Solution and Solid C13 NMR Studies of Polyolacrylate Networks

摘要

We introduce the use of several C13 NMR techniques to address the problem of thestructures of photopolymerized polyolacrylates. We have used these techniques to study both the liquid and solid states of acrylic monomers and oligomers and the network structure formed upon their photopolymerization. High resolution NMR has allowed us to consider the molecular structure of the acrylic groups belonging to each of a series of polyolacrylate monomers. In photopolymerization experiments, by measuring the relative intensity of specific peaks in the carbon spectra as a function of time of irradiation and laser power, it is possible to determine the relative reactivity of monomers/oligomers used in the early stages of polymerization. By monitoring the variation of the proton T1p relaxation time, changes in the cross-link density and in the mobility of the polymeric chains, can be followed throughout the photopolymerization process. The degree of crosslinking is correlated to the relaxation times and increases with an increasing power of the irradiating laser even under conditions where the degree of conversion as measured by quantitative infrared absorption of the 810/cm band of the acrylate is unchanged. jg p. 2.