Caprolactone Polymerization,Starch Oxidation And Polymer Processing In Deep Eutectic Solvents

Aimed at investigating the polymer formation,reaction,and processing in deep eutectic solvent(DES),the study was consisted of(1)Enzyme-catalyzed ring-opening polymerization of ?-caprolactone in DES,(2)Oxidation of starch in DES,and(3)Electrospraying of polymer solution with addition of DES into the mother solution.In the section of polymerization in DES,the synthesis of poly(?-caprolactone)(PCL)was conducted in DES with Novozye 435 as catalyst,and the product PCL was characterized with GPC,FT-IR,DSC,and NMR.The effects of polymerization temperature,polymerization time,type of DES,and molar ratio of the DES on polymerization yield,the molecular weight and molecular weight distribution of the product were systematically studied.In the section of oxidation of starch in DES,the oxidized starch was prepared in the DES of CHCl + ethyl glycol with 30 wt% hydrogen peroxide aqueous solution or urea hydrogen peroxide(UHP)as oxidant,and characterized by measuring the contents of-C=O and –COOH group with titration method,FT-IR,and SEM.The effects of content of oxidant,reaction time,and reaction temperature on the oxidation reaction and properties of the oxidized product were studied.In the section of electrospraying with addition of DES into the mother solution,the PMMA and PLAG particles were prepared via the electrospraying with the PMMA and PLGA as model polymer,acetonitrile and DMF as solvent of mother solution,and addition of ChCl/ethyl glycol(molar ratio of 1:4),DCM,and DMF and ChCl/glycerol(molar ratio of 1:2)into the mother solution.The morphology of product particles was characterized with SEM and the effects of the various additions were investigated.The study results showed that,(1)Synthesis of PCL: At fixed temperature and reaction time,polymerizations in different DES and in DES with different molar ratios produced PCL with different molecular weight and molecular weight distribution,which could provide an opportunity to manipulate the molecular weight and molecular weight distribution of a polymerization in DES.With the increase of reaction time and temperature,the yield and molecular weight increased while the molecular weight decreased.(2)Oxidation of starch: The contents of C=O and COOH group in the product oxidized starch from UHP were always higher than those from the 30 wt% hydrogen peroxide aqueous solution.With the increase of UHP content from 16.5% to 33%,the contents of C=O and COOH group in the product decreased.The content of C=O group did not change with time while the content of COOH reached maximum at time of 3 hours.The content of C=O group increased while the content of COOH group decreased with reaction temperature.The SEM showed that the differences of shape in the oxidized starch particles could be ignored.(3)Electrospraying: The connection between particles became more serious with more addition of DES into the electrospraying mother solution.The addition of DCM into the PMMA mother solution would lead to formation of particles with holes at low DCM concentrations and bowel-like particles at high DCM concentrations.The addition of DMF would produce spherical particles mixed with small amount of bowel-like particles at low concentrations and ellipsoidal particles mixed with small amount of bowel-like particles at high concentrations.And small holes were observed on the surface of the ellipsoidal particles.