Mechanical properties of acrylate networks formed by visible laser‐induced polymerization. I. Dependence on photopolymerization parameters

Abstract The mechanical properties of network molecular systems, prepared through visible (Ar+) laser‐induced polymerization of multifunctional acrylates, were studied as a function of some of the photopolymerization parameters. The properties investigated were the Young's modulus of elasticity and the stress‐at‐break, both derived from the stress versus strain test of dogbone‐shaped photopolymerized samples. The parameters studied included the dye and co‐initiator concentrations, and the laser power. We also compared the mechanical properties of samples made using different types of fluorone dyes and using two different amines as co‐initiator. Better polymers are formed by the dyes with low fluorescence quantum yield. The three photopolymerization parameters modify the mechanical properties in a very similar way: they initially tend to increase both the Young's modulus and the stress‐at‐break but have a deleterious effect on the material strength if used in excess. N‐phenylglycine, NPG, was shown to form stronger polymers (higher Young's modulus) than if N,N‐dimethyl‐2,6‐diisopropylaniline, DIDMA, was used as co‐initiator. We discuss the possible molecular mechanisms for such observations. © 1994 John Wiley & Sons, Inc.