预聚-酶催化缩聚法合成超支化聚酯及其结构表征

以丙三醇、1,6-己二醇和己二酸为共聚单体,以固定化脂肪酶Novozym435为催化剂,尝试先进行共聚单体的预聚后在有机介质中进行酶催化直接缩聚反应合成脂肪族超支化聚酯的新途径,考察了反应介质和反应温度对酶催化缩聚反应的影响,并采用凝胶渗透色谱和核磁共振确定产物的分子量和结构.结果表明,将单体的预聚与酶催化缩聚反应相结...

Synthesis of Hyperbranched Polyester by Combination of Prepolymerization with Enzymatic Condensation Polymerization and Its Characterization

A new route for hyperbranched aliphatic polyester by the prepolymerization of comonomers followed by the enzymatic condensation polymerization in organic media was developed using glycerol, 1,6-hexanediol, and adipic acid as comonomers and using immobilized lipase Novozym 435 as a biocatalyst. The organic solvents, such as isooctane, toluene, tert-butanol, tetrahydrofuran, and acetone, were used as the reaction medium for enzymatic condensation polymerization. The effects of reaction medium and reaction temperature on the enzymatic condensation polymerization were investigated. The molecular mass and the structure of the prepared polyesters were characterized by gel permeation chromatography and NMR. The results indicated that the hyperbranched aliphatic polyester could be successfully synthesized under the mild conditions by the combination of prepolymerization of comonomers with enzymatic condensation polymerization in organic media. Toluene was the best reaction medium among the examined ones, and the lipase Novozym 435 exhibited the highest activity at 70 ^oC within the temperature range from 50 to 90 ^oC. The polyester prepared by prepolymerization and the enzymatic condensation polymerization in toluene at 70 ^oC possessed the maximal molecular mass of up to 1.31×10⁴ and the branching degree of about 0.27.