Definition of materials chemistry (IUPAC Recommendations 2024)

Note 1:

The aspects of design, synthesis, and function (useful or potentially useful properties) are all needed for the topical item of material research/development/production to be part of materials chemistry.

Note 2:

The keywords “useful” and “properties” emphasize functionality as a major driving force of the practitioners of materials chemistry.

Note 3:

For a series of further details on both the structure-property relation and functionality by design, read below in this recommendation and in the source. ¹

A selection of examples and the rationale underpinning the cross-disciplinary nature of materials chemistry are given below. Much of materials chemistry is motivated by discovering and developing materials for desired applications. Whilst this is an essential motivating factor, the need to develop the structure–property relation is crucial for any category of chemicals to be a material useful for the well-being of humankind. Key tools of practitioners of materials chemistry are chemistry-based approaches in general. Work that considers only the synthesis and characterization of new chemical substances is simply chemical synthesis, not materials chemistry. Synthesis and characterization of new chemical substances with additional inherent focus on its properties useful to humankind is considered materials chemistry.

There are several successful examples of educational resources for solid state and materials chemistry, such as online resources in the IUPAC webpage of Materials Chemistry EDU, ⁴ or textbooks ^{7 , 8 , 9} that provide a common language for teaching in the area. The introductory chapters of Woodward et al. ⁷ cover topics such as crystal structures, defects, diffusion in solids, chemical bonding, and electronic band structure. The textbook further navigates the reader toward the examples and to the understanding why and how the useful properties of materials can ultimately be traced back to structure and dynamics at the atomic level and also controlled from this level. Also new editions of textbooks are valuable educational tools ^{8 , 9} that can concisely document how the central role of chemistry in materials science stems from the ability to design and synthesize new materials with properties previously never observed. For example, individual chapters of Fahlman’s textbook ⁹ conclude with sections describing important material applications as well as addressing thought-provoking questions to readers.

The report of P. Day et al. ¹ states that “… synthesizing a new chemical substance in nano- or macroscopic form is not materials chemistry but just chemical synthesis … to be considered materials chemistry there needs to be an element of application, function, or design ….” In general, the features of application, function, and design serve to discern a “material” from a “chemical.” The progress of knowledge about nanomaterials and potentially useful properties and application of these is justified also by further detail: nanomaterials and their properties represent specific fields in which, besides the design, synthesis is already implicit in the topic. The main purpose of their synthesis is to control both the surface area of nanomaterials and the size of nanoparticles below 100 nm or even below 10 nm. Such small nanoparticles have very different physicochemical and biophysical properties and therefore also different application/function and potential when compared to the bulk material.

This and the next paragraphs quote several focused examples and topics within the field of materials chemistry. Structural details provide a series of structure–property relationships topical in materials chemistry. ^{1 , 7 , 8 , 9} An example with long history, referred also in ref. ¹ , provides the construction industry with solutions based on recent research in this area. The compound Ca₂SiO₄, especially its polymorphs affecting the formation of concrete from cement, illustrates the role of structural modifications ¹⁰ on properties. The γ-polymorph reacts with water negligibly, yet its reaction with CO₂ dissolved in water may increase the strength of concrete. ¹¹ The β-polymorph of Ca₂SiO₄ in Portland cement reacts quickly with water, the added value of materials chemistry in novel cement-based materials is the knowledge on the cross-linking of selected atoms of cement and polymer, ¹² while strength of the material ^{10 , 11 , 12} is a challenge. This example illustrates how the construction industry, and much of its novelty, rest on the detailed packing arrangement of the atoms in components of cement and its partner compound.

Topical up-to-date cutting-edge research and development on the structure–property relationships in the field of materials chemistry include research in polymer materials. ¹ By focusing on the structure and elemental composition with an eye toward properties, polymers are viewed as molecular materials where useful collective properties result from the interactions between individual component molecules. Furthermore, organic groups on polymers can be modified to control physical and chemical properties. Polymer materials, including the design and synthesis of derivatives of biopolymers, are utilized in a variety of technological applications. ¹³ Applications include, but are not limited to, solid-state batteries, composite materials (including micro-structured metamaterial designs), isotropic transparent polymeric materials, organic light-emitting diodes, nonlinear optics, and also biomedical applications or water treatment technologies.

The fast-growing field of biomaterials is an area of challenge in materials chemistry. Entirely synthetic or derivatives of natural, with or without an organic component, biomaterials interact with biological systems and are mostly used in tissue engineering and medicine to replace, regenerate, repair, or augment any body part in terms of structure and/or function. Sometimes these may also satisfy an aesthetic demand. While biomaterials do not fulfill the function of a drug, the issue and potential impact of materials chemistry in this field (besides abovementioned functions) is also in the design and development of biomaterials in drug delivery systems. Thus, typical and common biomaterials, and also novel synthetic materials examples, exert useful or potentially useful bio-relevant properties and functions. ^{14 , 15 , 16 , 17 , 18 , 19} The examples comprise (i) metals and alloys, such as Ti-, Mg-, or Ta-based alloys for bone fixation and joint replacements; (ii) ceramics, such as alumina, zirconia, calcium phosphates, hydroxyapatite for bone cement, and dental implants attached to the tooth; (iii) polymers, such as polyethylene, polymethylmethacrylate, silicones, hydrogels for contact lenses, implants, and artificial ligaments; and (iv) oxides and nonmetallic elements, such as SiO₂, iron oxides, carbon for abrasive components of skin care products, and tattoo colors. Biomaterials should not be confused with biominerals – naturally occurring minerals integrated in the body of organisms. ¹⁸ The important group of biomaterials contains also naturally occurring biopolymers, ^{14 , 15 , 19 , 20} such as cellulose, silk, chitosan, collagen, hyaluronan, elastin, and alginate. However, due to the fact of natural occurrence (and thus no design nor synthesis needed), these should not be considered the topic of materials chemistry.

Another large area of research is perovskites and perovskite-based materials which has grown because of the prominent impact of chemistry-based approaches on materials properties and functionality. The current pace of research and innovation ²¹ spans from tailoring the composition to controlling functionality, as for example in the photovoltaics sector. Perovskites are generally described with the chemical formula ABX₃ (typically A and B are metal cations and X is an anion). The structure is robust so that perovskite materials can host a large variety of constituents to affect properties and potential of application. Perhaps the most prominent applications of perovskite materials are solar cells and photovoltaics in which the selection of perovskite material can effectively determine the cell efficiency. ²¹

A recent example is based in sonochemistry, which is the use of (ultra)sonic waves to trigger chemical reactions. Sonochemistry exerts huge potential to manufacture innovative functional (nano)materials and coatings with magnetic, fluorescent, and antimicrobial properties. ^{22 , 23 , 24 , 25} The sonogalvanic method has been reported to effectively modify the surface of porous silicon by palladium nanoparticles. ²⁶ As an emerging technology, sonochemical coatings may be in future a route toward safer, more durable materials with value-added properties. For these reasons, possibilities are explored to scale up this method to an industrial setting that will enable continuous production of coated materials. ²⁵