Polymer Science and Composite Materials

Polymer chemistry is a sub-discipline of chemistry that focuses on the structures of chemicals, chemical synthesis, and chemical and physical properties of polymers and macromolecules. The principles and methods used within polymer chemistry are also applicable through a wide range of other chemistry sub-disciplines like organic chemistry, analytical chemistry, and physical chemistry. Many materials have polymeric structures, from fully inorganic metals and ceramics to DNA and other biological molecules. However, polymer chemistry is typically related to synthetic and organic compositions. Polymer chemistry can also be included in the broader fields of polymer science or even nanotechnology, both of which can be described as encompassing polymer physics and polymer engineering.

Biological polypeptides are complex copolymers that derive their phenomenal properties from precisely controlled sequences and compositions of the constituent amino acid monomers, which in turn lead to precisely controlled chain shapes and self-assembled structures. While these materials can be synthetically produced, they are made in notoriously low yield and small quantities.

Biotechnology has been applied as a valuable tool to produce useful bio-based products from non-petrochemical renewable resources. Biologically-produced polymers present advantages related with the biodegradability, performance, cheapness of substrate and defined structural variability. Beyond that, enzymes, the most proficient catalysts, continue to offer the most competitive processes compared with the chemical ones. Advances in protein engineering technology and the environmental and economic requirements contribute for the continuous search of acceptable biotechnological solutions for these areas, including, polymer and textile, medical, pharmaceutical, among others.

Smart polymers, stimuli-responsive polymers or functional polymers are high-performance polymers that change according to the environment they are in. Such materials can be sensitive to a number of factors, such as temperature, humidity, pH, chemical compounds, the wavelength or intensity of light or an electrical or magnetic field and can respond in various ways, like altering color or transparency, becoming conductive or permeable to water or changing shape (shape memory polymers). Usually, slight changes in the environment are sufficient to induce large changes in the polymer's properties.

The main two groups of biopolymers are nonbiodegradable and biodegradable, according to degradation. Other classifications according to the origins of biopolymers are bio-based and fossil fuel-based. The main sources of bio-based polymers are animals, plants, and microorganisms. Biocomposites offer a significant non-food market for agro residue-derived resins and fibres towards development of a new generation of biocomposite and biopolymer-based materials with possible applications in other areas.

Polymer processing technologies are the processes in which monomer (bio-based raw materials or low molecular weight substances) are converted into a finished product via chemical reaction, shaping, compounding, and so on. Rheology is a key characterization technique for developing materials with the desired physical properties and for controlling the manufacturing process in order to ensure product quality. Rheology is very sensitive to small changes of the material's polymer structure – thus ideal for characterization of polymers.

The use of additive manufacturing (AM) has moved well beyond prototyping and has been established as a highly versatile manufacturing method with demonstrated potential to completely transform traditional manufacturing in the future. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM.

Sustainable polymers from renewable resources can be obtained through chemical modification of natural polymers, such as starch, cellulose, or chitin. Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites.

Polymer synthesis, also called polymerization, is the process by which monomers (small molecules) are covalently bonded to form a (usually long) polymer chain or network. Polymer characterization techniques are categorized as chromatographic, thermal, spectroscopic, microscopic, rheometric, or mechanical.

Biomedical polymers are essentially a biomaterial that is used and adapted for a medical application. Biomedical polymer can have a beginning functional, such as being used for a heart valve and more interactive purpose such as hydroxyl apatite coated in implant. Natural biodegradable polymers are called biopolymers. Polysaccharides, as starch and cellulose, represent the most characteristic family of these natural polymers. Other natural polymers as proteins can be used to produce biodegradable materials. These are the two main renewable sources of biopolymers.

Polymer science and engineering is revolutionary since polymeric materials can be designed to meet the ever more demanding needs of advanced technology. In the environmental field, there is a place for creating new polymeric materials, modifying existing polymers or even discovering green and novel applications of conventional polymers. Thus, polymer scientists and engineers have the capability of helping to make our planet a better place to live.

Solid waste treatment is a significant problem nowadays. Millions of solid waste is produced worldwide per year. They are often trashed to landfills but this is both an ecologically and economically unacceptable way. A sustainable alternative is the use of wastes as secondary materials for the manufacture of different types of products. Special emphasis is placed on the recycling of polymeric waste and on the way of their management respecting the principle of waste hierarchy: minimization/prevention, collection, separation, identification, recovery by recycling, biological recovery, energy recovery by incineration and storage in ecological landfills.

Polymer materials, together with their composites, are emerging as an important role in the field of energy applications. They hold the potential to provide versatile solutions for the challenges encountered in the fields of both energy storage and energy harvesting. Particularly, the booming of flexible electronics calls for a consistent and reliable power supply. Thus, various energy storage and harvesting systems with their respective characteristics serving as an indispensable component for these electronics are highly needed. Compared to inorganic materials, polymers and polymer-based composites exhibit the merits of easy-processability, intrinsic flexibility, low cost and structural tunability, revealing high potential in flexible electronics. These features also allow for easier assembly of highly-integrated multi-functional energy devices, thereby can promote the development of new energy techniques for practical applications.

High-performance composites (HPC), composed of reinforcement (fibers, particles, fillers, etc.) and matrix (polymers, metals, ceramics, etc.), are used widely as advanced materials. Oriented continuous fibers as reinforcements primarily determine strength and modulus.

Polymer nanocomposites (PNC) consist of a polymer or copolymer having nanoparticles or nanofillers dispersed in the polymer matrix. These may be of different shape (e.g., platelets, fibers, spheroids), but at least one dimension must be in the range of 1–50 nm. These PNC's belong to the category of multi-phase systems (MPS, viz. blends, composites, and foams) that consume nearly 95% of plastics production. These systems require controlled mixing/compounding, stabilization of the achieved dispersion, orientation of the dispersed phase, and the compounding strategies for all MPS, including PNC, are similar. Alternatively, polymer can be infiltrated into 1D, 2D, 3D preform creating high content polymer nanocomposites.

Polymers with the ability to kill or inhibit the growth of microorganisms such as bacteria, fungi, or viruses are classified as antimicrobial agents. This class of polymers consists of natural polymers with inherent antimicrobial activity and polymers modified to exhibit antimicrobial activity.

The annual amount of trash produced worldwide by industrial, agricultural, and urban activities increases steadily and contributes to catastrophic environmental contamination, which is fueled by fast urbanisation and rising populations. Special management is necessary due to the growing problems caused by waste generation. Using solid waste from industrial, urban/municipal, and agricultural/forest activities as reinforcements in polymer composites is one sustainable waste management strategy.

Molecular modeling and simulations are invaluable tools for the polymer science and engineering community. These computational approaches enable predictions and provide explanations of experimentally observed macromolecular structure, dynamics, thermodynamics, and microscopic and macroscopic material properties. With recent advances in computing power, polymer simulations can synergistically inform, guide, and complement in vitro macromolecular materials design and discovery efforts.

All the registered participants will be given 50% discount on APC to publish their full-length article in the special issue of the Scopus index journal. (*Subjected to acceptance through a peer-review process).