13 - Polymer nanocomposites for biomedical applications

Abstract

Polymer nanocomposites are multiphase solid materials formed by one or more polymer matrices and nanometric reinforcing phases having 1, 2, or 3 dimensional structures within the size of nanomaterial. Normally polymer composite materials (PNCs) involve polymer matrices because they are easy to process, shape, have reasonable mechanical properties, and allow for controlled surface and interfacial chemistry. Small size of nanoparticles is of immense importance due to which they impart high surface-to-volume ratio and provide high-energy surfaces. The desirable results of embedding nanoparticles into a polymer matrix extensively enhance the bonding between the polymer matrix and filler, resulting from the nanoparticles’ high interfacial energy. Classical composite theory predicts that improved bonding between the polymer matrix and the reinforcing phase leads to improved mechanical properties. Recently, the polymeric material modified with nanosized reinforcement material has attracted scientific and industrial societies for their outstanding applications. The nanosized material being used are layered silicates, graphite nanosheets, carbon nanotubes (CNTs), metal oxide, and titanate. These materials enhance the properties of polymer material in an engineered way, and they are needed in a very low concentration. The nanostructured reinforcement materials are used generally for the enhancement of properties like increased tensile strength, modulus, hardness and fracture toughness, decreased gas permeability, lower gas flammability, improved thermal stability, and specific heat resistivity. Besides the other properties of CNTs, their excellent mechanical strength and thermal and electrical conductivity make them ideal reinforcing fillers for several polymer matrices. The PNCs obtained by modification of polymer with CNTs possesses exceptionally high electrical and thermal conductivities while the polymer matrix properties (including elasticity, strength, and modulus) remain intact.