A novel enantiopure phenyl isocyanide (1) carrying tert-butyloxycarboryl (Boc) protected L-prolinol ester was designed and synthesized. Living polymerization of 1 using a alkyne−Pd(II) catalyst afforded helical poly-1 m s in high yields with controlled molecular weights (M n s) and narrow molecular weight distributions (M w /M n s). Removing the protecting Boc groups on the L-prolinol ester pendants lead to the formation of helical poly-2 m , which showed high optical activity owing to the preferred left-handed helix of polyisocyanide main chain. The poly-2 m s showed excellent catalytic ability on asymmetric Michael addition reaction. Both the enantiomeric excess (ee) and diastereomeric ratio (dr) values of the product were linearly correlated to the M n and optical activity of poly-2 m . Increasing the M n of poly-2 m s will amplify the stereoselectivity of the asymmetric Michael addition reaction until the M n reached to 44.9 kDa, revealing the polymerization amplified stereoselectivity (PASS) behavior of the asymmetric reaction. Under optimized the reaction condition, the ee and dr values of the Michael addition reaction product can be up to 99% and >99/1, respectively. Poly-2 200 can be easily recovered and reused in the Michael addition reaction for at least 5 cycles without loss of its activity and stereoselectivity significantly. The poly-2 200 can also be used to catalyze the asymmetric aldol reaction. The ee and dr values of the model aldol reaction were respectively up to 99% and >99/1. Moreover, the poly-2 200 can be facilely recovered and alternatively catalyzed Michael addition reaction and aldol reactions for at least six cycles with maintained selectivity and activity.
In this article, a series of carboxylated acrylate copolymer latices were prepared based on the semicontinuous emulsion polymerization via the pure monomer dropwise manner with three different kinds of carboxylic monomers in presence of reactive emulsifier. The effects of the carboxylic monomers [acrylic acid, methacrylic acid, and monobutyl itaconate (MBI)] on the conversion and the properties of acrylate latices and films have been investigated. The carboxylic groups (ACOOH) distribution of these three kinds of latices were investigated as well. The results show that the concentration of surface ACOOH (C S ) and embedded ACOOH (C b ) both increase with the increase of the amount of carboxylic monomers. It shows that MBI, the most hydrophobic of the three carboxylic monomers used, tends to be concentrated inside the particle core, and the latex particles have a narrow size distribution. The results of common stability test have demonstrated that the stability of the latex is satisfactory. Moreover, the water absorption and the acid and alkaline resistance of the latex depend on the kind of carboxylic monomer.
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