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193

Macromolecules. 2001:34:3527-3533.DOI: 10.1021/ma0100246

Copolymerizations of omega-pentadecalactone and trimethylene carbonate by chemical and lipase catalysis

Kumar, A; Garg, K; Gross, RA
Copolymerizations of omega -pentadecalactone (PDL) with trimethylene carbonate (TMC) were studied using chemical and enzyme catalysts. By using stannous octanoate, methylaluminoxane (MAO), or aluminum isopropoxide, copolymerizations of PDL with TMC with 1:1 feed ratio resulted in either homo-polyTMC or PDL/TMC block copolymers. These catalysts polymerize TMC more rapidly than PDL. A copolymerization catalyzed by MAO gave poly(TMC-co-16 mol % PDL) with M-n 26.4 x 10(3)g/mol and randomness numder (B) about 1.1. The sodium ethoxide-catalyzed copolymerization led to products with low M-n (<6.8 x 10(3)) but nearly random sequence distribution. The copolymerization of PDL with TMC was also studied by using lipase catalysts. Of the six lipases evaluated for PDL/TMC copolymerizations in toluene at 70 degreesC, an immobilized form of lipase B from Candida antarctica (Novozyme-435) was preferred. Changing the PDL/TMC comonomer feed ratio from 1:10 to 10:1 (mol/mol) provided copolymers that ranged in M, and PDL mol % from 7.3 x 10(3) to 25.2 x 10(3) and 28 to 88, respectively. In contrast to the chemical catalyst systems, Novozyme-435 catalysis showed that PDL was consumed more rapidly than TMC. Also, in contrast to most of the chemical catalysts, H-1 and C-13 NMR analyses showed that the copolymers from Novozyme-435 catalysis were able to give a random distribution of the repeat units at extended reaction times. Furthermore, in contrast to TMC polymerization in the presence of preformed polyPDL with MAO, Novozyme-435 catalyzed polymerization led to random copolymers.
ISI:000168833000007
ISSN: 0024-9297
CID: 3647132
Polymer preprints. 2001:41(2):1830-1831.DOI:

Lipase-catalysis facilitates coopolymerixations that were othewise difficult or impossible tby alternate chemical approaches

Kumar, A; Garg, Karan; Gao, W; Gross, RA
ORIGINAL:0013270
ISSN: 0032-3934
CID: 3649452
Abstracts of papers (American Chemical Society). 2000:220:U305-U305.DOI:

Lipase-catalysis facilitates copolymerizations that were otherwise difficult or impossible by alternative chemical approaches. [Meeting Abstract]

Kumar, A; Garg, K; Gao, W; Gross, RA
ISI:000166091301740
ISSN: 0065-7727
CID: 3647122