Preparation of organic, inorganic hybrid polymer films and fibres by solvent crazing

This thesis focuses on the preparation of functional synthetic polymer fibers and films using the process called solvent crazing. Solvent crazing is a very complex phenomenon, which is realized by polymer drawing in the presence of liquid environment. Four principle stages of solvent crazing i.e. craze nucleation, craze propagation, craze thickening, and collapse of the formed porous structure (controlled by fibril flexibility). The final stage involves effective fibril coagulation which is accompanied by syneresis i.e. transport of certain fraction of liquid from the craze porous structure. The advantages of the proposed approach of solvent crazing are that, as this method does not require any thermodynamic compatibility between components, compounds can be incorporated in the polymer bulk in the form of additives dissolved in the solvent/medium that wets the polymer surface. One can use quite different polymers and additives in the process for the preparation of wide range of polymer blends. Process is limited with the use of low or partially oriented polymer material and the liquid medium (solvents) in which the polymer material is stretched. As solvent crazing is not limited to a particular polymer, here, PET was chosen as a polymer material to study the process since, it is frequently used alone or in combination with natural material for various applications. Furthermore, depending on the additives introduced in the polymer bulk, the applications of the functionalized polymers were discussed in the upcoming chapters. The process is used to prepare:- PET fibers imparting white light with the combination of rhodamine B (red fluorescence), auramine (green fluorescence), and blankophor CLE (blue fluorescence) dyes respectively.- Antibacterial active PET fibers by incorporating zinc ions for the use in medical textiles applications such as dressings, band-aids, masks and other single-use items. - Anisotropically conductive film by subsequent precipitation of metallic silver nanoparticles in the crazes. Although the crazing process so far does not give rise to highly regular patterns, the material might be considered as an alternative to commercial ribbon cables in some special cases, and could be used for electronic interconnects, electrostatic protection and electromagnetic interference shielding, wire-grid polarizers, and other passive microwave components