Study On Synthesis Of Star-shaped Polyacrylates By Group Transfer Polymerization

Acrylic polymers are currently one of the most widely used polymer materials,which can be used in various industries such as daily necessities,home appliances,medicine,and chemicals.Because of its special branched structure,star-shaped polymers have unique physical and chemical properties compared to linear polymers.It also has good reactivity and versatility which makes them have a very broad application prospects.In this thesis,a new type of GTP method is used to synthesize star-shaped acrylate polymers,under the catalysis of organic catalysts based on hydrosilylation-promoted group transfer polymerization,and use this method to directly generate initiators in the reaction system.It avoids the influence of the instability of the initiator on the polymerization result.At the same time,the organic catalyst also has the advantages of environmental friendliness,low cost and easy recycling.Therefore,the use of this GTP method to synthesize star-shaped acrylic polymers is of great significance.In this thesis,two types of star-shaped latent initiators(s-TIG_n and s-CRT_n)are designed and synthesized.Hydrosilylation-promoted group transfer polymerization is used to accurately synthesize star-shaped polymethyl methacrylate(s-PMMA_n)and star-shaped polybutyl acrylate(s-PnBA_n).They have different numbers of arms and different degrees of polymerization.(1)Using acid alcohol esterification method,reacting 1,1,1-trimethy-lolpropane,pentaerythritol,and dipentaerythritol with tiglic acid and croconic acid to prepare 3,4,6 armed s-TIG_n and s-CRT_n,tested by NMR and elemental analysis,shows that its structure is clear and its purity is high.(2)Using B(C₆F₅)₃ as a catalyst,s-TIG_n and Me₂Ph Si H are used for 1,4-hydrosilation reaction to generate the corresponding initiator s-SKA_n,and then with MMA in Me₃Si NTf₂ catalyzed group transfer polymerization reaction,s-PMMA_n was synthesized.The optimal polymerization conditions were explored,and the structure,molecular weight and molecular weight distribution of s-PMMA_n were characterized by ¹H NMR and SEC.The results showed that the obtained polymer has a clear structure and a narrow molecular weight distribution(M_w/M_n between 1.07 and 1.21).This shows that s-TIG_n,as a latent initiator,can be applied to the polymerization reaction system and prepare s-PMMA_n with a controllable molecular weight and a narrow molecular weight distribution.(3)Using B(C₆F₅)₃ as a catalyst,s-CRT_n and Me₂Ph Si H are used for1,4-hydrosilation reaction to generate the corresponding initiator s-SKA_n,and then with MMA in B(C₆F₅)₃ catalyzed group transfer polymerization reaction,s-PnBA_n was synthesized.The optimal polymerization conditions were explored,and the structure,molecular weight and molecular weight distribution of s-PnBA_n were characterized by ¹H NMR and SEC.The results showed that the obtained polymer has a clear structure and a narrow molecular weight distribution(M_w/M_n between 1.08 and 1.21).This shows that s-CRT_n,as a latent initiator,can be applied to the polymerization reaction system and prepare s-PnBA_n with a controllable molecular weight and a narrow molecular weight distribution.