Porous Polymer by Vapor Deposition Polymerization

摘要

Macro-porous polymers are most commonly prepared by solution- or melt-phase methods including polymerization induced phase separation (PIPS), thermal induced phase separation (TIPS) and other phase inversion techniques. While these techniques have achieved exquisite control of pore size and porosity and are advancing technologies related to membranes for separations, drug delivery, and cellular scaffolding of tissues or implants, it remains challenging to form porous polymer as highly conformal layers or to deposit precise amounts of porous polymer onto targeted areas.;This thesis develops multi-component vapor deposition polymerization (VDP) techniques that force phase separation of as-deposited species, while, at the same time, reactive polymerization is occurring, leading to kinetically trapped macro-scale structure and morphology. It shows that rapid film growth rates can be achieved by initiated chemical vapor deposition (iCVD) of poly(glycidyl methacrylate) from supersaturated monomer vapor. Further, template-free methods were applied to fabricate continuous-phase, porous polymer films by simultaneous phase separation during vapor deposition polymerization. To further understand the process, the degree of interaction between condensed species was systematically varied and experiments were conducted using three different porogens with different cohesive energy densities. Experiments show that the morphology and porosity of the as-deposited polymer thin films depend on deposition rate, crosslinker density, the mass transfer mobilities of phase-separating species, and the interaction energies between species.;Chemical crosslinking around condensed porogen during vapor deposition polymerization offers morphological control of porous polymer within thin, conformal layers. In principle, this strategy could be translated to line-of-sight vapor deposition methods, enabling porous polymer to be grown through a pattern mask, or even directly onto part's surface. The ability to control solid/porous membrane growth and feature size is relevant to the future work including laser fusion targets fabrication, stimuli-responsive porous hydrogel thin films, and multi-stimuli responsive polymers.