【摘要】：聚碳酸酯是一種性能優(yōu)良的工程塑料,具有優(yōu)異的透明性、絕緣性及無毒性等優(yōu)點(diǎn).目前實(shí)現(xiàn)大規(guī)模工業(yè)生產(chǎn)的是雙酚A型聚碳酸酯,但是其生產(chǎn)原料雙酚A具有毒性,限制了其應(yīng)用.異山梨醇是一種生物基可再生單體,具有無毒、手性和剛性等特性,是雙酚A的理想替代品.但是異山梨醇親水性強(qiáng),且羥基的活性低,導(dǎo)致碳酸二苯酯和異山梨醇通過熔融縮聚反應(yīng)合成異山梨醇基聚碳酸酯(PIC)困難,因此選用合適的催化劑成為一個(gè)重要因素.目前報(bào)道的效果較好的催化劑是無機(jī)堿催化劑,這類催化劑催化活性差,容易引發(fā)副反應(yīng),在產(chǎn)品中殘留影響產(chǎn)品質(zhì)量.離子液體具有環(huán)境友好和陰陽離子可設(shè)計(jì)等優(yōu)點(diǎn),是無機(jī)堿催化劑的良好替代品.本文設(shè)計(jì)合成了六種季銨類的堿性離子液體(四乙銨二氰胺鹽、四乙銨咪唑鹽、四乙銨乳酸鹽、四乙銨-1,2,4-三氮唑鹽、四乙銨苯甲酸鹽和四乙銨乙酸鹽),用于催化熔融縮聚反應(yīng)合成PIC.用核磁共振表征了PIC的結(jié)構(gòu),用凝膠色譜測(cè)定了PIC的分子量,通過對(duì)比PIC的重均分子量(Mw)和異山梨醇的轉(zhuǎn)化率,研究了離子液體陰離子對(duì)催化劑活性的影響.發(fā)現(xiàn)催化活性不僅與離子液體的堿性強(qiáng)弱有關(guān),還與離子液體陰離子的配位強(qiáng)度有關(guān),催化效果最好的離子液體為四乙銨咪唑鹽(TEAI).以TEAI為催化劑對(duì)合成PIC的條件進(jìn)行了優(yōu)化,得到的最優(yōu)條件為:催化劑與異山梨醇的摩爾比為5×10~(-4),縮聚時(shí)間為5 h,縮聚溫度為240 ℃.合成PIC的Mw為25600 g/mol,異山梨醇的轉(zhuǎn)化率為92%.由于均聚物PIC分子鏈剛性大,導(dǎo)致PIC熔體粘度大,不利于聚合,為了降低PIC的剛性和提高分子量,在分子鏈中引入了柔性基團(tuán)(脂肪族二醇)來合成共聚碳酸酯(PAIC).以TEAI為催化劑,異山梨醇和脂肪族二醇投料摩爾比為1:1,通過熔融縮聚反應(yīng)合成了PAICs.利用~1H NMR和~(13)C NMR詳細(xì)表征了PAICs化學(xué)組成和微觀結(jié)構(gòu),發(fā)現(xiàn)不同脂肪族二醇的羥基活性不同,合成的PAICs分子鏈中異山梨醇和脂肪族二醇的比例與投料比有所差異,得到的共聚物為無規(guī)共聚物.此外,對(duì)PAICs進(jìn)行了凝膠色譜測(cè)試,發(fā)現(xiàn)PAICs的Mw與PIC相比均有所提高.通過差示掃描量熱儀和熱重分析儀對(duì)PIC和PAICs進(jìn)行了熱穩(wěn)定性測(cè)試.結(jié)果表明,對(duì)于不同直鏈二醇制備的PAICs,隨著二醇鏈中亞甲基數(shù)量的增加,其玻璃化轉(zhuǎn)變溫度(T_g)逐漸降低,但熱穩(wěn)定性逐漸提高;而對(duì)于用1,4-環(huán)己烷二甲醇合成的PCIC,其Tg值和熱穩(wěn)定性明顯高于直鏈脂肪族二醇共聚物.這些性能為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，

本文編號(hào)：2445870