Organocatalyzed ring-opening copolymerization of ?-bromo-?-butyrolactone with ?-caprolactone for the synthesis of functional aliphatic polyesters - pre-polymers for graft copolymerization.

ABSTRACT: Diphenyl phosphate (DPP) was exploited as an organocatalyst to synthesize copolymers by ring-opening polymerization with ?-bromo-?-butyrolactone (?Br?BL) and ?-caprolactone (?CL) as monomers and polyethylene glycol (PEG) as initiator. The conversion rates of monomers and molecular weights of copolymers synthesized under different conditions were determined by ¹H-NMR. The ¹H-NMR results showed that the copolymers of ?Br?BL and ?CL initiated by PEG (PEGCB) were successfully synthesized and the conversions of ?CL were relatively high (?70%), while the conversions of ?Br?BL were relatively low (?26%). The highest molar ratio of ?Br?BL to ?CL units in these copolymers is 0.17, when the copolymerization was carried out at 100? for 17h. The bromine atoms hanged on the chain of the copolymers PEGCB provide a good opportunity to construct graft copolymers via atom transfer radical polymerization (ATRP). The subsequent grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) was conducted by using PEGCB3 as macroinitiator, CuBr/N,N',N',N",N"- pentamethyldiethylenetriamine (PMDETA) as catalysts and toluene/anisole as solvents via ATRP. According to the analysis of ¹H-NMR, the grafting efficiency, grafting ratio and grafting frequency were 22.4%, 160.7% and 1133.8, respectively.

SUBMITTER: Gao C 

PROVIDER: S-EPMC6282472 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature