Synthesis, Characterization, and Polymerization of Ge- and Sn-Substituted [2.2]Paracyclophanes toward Poly(para-xylylene) Films and Their Mechanical Properties

Polymers have had widespread applications in industry over the past few decades. Recently, polymers incorporating heavier group 14 elements (Ge, Sn, and Pb) have gained interest since their oxides are promising for semiconductor applications due to their high dielectric constants and charge mobility. Poly(p-xylylene) (PPX), an important class of polymer, is widely recognized for its transparency, biocompatibility, and the conformality afforded by its polymerization method, chemical vapor deposition (CVD). In this work, PPXs incorporating germanium or tin are prepared via CVD polymerization and the optimal pyrolysis temperatures of their precursors are determined. The ductility, thermal stability, crystallinity, surface topography, and comprehensive and surface chemical compositions are investigated. Sequential changes in the surface oxidation state are confirmed following exposure to air and subsequent oxygen plasma treatment. Comparison of the obtained PPXs with the widely applied chlorinated version PPX-Cl (trade name Parylene C) revealed preserved ductility while exhibiting distinct trends in softness.