CC BY 4.0Jenderny, JonathanJonathanJendernyBoysen, NilsNilsBoysenRubner, JensJensRubnerZysk, FrederikFrederikZyskPreischel, FlorianFlorianPreischelArcos, Teresa de losTeresa de losArcosDamerla, Varun RajVarun RajDamerlaKostka, AleksanderAleksanderKostkaFranke, JonasJonasFrankeDahlmann, RainerRainerDahlmannKühne, Thomas D.Thomas D.KühneWessling, MatthiasMatthiasWesslingAwakowicz, PeterPeterAwakowiczDevi, AnjanaAnjanaDevi2024-09-242024-09-242024https://publica.fraunhofer.de/handle/publica/475544https://doi.org/10.24406/publica-369110.1002/admi.20240017110.24406/publica-3691Vapor phase infiltration (VPI) has emerged as a promising tool for fabrication of novel hybrid materials. In the field of polymeric gas separation membranes, a beneficial impact on stability and membrane performance is known for several polymers with differing functional groups. This study for the first time investigates VPI of trimethylaluminum (TMA) into poly(1-trimethylsilyl-1-propyne) (PTMSP), featuring a carbon–carbon double bond as functional group. Saturation of the precursor inside the polymer is already attained after 60 s infiltration time leading to significant densification of the material. Depth profiling proves accumulation of aluminum in the polymer itself, but a significantly increased accumulation is visible in the gradient layer between polymer and SiO2 substrate. A reaction pathway is proposed and supplemented by density-functional theory (DFT) calculations. Infrared spectra derived from both experiments and simulation support the presented reaction pathway. In terms of permeance, a favorable impact on selectivity is observed for infiltration times up to 1 s. Longer infiltration times yield greatly reduced permeance values close or even below the detection limit of the measurement device. The present results of this study set a strong basis for the application of VPI on polymers for gas-barrier and membrane applications in the future.engas separationmembranePTMSPTMAvapor phase infiltrationjournal article