Band 89, Heft 1

The cleaning of artifacts must not alter the original properties of the objects. While the use of free solvents is risky, their confinement into polymeric networks can allow the safe removal of unwanted layers from artifacts. Recently, a methyl 2-methylprop-2-enoate (MMA)-based organogel was formulated as loaded with butan-2-one (MEK), and used to remove aged varnishes from canvas paintings. However, this formulation is not enough retentive to allow its use on paper, where higher retentiveness is needed to avoid the uncontrolled spreading of MEK and dissolved materials. Here, a new PMMA-MEK gel was designed to overcome this limitation. The amount of cross-linker and monomer used in the synthesis of the gel were tuned to achieve optimal retentiveness. Differential scanning calorimetry (DSC), differential thermogravimetry (DTG), small-angle X-ray scattering (SAXS) and attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR) provided information on the solvent content, release rate, and mesoporosity of the gel as compared to the previous system. The lower solvent release rate of the new formulation allowed the safe removal of wax that jeopardized a 19 th century paper document. The removal was confirmed through optical microscopy and ATR-FTIR, which also highlighted the absence of gel residues on the treated surface.

A new PEG-containing liquid crystalline side chain block copolymer HBC-PEG550 was prepared from poly(ethylene glycol)-b-poly(2-(diethylamino) ethyl methacrylate copolymer (BC-PEG550) and 8-(4-cyanobiphenyl-4′-oxy) octan-1-ol (LC8) by molecular self-assembly processes via hydrogen bond formation between amine group of HBC-PEG550 and hydroxyl group of the LC8. The formation of H bond was confirmed by using FTIR spectroscopy. The liquid crystalline behavior of the HBC-PEG550 was investigated by differential scanning calorimeter (DSC) and polarized optical microscopy. Dielectric properties of HBC-PEG550 and HBC-PEG550 has been studied by impedance spectroscopy. Real and imaginary parts of complex dielectric constant, impedance, and energy loss tangent factor for HBC-PEG550 and HBC-PEG550 have been characterized in the frequency range of 100 Hz–15 MHz.

The alum-treated Viking Age archaeological wooden objects from the Oseberg find have undergone extensive chemical deterioration due to the original conservation treatment, based on alum salts (KAl(SO 4 ) 2 ·12H 2 O), done in the early 1900s. Today, the artifacts are highly acidic (pH≤2) and fragile; in some cases wood has almost completely lost its structural integrity. Research on conservation methods for these finds is currently underway. In the present study, organic/inorganic multi-functional ‘hybrid systems’ – using propylene glycol modified TEOS and alkaline nanoparticles (Ca(OH) 2 ) – have been engineered to deacidify and consolidate alum-treated wood in a single step. The advantage of using silicon monomer and nano-materials as a starting point resides in their ease of penetration into the wood structure, where silicon monomers subsequently undergo polymerization. Treated samples were investigated using thermal analysis (DTG), X-Ray Diffraction (XRD), infrared spectroscopy (ATR-FTIR), SEM/EDX and Gas Chromatography Mass Spectroscopy (GC-MS). Results suggest that in addition to consolidating the wood, alkoxysilanes could act as a bridging agent between remaining lignin and calcium hydroxide nanoparticles.

The aim of the present study was to design and synthesize a new class of compounds for the softening of hard water, i.e. for the removal of the divalent cations Ca 2+ and Mg 2+ . To that end, a class of alternating aliphatic polyketones (copolymers of ethylene and propylene with carbon monoxide, PK30) was functionalized with a variety of amines employing the Paal-Knorr reaction, a relatively straightforward reaction-route to synthesize functional polyketones. The amino groups included aliphatic and aromatic structures with a molecular weight ranging from 74.1 to 129.2 g/mol. Elemental analysis was used to establish the degree of functionalization, whereas 1 H-NMR spectroscopy was used to identify the molecular structure of the prepared polymers. Model compounds were used as reference for guiding structure determination and for studying the (relative) reaction kinetics.

Functional polyketones were chemically cross-linked for the softening of hard water, i.e. for the removal of the divalent cations Ca 2+ and Mg 2+ . Elemental analysis, FT-IR spectroscopy, solubility- and swelling-experiments were used to demonstrate the occurrence of the cross-link reaction. Testing the different compounds for their Ca 2+ and Mg 2+ removal capacity assessed the structure-functionality of the polymers. The corresponding water-insoluble resins were then tested for their Ca 2+ and Mg 2+ removal capacity-performance being explained in terms of their chemical structure. Ion adsorption of these polymers is not based on an ion exchange, the prevailing mechanism for most currently existing adsorption resins. Rather, the amino functionalized polymers synthesized here adsorb cations as well as their accompanying anionic counterparts, possibly through a chelating mechanism. The obtained results show that functional polyketones are promising in this context as they are easily tunable with the chemical nature of the N-containing groups determining the affinity of the polymer for Ca 2+ and/or Mg 2+ .

New copper(II) catalytic systems for the mild oxidative C–H functionalization of cycloalkanes and cycloalkenes were developed, which are based on a series of mixed-ligand aminoalcohol-dicarboxylate coordination polymers, namely [Cu 2 (μ-dmea) 2 (μ-nda)(H 2 O) 2 ] n ·2nH 2 O ( 1 ), [Cu 2 (μ-Hmdea) 2 (μ-nda)] n ·2nH 2 O ( 2 ), and [Cu 2 (μ-Hbdea) 2 (μ-nda)] n ·2nH 2 O ( 3 ) that bear slightly different dicopper(II) aminoalcoholate cores, as well as on a structurally distinct dicopper(II) [Cu 2 (H 4 etda) 2 (μ-nda)]·nda·4H 2 O ( 4 ) derivative [ abbreviations : H 2 nda, 2,6-naphthalenedicarboxylic acid; Hdmea, N,N′ -dimethylethanolamine; H 2 mdea, N -methyldiethanolamine; H 2 bdea, N -butyldiethanolamine; H 4 etda, N,N,N′,N′ -tetrakis(2-hydroxyethyl)ethylenediamine]. Compounds 1 – 4 act as homogeneous catalysts in the three types of model catalytic reactions that proceed in aqueous acetonitrile medium under mild conditions (50–60°C): (i) the oxidation of cyclohexane by hydrogen peroxide to cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone, (ii) the oxidation of cycloalkenes (cyclohexene, cyclooctene) by hydrogen peroxide to a mixture of different oxidation products, and (iii) the single-pot hydrocarboxylation of cycloalkanes (cyclopentane, cyclohexane, cycloheptane, cyclooctane) by carbon monoxide, water, and a peroxodisulfate oxidant into the corresponding cycloalkanecarboxylic acids. The catalyst and substrate scope as well as some mechanistic features were investigated; the highest catalytic activity of 1 – 4 was observed in the hydrocarboxylation of cycloalkanes, allowing to achieve up to 50% total product yields (based on substrate).

The structural variability of two series of Mg 2+ - and Zn 2+ - 2-hydroxyphosphonoacetates have been studied in the range of 25–80°C and 95% relative humidity in order to correlate the structure with the proton conductivity properties. In addition to selected previously reported 1D, 2D and 3D materials, a new compound, KZn 6 (OOCCH(OH)PO 3 ) 4 (OH)·5H 2 O (KZn 6 -HPAA-3D), has been prepared and thoroughly characterized. The crystal structure of this solid, solved ab initio from synchrotron X-ray powder diffraction data, consists of a negatively charged 3D framework with K + ions, as compensating counterions. It also contains water molecules filling the cavities in contrast to the potassium-free 3D anhydrous NH 4 Zn(OOCCH(OH)PO 3 ) (NH 4 Zn-HPAA-3D). In the range of temperature studied, the 1D materials exhibit a 1D→2D solid-state transition. At 80°C and 95% RH, the 2D solids show moderate proton conductivities, between 2.1×10 −5 S·cm −1 and 6.7×10 −5 S·cm −1 . The proton conductivity is slightly increased by ammonia adsorption up to 2.6×10 −4 S·cm −1 , although no ammonia intercalation was observed. As synthesized KZn 6 -HPAA-3D exhibits a low proton conductivity, 1.6×10 −6 S·cm −1 , attributed to the basic character of the framework and a low mobility of water molecules. However, this solid transforms to the 2D phase, Zn(OOCCH(OH)PO 3 H)·2H 2 O, upon exposure to dry HCl(g), which enhances the proton conductivity with respect to the as-synthesized 2D material (4.5×10 −4 S·cm −1 ). On the other hand, NH 4 Zn-HPAA-3D exhibited a higher proton conductivity, 1.4×10 −4 S·cm −1 , than the K + analog.

Rod-shaped ZnO crystals were synthesized by chemical precipitation method from aqueous solution. Carboxymethyl inulin (CMI) was used as an additive in ZnO synthesis reaction, and particles with differing sizes and structures were obtained. CMI hindered crystal growth in the length axis of the rods, while growth on the lateral axis was not suppressed. ZnO crystals synthesized with varying CMI concentrations were incorporated into PHBV (3-polyhydroxybutyrate- co -3-hydroxyvalerate) matrix and the effect of the particles on thermal and mechanical properties of the polymer were investigated. Considerably good particle dispersion was obtained in the polymer matrix by melt-extrusion method. ZnO particles did not seem to affect main crystal structure, melting temperature and crystallization temperature of PHBV, whereas they had a retarding effect on crystallization. The addition of ZnO particles into PHBV increased elongation at break and toughness values, along with the decrease in the degree of crystallinity. Tensile strength was also increased without a significant change on the stiffness. Thermal degradation temperatures were observed to slightly decrease with ZnO addition compared to neat PHB; however, degradation peak temperature was still considerably above the melting temperature of the polymer.

In this paper a new method for the removal of gypsum degradation layers from carbonatic matrices in cultural heritage conservation, using aqueous Highly Viscous Polymeric Dispersions (HVPDs) based on partially hydrolyzed poly(vinyl acetate) and borax, embedded with chelators, is presented. Due to their interesting viscoelasticity, these systems guarantee a good adhesion to the treated surface and easiness of removal in one step, minimizing the residues. Thus, they can potentially overcome the “residue question” limit associated to traditional methodologies that use thickened solutions of chelators. Here the rheological properties of HVPDs containing different amounts of selected chelating agents are explored and their efficacy in the extraction of gypsum is verified through cleaning tests onto artificially sulfated travertine tiles. The homogeneous removal of gypsum across the surface was checked non-invasively via Fourier Transform Infrared Spectroscopy (FTIR) 2D Imaging. An analytical protocol for the pre-treatment and the analysis of HVPD samples by means of Ion Cromatography (IC) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) was set up and the approximate amount of calcium sulfate removed was determined.

In this study synthesis and characterization of the new methacrylic derivatives of naphthalene-2,7-diol are presented. This reaction was performed in the three stages. In first stage 2,7-NAF was reacted with dimethyl sulfate in the NaOH solutions at 0°C. Next, the obtained 2,7-NAF.Me was modified by epichlorohydrine leading to epoxide compound (2,7-NAF.Me.EP). Finally, the reaction of opening oxirane rings by methacrylic acid was carried out. The chemical structures of all derivatives were confirmed by 1 H and 13 C NMR. Next, copolymerization reaction with methyl methacrylate (MMA), styrene (St) or divinylbenzene (DVB) was carried out. New monomer (2,7-NAF.MePM) possesses only one double bond and it can be used as a dopant in optical materials technology. The studies of their thermal properties were investigated by means TG/DTG/QMS coupled method. The influence of photoluminescence dopant on thermal stability of the obtained copolymers was also discussed.

In this study, hydroxyapatite (HA) was incorporated in a poly(L-lactic acid) (PLLA) matrix and the thermal properties and crystallization behavior of the derived composites were investigated. The nanocomposites, containing 0–20 wt% HA, were prepared by melt extrusion employing a twin-screw extruder. XRD experiments verified an increase in the intensity of the characteristic diffraction peak of the α -form crystalline phase of PLLA with increasing HA content. By DSC experiments it was observed that the presence of HA increased the crystallinity during cold crystallization, leading to a shift of cold-crystallization temperature to lower values and to an increase in the melting temperature of the PLLA phase. Isothermal crystallization experiments at 100, 110, 115 and 120°C, revealed a maximum in crystallization kinetic around 100°C after the addition of HA compared to 115°C for pure PLLA. The crystallization rate of PLLA matrix in the nanocomposites decreased with increasing crystallization temperature. By using the Avrami and Lauritzen-Hoffman equations the exponent n was calculated in the range 2–3 and a theoretical approach verified that the HA/PLLA systems belong to Regime II of crystallization behavior. The investigated melting behavior of PLLA was attributed to better organized crystalline structure with increasing isothermal crystallization temperatures and might be related with the longer time necessary for the completion of crystallization.

The effect of incorporation of poly(ethylene glycol) (PEG) on thermomechanical and hydrophilicity properties of poly(L-lactic acid) (PLLA) was investigated. PEG/PLLA blends, containing 10, 20, 30 and 40 wt% PEG, were prepared by melt-extrusion in a co-rotating twin-screw extruder. By DSC analysis, it was observed that the T g of PLLA phase in PEG/PLLA blends decreased accompanied by a significant decrease in T cc and increase in their melting enthalpy. Therefore, the addition of PEG enhances the crystallization ability of PLLA phase due to its lubricating effect which increased mobility of PLLA chains. From TGA it was observed that low concentrations of PEG (10 & 20 wt%) increase the T onset of thermal degradation, probably due to improved heat resistance of the crystalline phase. At higher PEG content, the T onset decreases, as the lubricating effect becomes the controlling mechanism for the initiation of degradation process. Decrease in tensile strength and modulus was recorded especially in PLLA blends with PEG content higher than 20 wt%. The elongation at break decreases reaching a maximum at 20 wt% PEG and then dropped again. To investigate the effect of PEG on the wetting ability of PLLA, water contact angle measurements were performed. The results indicate that the introduction of PEG lowers the contact angle values in PEG/PLLA film surfaces, as compared to pure PLLA, suggesting improved hydrophilic properties.

The crystallization of scale forming minerals is an important problem in a number of processes. Calcium sulfate dihydrate (CaSO 4 ·2H 2 O, gypsum) is the most unwelcome deposit in the production of oil and gas, in water cooling systems and in hydrometallurgical processes. Additives have been used in these processes to prevent the formation and deposition of scaling salts. In this study, the effects of additives on the spontaneuos precipitation of CaSO 4 ·2H 2 O were investigated in aqueous solutions at 30°C. Conductive copolymers with different vinylphosphonic acid (VPA) contents were used as additives. The degree of inhibition of cystallization was measured as an increase in induction time and the reduction in crystallization rate. The crystallization reactions were interpreted in terms of the Langmuir adsorption isotherm. The cystals were characterized by scanning electron microscope (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The VPA content of the copolymer and the supersaturation of the solution were found to be effective parameters on CaSO 4 ·2H 2 O crystallization.

In this study, a novel method for the synthesis of hybrid, porous microspheres, including divinylbenzene (DVB), triethoxyvinylsilane (TEVS) and methacrylated lignin (L-Met), is presented. The methacrylic derivatives of kraft lignin were obtained by reaction with methacryloyl chloride according to a new experimental protocol. The course of the modification of lignin was confirmed by attenuated total reflectance (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The emulsion-suspension polymerization method was employed to obtain copolymers of DVD, TEVS and L-Met in spherical forms. The porous structures and morphologies of the obtained lignin-containing functionalized microspheres were investigated by low-temperature nitrogen adsorption data and scanning electron microscopy (SEM). The microspheres are demonstrated to be mesoporous materials with specific surface areas in the range of 430–520 m 2 /g. The effects of the lignin component on the porous structure, shape, swelling and thermal properties of the microspheres were evaluated.

Three well-established one-step approaches, namely, conducting polymer (CP) nanofiber (NF) synthesis by NF seeding, CP nanoclip (NC) synthesis by oxidative template, and microwave (MW) energy-assisted carbonization were systematically combined to prepare carbonaceous nanostructures from CPs, with great potential as the active material for energy storage purposes. Polypyrrole (PPy), as one of the most well-known and commonly studied members of the CP family was prepared in both NF and NC forms, as the sacrificial carbonization precursor, for different property comparison purposes. Due to conducting polymers’ high electron mobility and easily exciting nature under MW irradiation, both PPy NF and NC samples had vigorously interacted with MWs. The as-obtained carbonaceous samples from such interactions exhibited high thermal stabilities, competitive specific capacitance values and long-term stable electrochemical cyclic performances, which are crucial for the active materials used in energy storage applications. Thus, it is believed that, this well-established and well-studied process combination will dominate the large-scale manufacturing of the carbon-based, active energy storage materials from CPs.