The Role of Entanglements in the Swelling of Poly(dimethylsiloxane) Networks
TOTAL ARMY PERSONNEL COMMAND ALEXANDRIA VA
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The swelling of model and imperfect polydimethylsiloxane PDMS networks in solvents and polymer chains were studied to see how the role of entanglements affects the predictions of the Flory-Rehner swelling model. The model networks were prepared by end-linking difunctional PDMS B2 with a given amount of tetrafunctional crosslinker A4 to obtain networks with a minimum amount of elastically ineffective chains. The imperfect networks were prepared by end-linking mixtures of monofunctional PDMS B1, B2, and A4 to obtain networks containing pendant chains and branched structures. The equilibrium elastic moduli, Ge, of the networks were determined from dynamic mechanical experiments and were found to be greater than the values predicted from the affine and phantom network theories when using a branching model of nonlinear polymerization Macosko-Miller model to characterize the networks.
- Physical Chemistry
- Polymer Chemistry