title: L-Arabinose (pyranose and furanose rings)-branched poly (vinylalcohol): enzymatic synthesis of the sugar esters followed by free radical polymerization.
abstract: Herein this study reports the successful synthesis of a new poly(vinyl alcohol) (PVA), containing L-arabinose (L-arabinopyranose and arabinofuranose isomers) branched in only two steps: (1) production of polymerizable monomers of L-arabinose isomers (pyranose and furanose forms) through enzymatic synthesis using alkaline protease from Bacillus subtilis as catalyst and two substrates: L-arabinose and Divinyl Adipate (DVA) in N,N-dimethylformamide (DMF); (2) radical polymerization of the monomers, using an initiator system consisting of potassium persulfate and hydrogen peroxide in water. The transesterification of DVA with L-arabinose was monitored via qualitative analysis by TLC, confirming the formation of the vinyl sugar ester. The acylation occurred on the two different cyclic conformations of the L-arabinose which coexist in equilibrium: (α/β) arabinofuranose and (α/β) arabinopyranose. The acylation positions and the chemical structure of the 5-O-vinyl adipoyl L-arabinofuranose and 4-O-vinyl adipolyl L-arabinopyranose formed were determined by 13C NMR. The surface activity of the L-arabinose esters mixture (monomers) was compared with a commercial product based on phenol formaldehyde polyoxyalkylene polyamine, largely used as surfactant in many industries. FTIR spectroscopy of the sugar ester monomers and the respective polymer were compared revealing the disappearance of the vinyl group in the polymer spectrum. The polymer number-average molar mass (Mn) and the weight-average molar mass (Mw) were determined by gel permeation chromatography (GPC) presenting the following results: 2.9 × 10(4) Da and 7.2 × 10(4) Da, respectively, and polydispersity (Mw/Mn) equal to 2.48.
authors.forename: Maurício
authors.initials: M
authors.lastname: Rodrigues Borges
authors.forename: Rosangela de Carvalho
authors.initials: Rde C
authors.lastname: Balaban
mesh_terms: D001089:Arabinose / Q000737:chemistry*; D001412:Bacillus subtilis / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry*; D002384:Catalysis; D010450:Endopeptidases / Q000737:chemistry*; D004952:Esters; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D058105:Polymerization; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D058428:Silica Gel / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D004952:Esters; D005609:Free Radicals; D017680:Potassium Compounds; D013431:Sulfates; D058428:Silica Gel; C009007:potassium persulfate; D011142:Polyvinyl Alcohol; D001089:Arabinose; D006861:Hydrogen Peroxide; D010450:Endopeptidases; C087822:alkaline protease