Development of Silicone Elastomer-Based Composite Films Containing Ibuprofen and Functional Additives

Silicone elastomers are attractive matrices for transdermal drug delivery systems, but the controlled release of poorly water-soluble drugs from hydrophobic silicone networks remains challenging. Medical-grade silicone elastomers are generally regarded as chemically stable, biologically inert, and highly biocompatible polymer matrices, which supports their use in biomedical and pharmaceutical materials. Here, ibuprofen-loaded silicone/polyol composite films were prepared from hydroxyl-terminated polydimethylsiloxane (PDMS-OH) using glycerol- and 1,2-propylene glycol-derived alkoxysilane cross-linkers and amino-terminated PDMS as a metal-free room-temperature-vulcanising catalyst. The effects of cross-linker composition, glycerol, PEG 200 and selected functional additives on film formation, morphology, apparent ibuprofen release and preliminary Strat-M^® permeation were evaluated. FTIR analysis indicated no covalent reaction between ibuprofen and the silicone network, but suggested hydrogen-bonding interactions with polyol-rich domains, particularly in glycerol-containing systems. Raman mapping supported ibuprofen incorporation within the films, while SEM showed phase-separated microdomains whose morphology depended on the formulation. Apparent release into 0.9% NaCl at 37 °C was formulation-dependent over 72 h. The optimised F-9 film showed approximately 83% cumulative apparent release, whereas the F-10 film containing copper oxide nanoparticles and sea buckthorn oil showed the highest numerical cumulative apparent release, approximately 94%. Kinetic analysis of the apparent release data supported a mainly diffusion-controlled contribution, modulated by hydrophilic microdomains. These results provide preliminary materials-development evidence that silicone/polyol films can be used to tune apparent ibuprofen release and merit further optimisation for local topical or transdermal applications; however, efficient skin permeation and biological performance require dedicated validation.