超声法合成聚[2-甲氧基-5-(2′-乙基己氧基)-对亚苯基亚乙烯基]的研究

采用超声合成方法,以对甲氧基苯酚为起始原料,经醚化、溴甲基化和聚合反应,得到无凝胶、完全可溶、高分子量的聚(2-甲氧基-5-(2′-乙基己氧基)-对亚苯基亚乙烯基)(MEH-PPV),其数均分子量高达9.5×105,分子量分布为2.4.并通过核磁共振氢谱(1H-NMR)和红外光谱进行了结构表征.与常规的机械搅拌反应相比,超声合成方法具有反应时间短、反应温度低、产率高、聚合物分子量较大等特点,特别是这种方法有效抑制了聚合过程中的凝胶化问题,合成的MEH-PPV具有更高的荧光量子效率.

ULTRASONIC SYNTHESIS OF POLY[2-METHOXY-5-(2′-ETHYLHEXYLOXY)-p-PHENYLENEVINYLENE]

Poly2-methoxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene](MEH-PPV) is a typical example of solution processable conjugated polymers for polymeric light emitting diodes application,which shows good solubility in common organic solvents.However,gelation or micro-gelation always occurs during the polymerization process.Herein,we report the synthesis of fully soluble MEH-PPV by ultrasonic irradiation method.The raw material was 4-methoxyphenol,and ultrasonic irradiation method was used in the etherification,bromomethylation and polymerization.The polymer is prepared from the bis-bromomethyl monomer through the Gilch route.Compared with the conventional mechanical stirring,ultrasonic irradiation method has shown great advantages with respect to the shorter reaction time,lower reaction temperature,higher yields and higher molecular weight(M_n) of MEH-PPV.The optimized reaction conditions including reaction solvent,temperature,and time,were determined for the related etherification,bromomethylation and polymerization with ultrasonic method.Especially,using ultrasonic method,the gelatification in the polymerization had been overcome.MEH-PPV obtained was fully soluble in THF and chloroform and no gel or micro-gel existed.The structures of the intermediate products and MEH-PPV were determined by IR and~1H-NMR.It was found the MEH-PPV synthesized by ultrasonic irradiation processes had higher luminescence quantum efficiency than that by mechanical stirring.