连续微波辐射法合成聚D,L-乳酸

采用微波辐射法,以D,L-丙交酯(DLLA)为单体开环聚合合成了聚D,L-乳酸(PDLLA)。考察了催化剂种类和用量、微波辐射功率和时间对PDLLA相对分子质量的影响;用多角度激光散射仪、傅里叶变换红外光谱和核磁共振等技术对PDLLA进行了表征;并测定了反应过程中体系温度的变化。实验结果表明,以连续发射微波的改装微波炉为反应器,在Sn(Oct)2催化剂用量0.56%(以DLLA单体质量计)、辐射功率90W、辐射时间10min的条件下,合成的PDLLA的黏均相对分子质量为159.2kg/mol,收率为81.8%。改装的微波炉可连续发射微波,体系升温迅速,温升过程平稳。

Synthesis of Poly(D,L-Lactide) Under Continuous Microwave Irradiation

Ring-opening polymerization of D,L-lactide(DLLA)was studied to synthesize poly(D,L-lactide)(PDLLA)by continuous microwave irradiation in a modified domestic microwave oven.Effects of catalyst types and dosage,microwave irradiation power and irradiation time on relative molecular mass of PDLLA were investigated.PDLLA was characterized by means of MALLS,FTIR and 1H NMR.Temperature variation in the oven during reaction was measured to show advantage of continuous microwave irradiation.PDLLA with viscosity-average relative molecular mass of 159.2 kg/mol and yield of 81.8% could be obtained from DLLA under continuous microwave irradiation of 90 W for 10 min,with Sn(Oct)2 as catalyst and its dosage 0.56%(mass fraction based on DLLA monomer mass).Due to non-interrupted emission of microwave,temperature of reaction system increased more rapidly in modified domestic microwave oven,which was preferable to the conventional one.