Network Structure/Mechanical Property Relationship in Crosslinked Dimethacrylates of Different Chain Lengths

摘要

In this article, the syntheses of three novel dimethacrylates of different chain lengths as well as the mechanical and thermal properties of their copolymers with methyl methacrylate and styrene were studied. The monomers were prepared by the reaction of glycidyl methacrylate with dicarboxylic acid esters obtained from maleic anhydride and ethylene, 1,4-butylene and 1,6-hexylene glycols. The addition reaction of glycidyl methacrylate and the acidic compound was carried out in the presence of basic catalyst, tetraethylammonium bromide. The monomers were UV-copolymerized with methyl methacrylate and styrene in the presence of a photoinitiator which was 2,2-dimethoxy-2-phenyloacetophenone. The prepared polymers were subjected to different studies concerning evaluation of their flexural properties, thermal stability, dynamic mechanical behavior as well as qualitative estimation of the content of unreacted double bonds. The dependence of glass transition temperatures(T_g)as well as degree of inhomogeneity on the crosslinking density has been examined in different copolymer systems. Evidence that the dependence of the T_g on the crosslinking density is not straightforward is presented. Dynamic mechanical measurements have demonstrated that the heterogeneity of the crosslinked polymers depends strongly on the crosslinking density of the system and the nature of methacrylate monomers used. Depending on the monomer size as well as its functionality, the resultant polymer may have features such as crosslinks or residual unsaturations that influence and define the properties of the materials. It is proved that the new dimethacrylates change their functionality in copolymerization with different monovinyl monomers. Also, the degree of unsaturated bonds conversion was found to be growing with the amount of monovinyl in the copolymer.