Crystallization of polydimethylsiloxane end-linked networks

Summary

End-linked polydimethylsiloxane networks were synthesized, and used to quantify the reduction due to crosslinking of both the extent and thermodynamic stability of the crystalline phase. Networks of varying crosslink density were isothermally crystallized at various temperatures. The consequent melting points were found to be a linear function of the crystallization temperature, enabling equilibrium melting temperatures to be determined by extrapolation. From the dependence of the equilibrium melting point on crosslink density, it was determined that a network junction precludes roughly 8 adjoining chain units from incorporating into the crystal phase. This result is consistent with the measured degree of crystallinity suppression in the networks.