Preparation and photocuring performance of itaconic acid-derived hyperbranched macromers with internal and terminal C[dbnd]C bonds catalyzed by tetramethylguanidine.

Novel itaconic acid-derived green hyperbranched macromers with polymerizable C=C bonds both in the internal skeleton and periphery were synthesized under mild synthetic conditions. The addition of hyperbranched polymers can make the cured cross-linked network denser and more uniform, and thus, leading to a significant improvement in performance of the coatings. [Display omitted] • Novel itaconic acid-based hyperbranched macromers with C = C bonds both in framework and periphery were designed and synthesized. • Esterification was catalyzed by tetramethylguanidine under mild reaction conditions with simple operations. • The new hyperbranched macromers can effectively promote the photopolymerization performance. • Addition of the hyperbranched macromers leads to a significant improvement in the performance of coatings. A series of hyperbranched polymers derived from biomass itaconic acid was prepared via aliphatic nucleophilic substitution polycondensation reaction under mild conditions by using bis(2-bromoethyl) itaconate and trimeric acid as A 2 and B 3 monomers, respectively, and tetramethylguanidine as catalyst. On this basis, the hyperbranched macromers that contained C = C double bonds in the internal skeleton and the periphery were obtained by further adding A 1 monomer (2-bromoethyl acrylate) directly into the reaction system. The successful synthesis of these macromers were confirmed via proton nuclear magnetic resonance, Fourier transform infrared and gel permeation chromatography. The results of photo-differential scanning calorimetry and rheological experiments showed that these macromers exerted a positive effect on the ultraviolet (UV) curing of commercial resin. The properties of cured splines and coatings, such as mechanical properties, pencil hardness, and thermal stability, were considerably improved with the addition of hyperbranched macromers. They were significantly better than those of linear macromers and macromers that contained polymerizable groups only in the inner framework or their terminal units. The results show that both the inner and terminal C = C double bonds of hyperbranched macromers can participate in UV cross-linking. Thus, such macromers may be used as potential additives for high-performance UV curable coatings. [ABSTRACT FROM AUTHOR]