moreover, superfibrils have been revealed in the melt-crystallised films for the first time. They are, as suggested, the remnants of deformed and rearranged nascent polymer particles. Thus, the volume of the drawn films is considered to be full of interfaces. It is suggested that the majority of conformational defects, like chain ends, loops, tie molecules, entanglements, etc., are expelled from fibrillar crystallites in both intra- and interfibrillar regions. In addition to that, the interfibrillar spaces are crossed by tie molecules and micro- and macrofibrils. All of them hinder interfibrillar slip. The differences in creep and recovery of the investigated films are discussed in terms of density of packing and degree of connectivity of various scale fibrillar structural units. The lateral boundaries and the tips of fibrils are considered to be the weakest structural sites from which kink band formation and subsequent fracture of the loaded material begin.

Molybdenum carbene complexes supported on Al2O3/methylaluminoxane/ diol based carriers were tested in continuous metathesis reactions. For investigations on the stability of the heterogenized complexes, a small tubular reactor filled with catalyst powder was used. When mixing cyclic monomers with chain-transfer agents, we were able to run ring-opening metathesis polymerization (ROMP) via the supported carbenes in a continuous process. Furthermore, continuous acyclic metathesis reaction (ACM) and ring-closing metathesis reaction (RCM) were investigated. Results show that the stability of these molybdenum carbene complexes depends on the concentration of methylidene carbenes formed during the reactions.

The aim of this review is to provide evidence that rheological testing is a potent tool for characterising polymers in the melt. An effort has been made in order to gather results in conventional and model polyolefins, and correlating them with phenomena occurring at the molecular level. We have focused our interest on long chain branching (LCB). In the case of materials containing long side-chain branches, strong effects on viscosity, elastic character and activation energy of flow are general features. Literature results mostly indicate that the effect of polydispersity on these parameters could be very similar to that expected due to the presence of LCB - notwithstanding that the effects of LCB seem to be stronger than those due to polydispersity for a given molecular weight. Different relaxation processes appear as a consequence of the presence of LCB: slower terminal relaxation behaviour than of linear counterparts, and faster additional branch relaxation at higher frequencies, clearly distinguishable from polydispersity effects. To measure the amount of LCB from limited viscoelastic data and molecular properties seems to be a suitable instrument to explain the rheological features of the different polymers, but it fails when the results are compared with measured values of LCB density in model polymers. The actual framework leads us to say that the number of branches is less important than the topology itself. Therefore, the position and architecture of the branches along the polymer main chain are the main factors that control the rheology of the material.

Well-defined coordination polymers are described whose main chains are held together by pseudo-octahedral ruthenium(II) complexes in which five ligands are nitrogen and one ligand is carbon. In the first step of polymer synthesis, the bis-tridentate ligand 4,4''-bis[4'-(2,2':6',2''-terpyridine)]-2',5'-dihexyl- p -terphenyl is treated with two equivalents of ruthenium(III) chloride. The resulting dinuclear metal-monomer is subsequently activated by exchanging the remaining three chloro ligands at each ruthenium center by acetone as a more easily substitutable ligand. The activated metal monomer is treated with equimolar amounts of 4,4''- bis[4'-(6'-phenyl-2,2'-bipyridine)]-2',5'-dihexyl- p -terphenyl as a bis-tridentate ligand monomer. During this conversion, rodlike chains grow through the formation of two further metal-nitrogen bonds and one carbon-nitrogen bond at every ruthenium center. The homogeneous constitution of the readily soluble polymers is proven, and their degrees of polycondensation are roughly estimated to be P n ≥ 20, using 1 H and 13 C NMR spectroscopy. UV-vis absorption spectra show the polymers to behave like chains of electronically independent metal complexes. Due to the carbon-ruthenium bond, however, λmax appears at a longer wavelength (approx. 530 nm) than in the related coordination compounds with only nitrogen-ruthenium bonds. There, λ max is around 500 nm.

In free-radical olefin polymerization, polymer transfer reactions can lead to chain scission as well as to the formation of long-chain branches. The dimensions of branched polymers so formed are investigated theoretically, by focusing our attention on the effects of scission frequency that is often difficult to determine. Scission reactions decrease the weight-average molecular weight significantly. When the polymer molecules are fractionated by the degree of polymerization (DP), however, the averages of branching density P ρ ̅and the mean-square radius of gyration of polymers with DP = P , < s 2 > P , are essentially unchanged, as long as the scission frequency is not very large. In a simple relationship between the ratios g and g’ of radii of gyration and hydrodynamic radii, g’ = gb , the value of b may change as a function of DP, and a simplified model function b = A log P + B was used to investigate the elution curve of size exclusion chromatography (SEC). It is shown that, although the molecular weight distribution (MWD) calibrated relative to standard linear polymers in SEC is much narrower than the true MWD, the use of a light scattering photometer to determine the absolute weight-average molecular weight within the elution volume makes the obtained MWD very close to the true one. On the basis of the < s 2 > P vs. P relationship, the calibrated MWD can be converted reasonably well to the true MWD. This simplified transformation method can be applied without knowing the scission frequency or the DP dependence of b . Once the true MWD is successfully estimated, a reliable parameter for the scission reaction can be determined.

The thermal degradation process of some new polycarbonates is investigated from an experimental and theoretical point of view, in order to obtain insight into the microscopic aspects that influence the reaction mechanism and the process of thermolysis. In particular, attention is focussed on the influence of the type of substituents in the polymer chain on the degradation temperature. A series of novel polycarbonates were designed differing from each other by the groups attached at the α and β carbon atoms. Thermal behavior was characterized by thermogravimetrical analyses. The polymers undergo rapid and complete thermolysis at different degradation temperatures depending on the structure. The degradation products were separated by gas chromatography and analyzed by mass spectroscopy. The ratio of formed dienes in the product distribution depends on the heating rate. Furthermore, density functional theory calculations were performed on a series of model compound systems for the polycarbonates under study, in particular carbonate systems differing by the groups attached at the α and β carbons. The study proves that the thermal degradation route can be controlled by tailoring the polymer backbone structure. Moreover, ab initio calculations provide further insight into the microscopic ingredients that govern the degradation process and associated reaction rates.

The miscibility and interactions of poly(vinyl nitrate) (PVN) / poly(vinyl methyl ketone) (PVMK) and poly(ethylene- co -vinyl nitrate) (EVN) / PVMK blends were investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). PVN/PVMK blends were found to be miscible in the entire composition and temperature range. In addition, the compositional dependence of the glass transition temperature showed a positive deviation from the linear additivity rule, a phenomenon normally associated with compounds having attractive interactions. However, in this case, no attractive interactions between PVN and PVMK were identified by FTIR analyses. On the other hand, EVN/PVMK blends were found to be immiscible for most copolymer compositions, blend compositions and temperature ranges. Furthermore, intramolecular repulsive interactions of EVN were not apparent despite strong contrary expectations. Therefore, the phase behaviour in these blends was explained by a miscibility mechanism different from that of conventional polymer blends containing random copolymers.

New optically active 1,1-disubstituted 2-vinylcyclopropanes , 3a, b were synthesized by esterification of the corresponding 1-ethoxycarbonyl-2-vinylcyclopropane- 1-carboxylic acid 2a , b with cholesterol and characterized by 1 H NMR and IR spectroscopy. The liquid crystalline properties of the obtained monomers are reported. The effect of the structure of the 2-vinylcyclopropane monomers on the phase transition of the mesogen was investigated. Radical polymerization of the asymmetrically substituted monomers 3a , b in solution and in bulk resulted in liquidcrystalline polymers with 1,5-opened units, as evidenced by 1 H NMR spectroscopy.

Urease has been covalently immobilized on polypyrrole microspheres chemically linked to conducting polypyrrole-polyvinyl sulfonate (PPY-PVS) films. These films were electrochemically prepared during 5 - 7 min at a constant current of 2 mA using indium - tin oxide (ITO) glass plates as the working electrode, and a standard calomel electrode as the reference electrode. Urease covalently linked to polypyrrole microspheres (by reaction of protein amino groups with aldehyde groups on the surface of the microspheres) was entrapped/adsorbed onto electrochemically prepared conducting PPY-PVS films deposited on ITO. Potentiometric measurements undertaken on these conducting polymer electrodes using an ammonium ion analyzer reveal that they can be used for estimating the urea concentration in solutions from 5·10 -3 mol/l to 6·10 -2 mol/l.

Mesomorphic structures of hydrogen bridged poly(4-vinylphenol) - N , N -dimethyl- n-octadecylamine (PVPh-NDOA) and PVPh - N , N -dioctadecylmethylamine (PVPh-DOMA) mixtures were investigated by means of wide angle X-ray diffraction, small angle X-ray scattering, and IR spectroscopy. Octadecyl chains of the PVPh-NDOA and PVPh-DOMA mixtures showed hexagonal α H and orthorhombic β O packing, respectively. In addition, PVPh-NDOA and PVPh-DOMA formed lamellar structures with periods of 3.5 and 2.5 nm, respectively.

Porous polymeric films were obtained by immersing a solution of cellulose acetate and high molecular weight poly(acrylic acid) into an ice-water mixture. The films, the porosity of which can be controlled (reversibly) by immersion into hot water for varying periods of time, were characterized by IR spectroscopy and lowvacuum scanning electron microscopy.

Inorganic particles of 3 CaO ⋅ SiO 2 were reacted in water dispersion with dihydrophilic ionic-nonionic block copolymers, and the heat effect of interaction was measured by calorimetry. The ionic block was constituted of monoesters of phosphoric acid or alkyl phosphonic acid, both built on the polyglycidol block, attached to the poly(ethylene oxide) block. The heat evolved during the interaction is a function of the degree of phosphorylation (phosphonylation). The higher the degree of -OH substitution the stronger the interaction, the latter being stronger for phosphates than for phosphonates.

High performance thermoplastic poly( p -phenylene sulfide) (PPS) is commercially produced from sodium sulfide and p -dichlorobenzene: Na-S-Na + Cl-(C 6 H 4 )-Cl → -[C 6 H 4 S]- + 2 NaCl At a first glance, this looks like a classical step growth polymerization of the A-A + B-B type. There has been considerable discussion and scientific investigation about the reaction mechanism. Today, it is accepted that PPS polymerization is a step growth polymerization with chain length dependent end group reactivities. This paper suggests to add a polymer chain cleavage reaction to the known kinetic model in order to improve the fit of experimental observation and modeling results. Implications of this reaction kinetic model for the design and engineering of an optimized PPS polymerization process are discussed.

The frontal polymerization technique has been successfully applied, for the first time, to obtain an unsaturated polyester/styrene resin. The effect of the ratio of the two aforementioned components, as well as of the type and amount of free-radical initiator on both front velocity and maximum temperature reached by the front, has been thoroughly studied. The resulting products have been characterized in terms of their thermal and dynamic-mechanical behaviour. A comparison of such products with the corresponding materials obtained by the classical batch polymerization technique has evidenced that frontal polymerization allows to reach a higher degree of crosslinking with respect to batch copolymerization and hence a better thermal and mechanical behaviour.