Functionalization of poly(methyl acrylate) with formate esters and polyester through ester-ester exchange reaction

Alkoxide-catalyzed ester-ester exchange reaction of poly(methyl acrylate) (PMA) with alkyl formate or polyester was investigated. In the transesterification of PMA with benzyl formate (1a), we found that the reaction of PMA with 2 equivalents of 1a in the presence of 5 mol% of potassium tert-butoxide ((BuOK)-Bu-t) in diglyme under reduced pressure (90 Torr) at 120 degrees C resulted in quantitative conversion of the methyl ester moiety of PMA to the benzyl ester. Under similar conditions, hexyloxy, 2-methylpentyloxy, and 2-pyrenemethoyl groups were introduced into PMA with high efficiency by means of the transesterification of PMA with the corresponding formate. Furthermore, the transesterification of PMA with 23 mol% of poly(dodecamethylene isophthalate) (PEs) proceeded in the presence of 7 mol% of (BuOK)-Bu-t in diglyme at 120 degrees C for 1 day to afford PMA grafted with PEs (composition molar ratio PEs/PMA = 19/81). As another approach to the graft copolymer, we attempted the polycondensation of 1,12-dodecanediol formate (2) and methyl isophthalate (3) in the presence of 20 mol% of PMA and 5 mol% of (BuOK)-Bu-t in toluene under reduced pressure at 60 degrees C, but this reaction afforded a gel. However, the polycondensation of 2 and 3 followed by the reaction with PMA at 60 degrees C gave a soluble graft copolymer with PEs/PMA = 87/13 in good yield.

Automated summary

This study investigated the ester-ester exchange reaction of poly(methyl acrylate) (PMA) with alkyl formate or polyester catalyzed by alkoxide. The results showed that different groups could be efficiently introduced into PMA through the transesterification reaction. In addition, a method for preparing graft copolymers by polycondensation and ester exchange reaction was explored.