Tailored glycopolymers

[摘要] The synthesis of glycopolymers with various comonomers as prepared via the RAFT process isinvestigated.The macro-RAFT agent poly(3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-D-glucofuranose)(PMAlpGlc) was prepared by polymerization of the glycomonomer with cumyl phenyl dithioacetateas the chain transfer agent. Chain extension with styrene or methyl acrylate or acrylic acid affordednovel diblock copolymers, (PMAlGlc-b-poly[styrene] or PMAGlc-b-poly[methyl acrylate] orPMAlGlc-b-poly[acrylic acid]), with predetermined molecular weights and narrow molecular weightdistributions.The poly(acrylic acid) based glycopolymer was used to modify the surface of CaCO3, formingwhat will be referred to as a 'sugar-coated CaCO3' particle. This surface modifying effect wasevaluated in depth; a schematic study of the effect of reaction temperature, pH, reaction time andglycopolymer concentration on CaCO3 crystallization was carried out. The analytical techniquesThermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) were used to verifythat these 'sugar-coated CaCO3' particles have an increased adherence to cellulose compared to 'nonsugar-coated' particles.A series of polymer configurations comprising various ratios of glycomoiety to poly(acrylic acid)was prepared. The effect of this polymer series on CaCO3 crystallization was evaluated and the idealpolymer configuration and its optimum synthesis conditions (i.e. reaction pH, temperature, time andpolymer concentration) that gave maximum adherence of the 'sugar-coated CaCO3' particle ontocellulose were identified.The ability of these poly(acrylic acid) based glycopolymers to increase the interaction betweenCaCO3 and cellulose was then evaluated. This was done by simply mixing all three substrates, i.e.glycopolymer, cellulose and CaCO3 together. Analysis by TGA, SEM and Thin LayerChromatography (TLC) revealed both the ideal polymer configuration that favoured increased adherence of the CaCO3 to cellulose and the optimum reaction conditions required for application andtesting.In addition to studying the interaction between cellulose and CaCO3, the amphiphilic nature ofthe glycopolymers was determined. Transmission Electron Microscopy (TEM) confirmed that coreshellparticles were prepared and that these particles are solvent exchangeable (in the case of styreneand methyl acrylate glyco-blocks) or pH exchangeable (in the case of acrylic acid glyco-blocks).

[发布机构] Stellenbosch University