Maleimides, photoinitiator-free

Photoinitiator Free Polymerization of Maleimides and Vinyl Ethers... 

In order for maleimide/vinyl ether photoinitiator free photopolymerization to be useful, it is important that the cured films have good thermal/UV stability. Since there are no small molecule photoinitiators added to the uncured mixture initially, there is no residual small molecule photo initiator present in the final crosslinked film. This accounts for the enhanced UV stability we have observed for cured maleimide/vinyl ether films. In addition, TGA thermograms of photocured films of the MPBM/CHVE mixture (Figure 8) exhibit excellent thermal stability, with decomposition occurring at higher temperatures than for a simple UV cured HDDA film with 3 weight percent DMAP photoinitiator. (Such thermal stability would be... 

Decker C, Morel F, Jdnsson S, et al. Light-induced polymerization of photoinitiator-free vinyl-ether-maleimide systems. Macromol ChemPhys. 1999 200 1005-1013. 

Difunctional vinvl ether/difunctional N-maleimide. Up until this point, our results have centered on the reactivity of monofunctional maleimide divinyl ether mixtures. From Kloosterboer s26 work for acrylate polymerization, it is known that the rate of polymerization of a free-radical process is increased dramatically as the functionality of the acrylate is increased. In order to enhance the polymerization rates of maleimide divinyl ether systems, it was decided to synthesize difimctional maleimides for copolymerization with difunctional vinyl ethers. The results in Table V indicate that the photoinitiated TTDBM [bismaleimide made from maleic anhydride and 4,7,10-... 

Photocondensation Polymerization.—This term is used in the sense that the polymerization requires the absorption of a photon for every propagation step, as distinct from the photoinitiation of the free-radical chain addition polymerization discussed above. The photodimerization reaction (14) of maleimides in... 

There are definite attractions for monomers that can be used without the aid of initiators. Such monomers are maleimides. The monomers based on vinyl acrylate are also capable of self initiation. The vinyl ester itself, however, is too volatile for practical use and its initiation of polymerization is slower than obtained with the traditional photoinitiators. When the acrylate group is replaced by crotonate, cinnamate, fumarate, or maleate chromophores, these monomers copolymerize readily with thiol and vinyl ether monomers and initiate free-radical polymerization upon direct excitation in the absence of any added photoinitiator. 

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