Accelerated Biodegradation of Poly(vinyl alcohol) by Glycosidations of the Hydroxyl Groups or Addition of Sugars

Abstract

Biodegradabilities of N-acetyl-d-glucosamine (GlcNAc)- (1) and chitobiose-substituted (2) poly(vinyl alcohol)s (PVA)s in a soil suspension (pH 6.5) were investigated at 25 degrees C for 40 days. Biochemical oxygen demand of 1 with a degree of substitution of 0.2-0.3 (DP = 430-480) was higher than that of PVA under the degradation condition. Size exclusion chromatography, (1)H NMR, and Fourier-transform infrared measurements of the recovered sample indicated that biodegradation of the PVA main chain was accelerated by partial glycosidation of hydroxyl groups in PVA. Similar acceleration was observed in a PVA/GlcNAc (50:50, w/w) mixture. Microbes which relate with degradation of the glycosidated polymers were grown in a culture medium including the soil suspension and the polymer as the carbon source. Polyacrylamide gel electrophoresis (SDS-PAGE) and IR measurements indicated that a cell-free extract derived from GlcNAc-substituted PVA was different from that in the PVA/GlcNAc mixture. The results suggested that the PVA main chain in GlcNAc-substituted PVA was cleaved by a different microorganism or via a mechanism different from that in the mixture. Chitobiose-substituted PVA 2 showed more enhanced acceleration, indicating that the sugar length influenced the degradability.

Poly(Vinyl Alcohol) Physical Hydrogels: New Vista on a Long Serving Biomaterial

“…In another report, chemical modification of PVA by glycosylation was achieved using oxazoline derivatives of triacetylated sugar, e.g. N ‐acetyl‐ D ‐glucosamine (GlcNAc) or chitobiose,71, 72 with subsequent deacetylation to yield GlcNAc and chitobiose‐PVA conjugates.…”

Preparation and Biodegradation of Sugar‐Containing Poly(vinyl acetate) Emulsions

“…Furthermore, our results showed that the biodegradability of the PVAc‐based hybrid emulsion was higher than that of the PVAc emulsion, in which the PVAc part was biodegraded via saponification, transforming to poly(vinyl alcohol) (PVA) segments and successive oxidation and chain scission in the sludge 7. Also, we reported the hastened biodegradation of PVA by direct glycosidation of the hydroxyl groups,8, 9 in which biochemical oxygen demand (BOD), size exclusion chromatography (SEC), infrared (IR) spectroscopy, NMR spectroscopy and electrophoresis (SDS‐PAGE) analyses supported that partially glycosidations were effective for controlling the biodegradation of PVA main chains. In the present study, we prepared sugar‐containing PVAc emulsions by seeded emulsion copolymerizations of glycosylated vinyl monomers and VAc in the presence of poly(BS‐ co ‐BA) and investigated their biodegradabilities using BOD, SEC, IR and NMR measurements.…”

“…In the other route, direct cleavage of β ‐hydroxy ketone segments occurs via a reverse aldol reaction and produces a methyl ketone and aldehydes, in which the key protein is PVA dehydrogenase (PVADH) with 67 kDa 21. In our previous reports dealing with the accelerated biodegradation of PVA by direct glycosidation,8, 9 the recovered sample was analyzed by IR spectroscopy, in which ketone and β ‐diketone structures were observed, suggesting that main chain scission of sugar‐substituted PVA occurred by hydrolysis16, 17 or a reverse aldol reaction21 followed by oxidation. In this work, the IR spectrum of the recovered PVAc‐based emulsion film after biodegradation was similar to PVA [3 418 cm −1 ( ν OH ), 2 922 cm −1 ( ν CH ), 1 044 cm −1 ( ν CO )], except for absorptions at 1 715 and 1 651 cm −1 as shoulder bands, which were identified with those of ketone and β ‐diketone structures, respectively.…”

Glycopolymers obtained by chemical modification of well‐defined block copolymers

“…There are mainly two approaches to prepare glycopolymers;20 by either polymerization of carbohydrate‐containing monomers25–36 or by the postpolymerization chemical modification of synthetic polymers 37–51. The first one includes the synthesis of glycomonomers protected or unprotected by using standard chemical modification15, 16, 19, 52 or click chemistry approaches20, 53–56 and posterior polymerization using different methodologies; that is, conventional and controlled radical polymerization, living anionic polymerization, cyanoxyl mediated polymerization, ring opening polymerization or combination of different techniques 25–36.…”