Spectroscopic properties of polymer composites

Polymers and polymer composites have been present in human life for a long time. Every day, we use many objects made of polymers, e. g. disposable tableware made of polyethylene (PE) or polypropylene (PP) are with us during the family picnics and holiday trips. We drink water from plastic bottles, eat using plastic cutlery, and so on. On the other hand, we see polymers and polymer composites as essential parts in equipment at homes, public buildings, cars, aircrafts, and different machines. Moreover, the role of these materials has become significant for our organisms. Nowadays, polymeric biomaterials play important roles in medicine for example as resorbable substrates for tissue regeneration control, construction implants of tailored mechanical properties and controlled resorption time, construction of prostheses, dental materials, artificial coronary vessels, a drug carrier, biostable joining elements, surgical sutures, and dressing materials. The polymers most often used in medical applications are polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polystyrene (PS), PE, polytetrafluoroethylene (PTFE), PP, polymethyl methacrylate (PMMA), polycarbonate (PC), and many others. Moreover, biomaterials are generally made of polymer composites. Additionally, they can include metals and metal alloys (e. g. Fe, Co, Cr-Ti, and amalgams), ceramic materials (e. g. bioglass and hydroxyapatite) or possibly cells and human tissues. Generally, it is worth noting that organic–inorganic hybrid materials such as polymer-ceramics and polymercarbon very often are applied as biomaterials or materials used in electronics and optoelectronics. According to literature, essential and very often used components of polymer composites are different allotropic forms of carbon, e. g. graphene, graphene nanoribbons (GNRs), and singleor multiwalled carbon nanotubes (MWCNTs). Thus, owing to interesting electronic and mechanical properties of GNRs, they have become promising materials for preparation of conductive composites for applications as transparent electrodes, heat circuits, and supercapacitors [1]. On the other hand, chemical modification of graphene by photopolymerization with styrene results in self-organized intercalative growth and delamination of graphene with few layers. Such composites are extremely promising for a wide range of mechanical, thermal, and electrical applications [2]. An interesting report was that on electron field emission (FE) from reduced graphene oxide (rGO):poly(3hexylthiophene) (P3HT) composite layers [3]. Reduced graphene oxide can also have potential applications in vacuum microelectronic devices, such as microwave power amplifiers and FE-based electronic devices such as flat panel FE displays (FEDs) [4–6]. Graphene fibers provide new ways to study interfacial interactions between the polymer and graphene for producing high-performance graphene-enhanced polymer nanocomposites. As an example, transcrystallization of isotactic polypropylene (iPP) surrounding the graphene fibers can be shown. The results indicate that fabrication of effective graphene-enhanced polymer nanocomposites can be used for various emerging applications [7]. Graphene-based polymer composites are also developed for potential use in biomedical applications. Soft biomedical polymers can be strengthened by incorporating graphene in the polymer matrix for use in hard tissue applications such as orthopedic repair and regeneration in the form of fracture fixation devices, tissue scaffolds, etc. [8]. Another form of carbon used as fillers in polymer composites or hybrid materials is carbon nanotube (CNT), generally due to its extremely high Young’s modulus, stiffness, and flexibility. Considering first single-walled carbon nanotubes (SWCNTs) as a candidate for application in producing composite materials, it should be noted that successful application requires well-dispersed nanotubes with good adhesion to the host matrix, which is not easy to realize. Moreover, weak nanotube–polymer interactions result in poor interfacial adhesion, which can cause nanotube aggregation within the matrix. A novel approach to in situ composite synthesis, by attachment of PS chains to full-length pristine SWCNTs without disrupting the original structure, has been proposed [9]. For some applications, solid-phase deposition of CNTs at the site of action is realized, but for other ones