Physical and Chemical Modifications of Thiol-Ene Networks to Control Activation Energy of Enthalpy Relaxation

Document Type

Article

Publication Date

12-10-2009

Department

Polymers and High Performance Materials

Abstract

Gold nanoparticles and multi-functional acrylate (TMPTA) were incorporated into a photopolymerized thiol-ene (TMPMP-APE) network as a physical and chemical approach to intentionally control sub-T(g) aging. The degree of the restriction effect was evaluated by differential cooling rate measurements allowing the quantification of the apparent activation energy for enthalpy relaxation (Delta h*) upon sub-T(g) aging. Incorporation of gold nanoparticles (0.01 to 1 wt%) into the TMPMP-APE network increased T(g) and decreased Delta C(p) at T(g) due to molecular mobility restrictions. The extent of enthalpy relaxation and apparent activation energy for enthalpy relaxation (Delta h*) clearly indicated the significant restrictive effect of the gold nanoparticles on the molecular mobility in the thiol-ene network. A TMPMP-APE-TMPTA ternary system was investigated in order to correlate Delta h* and network uniformity as a chemical approach. TMPTA, being capable of homopolymerization as well as TMPMP-TMPTA copolymerization, was incorporated into a TMPMP-APE network Structure, thereby decreasing the network uniformity and significantly affecting the sub-T(g) aging. The extent of enthalpy relaxation decreased and the distribution was drastically broadened as a function of TMPTA content due to molecular mobility restrictions, which were also quantified by measuring values for the apparent enthalpy relaxation activation energy (Delta h). (C) 2009 Elsevier Ltd. All rights reserved.

Publication Title

Polymer

Volume

50

Issue

26

First Page

6281

Last Page

6286

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