Stereochemical Control of Water Transport Properties in Thiol-yne Polymers

Barrier polymers underpin almost every commercial sector, yet the needs of several emerging areas remain unmet by commercially-available materials, including temporary orthopedic implants, transient health monitors, neural implants, and other long-term implants. The ability to tune polymer composition independently of polymer structure positions thiol-yne click chemistry as a promising platform to serve these emerging technologies. This work describes the differences in the hierarchical structure of stoichiometrically identical materials which differ only in the proportion of the cis versus trans backbone alkene stereochemistry. Varying the isomer content in this way directs different temperature and rate dependent crystallization behavior, which affords control over micron-scale structure. This investigation focuses on how these stereochemical features affect the water vapor permeation process by several methods and develops an understanding of how this unique structural regularity improves barrier performance relative to a commercially available water barrier polymer, poly(ethylene terephthalate).