聚酰胺1的绿色合成方法及其电畴效应研究

Polyamide 1 (PA1) has the highest density of –HNCO– group and hydrogen bond in the odd-number nylon family, and PA1 owns the maximum dipole concentration when the molecular chain is arranged into zigzag structure. Therefore, it is expected to be an ideal energy storage material and piezoelectric material. Firstly, urea is used as the main raw material and appropriate auxiliaries are selected in this project. The CO2 can directly take part in the reactions to synthesize PA1 under supercritical CO2 condition. The synthetic conditions and influencing factors are systematically studied and the structures are comprehensively characterized. Thus, a green synthetic method for PA1 is developed. Secondly, the composites of organic piezoelectric functional materials are prepared by compounding PA1 with traditional piezoelectric polymers PA11 and PVDF. The effects of PA1 content, interface state, particle size and processing conditions on its structures and properties are investigated, which provide theoretical basis for the preparation of high-performance organic piezoelectric materials. Thirdly, in order to prepare ultra-thin flexible piezoelectric film, PA1-PA11 copolymer is prepared by copolymerization of PA1’ oligomer and amino undecarboxylic acid. Furthermore, the effects of PA1 polymerization degree, content, polymerization process and post-treatment conditions on dielectric properties, piezoelectric properties and physical-mechanical properties of copolymer films were studied; meanwhile, the microscopic mechanism is also discussed. The above researches lay a good foundation for breaking through the technical bottleneck of the production of flexible and high-performance piezoelectric thin films.

鉴于聚酰胺1（PA1）具有聚酰胺系列中最高密度的酰胺键和氢键，分子链排列成锯齿状结构时呈现最大偶极子浓度。可望成为理想的储能、压电材料。本项目首先以尿素为主要原料，选择适当助剂，在超临界CO2条件下，使CO2直接参加反应合成PA1。并对合成工艺条件和影响因素进行系统研究和结构表征。从而开发PA1的一种绿色合成方法；其次，通过将PA1与传统压电聚合物PA11和PVDF复合改性，制成复合有机压电功能材料，探讨PA1含量，界面状态，颗粒尺寸，加工处理条件对其结构和性能的影响规律，为制备高性能的有机压电材料提供理论依据；第三，为制备超薄柔性压电薄膜，采用合成的PA1的低聚物与氨基十一羧酸共聚，制备PA1-PA11共聚物，研究PA1的聚合度，含量，聚合工艺，后处理条件等因素对共聚物薄膜的介电性能，压电性能及物理机械性能的影响，并探讨其微观机理。为突破掣肘柔性高性能压电薄膜的制备技术瓶颈打下良好基础。

新能源和功能器件的发展需要突破电功能材料的诸多瓶颈，全有机聚合物是最有希望实现大面积制备柔性超高储能的电功能材料。鉴于尼龙1（PA1）具有尼龙系列中最高密度的酰胺键和氢键，可望成为理想的储能材料或压电材料。 .本项目首先以尿素为主要原料，在CO2超临界条件下，实现多组份一锅法成功合成了PA1。研究结果表明，在110℃-150℃的超临界CO2预缩合，再用200℃进行热处理，可得到不同分子量的PA1；PA1玻璃化转变温度高于100℃，随着分子量的增加，PA1在28°附近的衍射峰逐渐变小。计算对比PA1分子链之间模拟形成“六元环”和“十元环”氢键模型的能量情况表明，“六元环”模型的能量远高于“十元环”氢键模型。说明PA1形成“十元环”氢键模型的可能性更大，有利于PA1电性能的展示。.其次，系统研究了相转变和介电性能。结果表明，PA1升温至175 ℃，从铁电相转变为顺电相。且PA1的相转变具有“不可逆”性。PA1介电常数明显高于其他奇数尼龙，介电损耗则保持较低水平。同时，将PA1作为改性功能体，成功制备了PA11/PA1复合物和PVDF/PA1复合物。研究表明， PA1对PA11和PVDF基材的相容性好。可使PA11和PVDF的结晶速度和结晶度得到显著提高，且PA1的添加有利于PVDF的β晶型的形成，该结果对PVDF的电性能的改进具有重要意义。此外，PA1的添加也可显著提高PVDF和PA11的介电常数和铁电性能（剩余极化强度）。.第三，通过二元酸封端PA1和共缩聚方法，制备了不同PA1含量的共聚尼龙PA1-11。研究表明，尼龙1的引入破坏了PA11分子链的规整性，在PA1-11的分子链中形成了热力学稳定的扭曲链结构，PA1-11具有比PA11更低的熔点和结晶度。同时，随着尼龙1含量的增加，PA1-11的介电常数和击穿强度增加，介电损耗随之降低。.最后，通过研究PA1-PA11共聚体的铁电性能表明，PA1-PA1超薄压电膜的铁电性能不如预期的优异。PA1结构并不具备在电场下翻转的特性。为此，本项目还设计合成了PA1-哌嗪共聚尼龙，得到了高介电，低损耗的介电聚合物，并研究了其结构与性能。