Cyclopolymerization of dimethacrylic derivatives by group transfer polymerization

Abstract

To investigate the possibility of cyclopolymerization of dimethacrylic derivatives by group transfer polymerization(GTP), 2,6-dicarbomethoxy-1,6-heptadiene (DCHD), 2,6-dinitrile-1,6-heptadiene(DNHD), and 2,5-dicarbomethoxy-1,5-hexadiene(DCHXD) were prepared and polymerized. In the study of cyclopolymerization of DCHD;DCHD was cyclopolymerized by GTP. The polymerization could be initiated by silyl enol ether in the presence of bifluoride and bibenzoate salt as a catalyst. The polymerization proceeded at room temperature and the yield of polymer was quantitative. "Living" cyclopolymerization was achieved to give a linear polymer of a cyclohexane repeat unit without network structure. The polydispersity of PDCHD was in the range of 1.23-1.28, which shows good molecular weight control. The mechanism of cyclopolymerization by GTP was proposed using a nondissociative mechanistic rationale, as intermolecular-intramolecular alternating mechanism. By using a GTP initiator, [1-methoxy-1-[(trimethylsily) oxy] methylene]cyclohexane which have a similar structure with polymer end group, it was deducted that the rate of initiation by silyl ketene acetal was not much slower than the rate of propagation. AB and ABA block copolymers of DCHD and AMA (MMA or BMA) were prepared by monofunctoinal initiators for GTP, respectively. The block copolymerization resulted in quantitative yield and low poldispersities (Mw/Mn = 1.33-1. 38). No indication of linear structure of olefinic moieties was observed in thd IR and NMR spectra of PDCHD. In the $^13C$ NMR spectrum of cyclic structure, the assignment could be accomplished by a DEPT experiment and low molecular weight analogues, e.g., cis/trans 1,3-dicarbomethoxy cyclohexane. In the study of cyclopolymerization of DNHD; GTP of DNHD was resulted in the cross-linked polymer. Even though polymerized under highly dilute conditions, the linear polymer could not be obtained. In the case of DNHD, GTP did not offer a proper method for synthesis ...