Synthesis And Property Of Poly (methyl Methac Rylate)-block-poly(methyl Acrylate)

Polymethyl acrylate（PMA）has good light transmittance and is suitable for composite glass transparent interlayers,aircraft cabin covers,windshields and other military high-transparency parts.However,the PMA material has low thermal stability and large intrinsic viscosity,which is not conducive to the processing and production of the materials.At the same time,PMMA materials are widely used in organic glass and building optical materials because of their good light transmittance.In this paper,PMMA and PMA are used for block design,because PMMA has higher thermal stability and lower intrinsic viscosity,and its purpose is to obtain organic materials with excellent performance and wide use.The general polymerization method is difficult to block the two monomers of MMA and MA,and the purpose of controlling the activity is not obtained.In this paper,a new polymerization method can be used to obtain PMMA and PMA block copolymers with controllable molecular weight and small dispersion index（PDI）.First,the block copolymerization of PMMA and Pt-BA was catalyzed by a group transfer polymerization（GTP）method using an organic catalyst to obtain a block copolymer with a controlled molecular weight and a small PDI.Second,PMMA and PAA block copolymers were obtained through the copolymer was de-t-butylized by using trifluoroacetic acid（TFA）.Finally,Trimethylsilyl diazomethane(C₄H₁₀N₂Si)was used for methylation to obtain PMMA and PMA block copolymer.This article successfully synthesized the following copolymers:（1）DP（degree of polymerization）=100-component PMMA and PMA diblock copolymers with different component ratios,molecular weights close to the theoretical value PDI between1.10 and 1.16.（2）PMMA and PMA Diblock,Tetrablock,Hexablock,Octablock,and Deblock copolymers with the same DP=100 components have molecular weights close to the theoretical value of PDI between 1.12 and 1.18.（3）The PMMA and PMA diblock copolymers with the same DP=100/200/400/600 components have molecular weights close to the theoretical value of PDI between 1.13 and 1.22.（4）DP=200 for PMA₁₀₀-b-PMMA₁₀₀,PMMA₅₀-b-PMA₁₀₀-b-PMMA₅₀,PMA₅₀-b-PMMA₁₀₀-b-PMA₅₀,PMA₅₀-b-PMMA₅₀-b-PMA₅₀-b-PMMA₅₀,PMA₅₀-b-PMMA₁₅₀,PMMA₅₀-b-PMA₁₅₀,PMMA₂₅-b-PMA₁₅₀-b-PMMA₂₅,PMA₂₅-b-PMMA₁₅₀-b-PMA₂₅ copolymer,molecular weight close to the theoretical value PDI between 1.14 and 1.28.The glass transition process of copolymers was measured by differential scanning calorimetry（DSC）,and the thermal properties of copolymers with different component proportions,multi-blocks,and different degrees of polymerization were discussed.The results show:Calculate the glass transition temperature（T_g）of the copolymer by the Fox equation（1）The highest T_g of PMMA₁₀-b-PMA₉₀ in diblock copolymers with different component ratios was 73.98°C;（2）The T_g of the Deblock copolymer in the multi-block copolymer was up to 39.99°C（3）The highest T_g of PMMA₃₀₀-b-PMA₃₀₀ in diblock copolymers with different degrees of polymerization was 42.94°C.The intrinsic viscosity of the copolymer was measured with a Viscometer,and the mean square radius of rotation of the copolymer in solution was measured with a WYATT viscosity detector.The results show:different components,different degrees of polymerization,different block modes and different chain ends affect the intrinsic viscosity and mean square radius of rotation of the copolymer.The change in the structure of the copolymer material has a greater impact on its intrinsic viscosity and T_g.Therefore,the purpose of changing the properties of the copolymer by changing the structure of the copolymer is easy to achieve.