季铵类离子液体催化熔融缩聚反应合成异山梨醇基聚碳酸酯（英文）
发布时间：2019-03-22 19:57
【摘要】：聚碳酸酯是一种性能优良的工程塑料,具有优异的透明性、绝缘性及无毒性等优点.目前实现大规模工业生产的是双酚A型聚碳酸酯,但是其生产原料双酚A具有毒性,限制了其应用.异山梨醇是一种生物基可再生单体,具有无毒、手性和刚性等特性,是双酚A的理想替代品.但是异山梨醇亲水性强,且羟基的活性低,导致碳酸二苯酯和异山梨醇通过熔融缩聚反应合成异山梨醇基聚碳酸酯(PIC)困难,因此选用合适的催化剂成为一个重要因素.目前报道的效果较好的催化剂是无机碱催化剂,这类催化剂催化活性差,容易引发副反应,在产品中残留影响产品质量.离子液体具有环境友好和阴阳离子可设计等优点,是无机碱催化剂的良好替代品.本文设计合成了六种季铵类的碱性离子液体(四乙铵二氰胺盐、四乙铵咪唑盐、四乙铵乳酸盐、四乙铵-1,2,4-三氮唑盐、四乙铵苯甲酸盐和四乙铵乙酸盐),用于催化熔融缩聚反应合成PIC.用核磁共振表征了PIC的结构,用凝胶色谱测定了PIC的分子量,通过对比PIC的重均分子量(Mw)和异山梨醇的转化率,研究了离子液体阴离子对催化剂活性的影响.发现催化活性不仅与离子液体的碱性强弱有关,还与离子液体阴离子的配位强度有关,催化效果最好的离子液体为四乙铵咪唑盐(TEAI).以TEAI为催化剂对合成PIC的条件进行了优化,得到的最优条件为:催化剂与异山梨醇的摩尔比为5×10~(-4),缩聚时间为5 h,缩聚温度为240 ℃.合成PIC的Mw为25600 g/mol,异山梨醇的转化率为92%.由于均聚物PIC分子链刚性大,导致PIC熔体粘度大,不利于聚合,为了降低PIC的刚性和提高分子量,在分子链中引入了柔性基团(脂肪族二醇)来合成共聚碳酸酯(PAIC).以TEAI为催化剂,异山梨醇和脂肪族二醇投料摩尔比为1:1,通过熔融缩聚反应合成了PAICs.利用~1H NMR和~(13)C NMR详细表征了PAICs化学组成和微观结构,发现不同脂肪族二醇的羟基活性不同,合成的PAICs分子链中异山梨醇和脂肪族二醇的比例与投料比有所差异,得到的共聚物为无规共聚物.此外,对PAICs进行了凝胶色谱测试,发现PAICs的Mw与PIC相比均有所提高.通过差示扫描量热仪和热重分析仪对PIC和PAICs进行了热稳定性测试.结果表明,对于不同直链二醇制备的PAICs,随着二醇链中亚甲基数量的增加,其玻璃化转变温度(T_g)逐渐降低,但热稳定性逐渐提高;而对于用1,4-环己烷二甲醇合成的PCIC,其Tg值和热稳定性明显高于直链脂肪族二醇共聚物.这些性能为共聚碳酸酯用作高性能聚合材料提供了可能性.
[Abstract]:Polycarbonate is a kind of engineering plastics with excellent properties, such as transparency, insulation and non-toxicity. At present, bisphenol A polycarbonate is produced on a large scale in industry, but its raw material bisphenol A is toxic, which limits its application. Isosorbide is a kind of bio-renewable monomer, which is non-toxic, chiral and rigid. Isosorbide is an ideal substitute for bisphenol A. However, the hydrophilicity of isosorbide is strong and the activity of hydroxyl group is low, so it is difficult for diphenyl carbonate and isosorbide to synthesize isosorbide-based polycarbonate (PIC) by melt Polycondensation. Therefore, it is an important factor to choose suitable catalyst for the synthesis of isosorbide-based polycarbonate. Inorganic base catalyst is the most effective catalyst reported at present. This kind of catalyst has poor catalytic activity and is easy to initiate side reactions. The residue in the product affects the quality of the product. Ionic liquids, which are environmentally friendly and can be designed by anions and cations, are good substitutes for inorganic base catalysts. Six kinds of quaternary ammonium basic ionic liquids (tetraethylammonium dicyandiamine salt, tetraethylammonium imidazole salt, tetraethylammonium lactate, tetraethylammonium-1,2,4-triazole salt, tetraethylammonium benzoate and tetraethylammonium acetate) have been designed and synthesized. Synthesis of PIC. by Catalytic Melt Polycondensation The structure of PIC was characterized by nuclear magnetic resonance (NMR). The molecular weight of PIC was determined by gel chromatography. The effect of ionic liquid anions on the activity of the catalyst was studied by comparing the heavy average molecular weight (Mw) of PIC and the conversion of isosorbide alcohol. It was found that the catalytic activity was related not only to the alkalinity of ionic liquids, but also to the coordination strength of anions in ionic liquids. The best ionic liquid was tetraethylammonium imidazolium salt (TEAI). The synthesis of PIC was optimized by using TEAI as catalyst. The optimum conditions were obtained as follows: molar ratio of catalyst to isosorbide was 5 脳 10 ~ (- 4), Polycondensation time was 5 h, and polymerization temperature was 240 鈩，
本文编号：2445870
[Abstract]:Polycarbonate is a kind of engineering plastics with excellent properties, such as transparency, insulation and non-toxicity. At present, bisphenol A polycarbonate is produced on a large scale in industry, but its raw material bisphenol A is toxic, which limits its application. Isosorbide is a kind of bio-renewable monomer, which is non-toxic, chiral and rigid. Isosorbide is an ideal substitute for bisphenol A. However, the hydrophilicity of isosorbide is strong and the activity of hydroxyl group is low, so it is difficult for diphenyl carbonate and isosorbide to synthesize isosorbide-based polycarbonate (PIC) by melt Polycondensation. Therefore, it is an important factor to choose suitable catalyst for the synthesis of isosorbide-based polycarbonate. Inorganic base catalyst is the most effective catalyst reported at present. This kind of catalyst has poor catalytic activity and is easy to initiate side reactions. The residue in the product affects the quality of the product. Ionic liquids, which are environmentally friendly and can be designed by anions and cations, are good substitutes for inorganic base catalysts. Six kinds of quaternary ammonium basic ionic liquids (tetraethylammonium dicyandiamine salt, tetraethylammonium imidazole salt, tetraethylammonium lactate, tetraethylammonium-1,2,4-triazole salt, tetraethylammonium benzoate and tetraethylammonium acetate) have been designed and synthesized. Synthesis of PIC. by Catalytic Melt Polycondensation The structure of PIC was characterized by nuclear magnetic resonance (NMR). The molecular weight of PIC was determined by gel chromatography. The effect of ionic liquid anions on the activity of the catalyst was studied by comparing the heavy average molecular weight (Mw) of PIC and the conversion of isosorbide alcohol. It was found that the catalytic activity was related not only to the alkalinity of ionic liquids, but also to the coordination strength of anions in ionic liquids. The best ionic liquid was tetraethylammonium imidazolium salt (TEAI). The synthesis of PIC was optimized by using TEAI as catalyst. The optimum conditions were obtained as follows: molar ratio of catalyst to isosorbide was 5 脳 10 ~ (- 4), Polycondensation time was 5 h, and polymerization temperature was 240 鈩，
本文编号：2445870
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