Effect of hydrophilic inclusions on PDMS crosslinking reaction and its interrelation with mechanical and water sorption properties of cured films

Polydimethylsiloxane (PDMS) elastomeric films containing various amounts of polyethylene glycol (PEG) of molecular weight 3000 g/mol were studied. The work focuses on the effect of the presence of PEG on the vulcanization of PDMS and on the properties of the cured PDMS–PEG films. Information on the interference of PEG with the PDMS crosslinking reaction was derived from (i) non-isothermal DSC studies of the crosslinking reaction and (ii) from the tensile properties of the cured films, evaluated on the basis of the Maxwell model for composite materials. Water sorption studies show that the sorption capacity of the incorporated PEG phase increases with increasing PEG content of the PDMS–PEG films. This effect was correlated with the corresponding decrease of the Young’s modulus, in the light of a theoretical approach on the osmotic effects of hydrophilic inclusions in hydrophobic polymers.