Biocatalytic synthesis of polymers. II. Preparation of [AA–BB]_x polyesters by porcine pancreatic lipase catalyzed transesterification in anhydrous, low polarity organic solvents

Abstract

SynopsisEnzyme-catalyzed preparation of polymers offers several potentially valuable advantages over the usual polymerization procedures. (1) Such polymerizations may allow the polymer to retain functionality that would be destroyed under normal polymerization conditions. (2) The selectivity provided by enzyme catalysts may permit polymers, including optically active polymers, to be prepared that are either not accessible or accessible only with difficulty by other methods. (3) The characteristics of the enzyme and the mild polymerization conditions may permit formation of polymers having highly regular sizes and backbone structures. This report describes the first successful use of an enzyme-catalyzed polycondensation to prepare a chiral (AA-BB), polyesters of more than a few repeat units. Polymerization of bis(2,2,2-trichloroethyl) alkanedioates (BB) with diols (AA) using the enzyme porcine pancreatic lipase (PPL) as a catalyst is detailed. The polycondensations were carried out at ambient temperature in anhydrous, low polarity organic solvents such as ether, THF, and methylene chloride. End group analysis by NMR provided M,, values of 1300-8200 daltons while GPC provided M , values of 2800-14900 daltons for the polymers. Based on proton NMR spectra obtained during the polymerization, relatively rapid formation of an AA-BB "dimer" and an AA-BB-AA " trimer," slower formation of a BB-AA-BB "trimer," and subsequent condensation of these to give higher polymers are suggested to be components of the polymerization mechanism.

Recent Developments in Lipase‐Catalyzed Synthesis of Polyesters

“…[117] Polycondensation of bis(2,2,2-trifluoroethyl) adipate with sucrose catalyzed by an alkaline protease from a Bacillus sp. showing esterase activity resulted in an alternating linear polyester with M n value around 1 600 at a low yield (Scheme 27).…”

Combinatorial array‐based enzymatic polyester synthesis

“…The use of enzymes as catalysts for polymer synthesis has grown tremendously in recent years (Chaudhary et al, 1997a(Chaudhary et al, , 1997bDordick 1992;Gross et al, 1998;Kobayashi, 1999) and encompasses a wide range of polyphenols (Akkara et al, 2000;Dordick et al, 1987;Tonami et al, 1999;Wu et al, 2000), polyesters (Binns et al, 1993;Geresh and Gilboa, 1990;Kumar et al, 2000;Mesiano et al, 2000;Namekawa et al, 1999;Wallace and Morrow, 1989), and polysaccharides (Kobayashi et al, 1996). Coupled with chemoenzymatic techniques, the scope of biocatalytic polymer synthesis expands even further to include poly(acrylates, acetylenes, ols) among others.…”

Chemoenzymatic synthesis of an AB‐type diblock copolymer combining enzymatic self‐condensation polymerization and atom transfer radical polymerization

“…5,6,8 SCP of the activated x-hydroxyester with TCE in the presence of Novozyme 435 has not yet been extensively investigated, so its feasibility must be first validated. Our group selected 1 (Scheme 1) as a model system for enzyme-catalyzed condensation polymerization.…”

“…Biocatalytic approaches have been employed in the design and fabrication of various polyesters with different structures for increasing demands. 1,2 For example, Novozyme 435 (immobilized Candida antarctica lipase B) has been recognized widely as an effective and versatile biocatalyst in polyester synthesis via both ring-opening polymerization (ROP) of lactones (e.g., -caprolactone) 3,4 and polycondensation of either diacid (its derivatives)/diol combinations [5][6][7] or hydroxyacid (its derivatives); 4,8 furthermore, its scope has been further widened by the preparation of block copolymers 9,10 and hyperbranched copolymers. 11 However, the full exploitation of biocatalysis in polymer synthesis will require the development of mutually compatible chemo-and biocatalytic methods.…”