Mechanical and Film Properties of Thermally Curable Polysiloxanes

Telechelic glycidyl epoxide siloxanes substituted with either methyl, cyclopentyl, or cyclohexyl groups were cured thermally with corresponding telechelic aliphatic amine. Also, the three glycidyl epoxide functionalized siloxanes were homopolymerized via a photo-initiated cationic mechanism. Both the UV and thermal curing were performed by formulating with reactive diluents. The mechanical properties, viscoelastic behavior, and coatings properties of the thermally cured siloxanes were studied. In addition, the X-ray measurements were performed. The rate of polymerization increased with the increasing size of substituent on the siloxane backbone. The hardness, adhesion, and solvent resistance increased as the bulk of the substituent increased in the siloxane backbone. The release properties for adhesion and readhesion increased with increase in steric bulk of the backbone substituents. Crosslink density reduced and oxygen permeability increased with increase in siloxane substituent size. There was also an increase in the advancing and the receding contact angles with the increase in substituent size. The inverse dependency of substituent size and free volume was observed in the d-spacing of the X-ray data. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 201