Synthesis Of Styrene/Diene Thermoplastic Elastomer Based On Modular Synthesis Method

With the continuous development of basic and applied research in polymer science,the needs are increasing for the precise regulation of polymer structures at all levels.How to design accurate and efficient synthesis methods to achieve the precise regulation of polymer structure at all levels is an urgent problem that needs to be solved in the research of polymer chemistry.Combination of orthogonal reaction and living anionic polymerization is a feasible approach.Utilizing small molecules brick or polymeric brick with clickable functional groups as the basic modules of the synthetic methods,to develop precise synthesis method based on modular synthesis of polymers to achieve accurate regulation of short-range structures like sequence,function,topological structure and long-range structures like chain assembly,chain folding and helix structure is an essential way to develop precise synthesis strategy.This dissertation focused on modular synthesis method.Through synthesizing monomeric and polymeric building blocks carrying clickable functional groups（like silicone hydrogen,amino and alkyne groups）,utilizing Ugi four components reaction,hydrosilylation and thiol-yne click reaction to deal with difficulties in precise polymers synthesis area making use of multi kinds of building blocks.The main research results are as follows:（1）Combining Ugi-4CR and hydrosilylation as an orthogonal reaction cycle,utilizing 3-dimethylsilylaniline（3DA）and 4-dimethysilylaniline（4DA）as isomeric building block in Ugi-4CR and hydrosilylation orthogonal cycle,four discrete oligomers with same chemical composition and molecular weight but different isomeric unit was obtained,synthetic method-based on UHOC toward discrete oligomers was established.Research shows that discrete 6mer with para linkage unit exhibits larger molecular dimension and higher temperature of glass transition（T_g）.Regulating the sequence of isomeric unit in the molecular chain,discrete oligomers with same molecular weight and chemical composition but different tectonic sequence were fabricated.The regulation method of chain folding was discussed,para linker forces the chain to fold in vertical direction and meta linker forces the chain to extent in parallel direction.The radius of gyration（R_g）（Δ=2.4（?））and T_g（Δ=16.1°C）of oligomers show obvious difference depended on chain folding method.Tectonic sequence which differs from conventional sequence concept like monomer sequence and stereo sequence was proposed.The tectonic sequence directed chain folding was achieved.（2）Living anionic polymerized Si H/dialkyne functionalized polystyrene polymeric brick was synthesized（M_w was 5.7 kg/mol,average number of Si H/alkyne was 1.0/2.0）.Hyper Macs was obtained via hydrosilylation of polymeric brick,hyperbranched structure was determined with Dp_w（5.3～39.7）and branching factor（0.33～0.52）.Different types of alkynes（Double alkyne-DA and mono alkyne-MA）were labelled with pyrene group by thiol-yne click reaction,topological functionalization was achieved.Through fluorescence test of pyrene labelled Hyper Macs,calibration curve of the ratio of fluorescence intensity of pyrene excimer and monomer（I_E/I_M）to the proportion of DA(f _DA)was built,the f _DA of hyperbranched polymer was found on the calibration curve.It is proved that hyperbranched polystyrene with nearly perfect dendritic branching structure(f _DA=0.99)can be obtained via the modular synthesis method.（3）Well-defined Si H/NH₂ functionalized polystyrene brick was synthesized via living anionic polymerization（LAP）,the M_n was 3.0 kg/mol,average numbers of Si H/NH₂ were 1.0.G2-Dendri Mac was obtained with Ugi-4CR and hydrosilylation cycles,the M_n of G2Dendri Mac was 50.9 kg/mol.Si H/alkyne functionalized polybutadiene Si H-PB-yne₂ and PS-Si H bricks were obtained using LAP,through hydrosilylation of polymeric brick,hyperbranched PB（Hyper PB）was obtained with g’0.36,utilizing modular synthesis methodology,hyperbranched Styrene-Butadiene-Styrene triblock polymers（SBS）was constructed via hydrosilylation of Hyper PB and PS-Si H.Hyperbranched SEBS was finally obtained through hydrogenation.The conversion of hydrogenation was 99.8%.The modular synthesis of hyperbranched elastomers were achieved.Hyper SEBS was used to toughen SEBS1651,the blend of Hyper SEBS:SEBS1651=1:19 exhibits 22.0%higher tensile strength and elongation at break increases from 450%to 550%.