【作者】 马敬；

【导师】 陈厚；

【作者基本信息】 鲁东大学 ， 高分子化学与物理， 2011， 硕士

【摘要】 聚丙烯腈（PAN）是一种重要的高分子材料前驱体,具有优异的物理和化学性能。窄分子量分布是合成高性能PAN的必然要求。活性可控自由基聚合能够实现聚合物分子结构的精确设计,并能对聚合物的分子量进行预测,合成窄分子量分布的聚合物,因此是制备窄分子量分布PAN的理想聚合技术。本论文分别采用电子转移产生催化剂引发原子转移自由基聚合（AGET ATRP）技术和单电子转移活性自由基聚合（SET-LRP）技术合成窄分子量分布的PAN,并通过重量法计算单体丙烯腈的转化率,采用凝胶渗透色谱（GPC）法测定分子量和分子量分布,采用核磁共振光谱（1H NMR）表征PAN的结构。采用AGET ATRP,以丙烯腈（AN）为单体,四氯化碳（CCl₄）为引发剂,溴化铜（CuBr₂）/亚氨基二乙酸（IDA）为催化剂前体,抗坏血酸（VC）为还原剂,N,N-二甲基甲酰胺（DMF）为溶剂,在均相体系中合成窄分子量分布的PAN。动力学实验表明该聚合反应为一级动力学反应,PAN的分子量随着单体转化率的增加而线性增大,并且分子量分布较窄,显示活性可控聚合特征。实验还考察了配体、催化剂、引发剂、还原剂浓度和聚合温度对聚合反应的影响。研究发现:当[AN]:[CCl₄]:[CuBr₂]:[IDA]:[VC] = 200:1:1:2:0.75时,聚合反应的可控性最好,分子量分布为1.25;聚合反应速率随着聚合温度的升高而加快,聚合反应的表观活化焓为35.9 kJ/mol。采用AGET ATRP,以AN为单体,CCl₄为引发剂,三氯化铁（FeCl₃）/乳酸（LA）为催化剂前体,VC为还原剂,DMF为溶剂,在均相体系中合成窄分子量分布的PAN。动力学实验表明该聚合反应为一级动力学,PAN的分子量随着单体转化率的增加而线性增大,并且分子量分布窄,显示活性可控聚合特征。实验还考察了配体用量、引发剂用量、聚合温度以及不同配体对聚合反应的影响。研究发现:当[AN]:[CCl₄]:[FeCl₃]:[LA]:[VC] = 200:1:1:2:0.75时,聚合反应的可控性最好,分子量分布为1.20;聚合反应速率随聚合温度的升高而加快,聚合反应的表观活化焓为32 kJ/mol。采用AGET ATRP,通过“两步加料”法,以AN为单体,CCl₄为引发剂,氯化铜（CuCl₂）为催化剂,六亚甲基四胺（HMTA）为催化剂,VC为还原剂,聚氧乙烯月桂醚（Brij35）为乳化剂,在水介质乳液相中合成窄分子量分布的PAN。动力学实验表明该聚合反应为一级动力学反应,PAN的分子量随着单体转化率的增加而线性增大,并且分子量分布较窄,显示活性可控聚合特征。实验还考察了配体用量、聚合温度和单体浓度对聚合反应的影响。研究发现:当原料配比为[AN]:[CCl₄]:[CuCl₂]:[HMTA]:[VC] = 200:2:1:2:1.5时,聚合反应的可控性较好;聚合反应速率随着聚合温度的升高而加快,聚合反应的表观活化焓为65 kJ/mol。采用SET-LRP,以AN为单体,铜粉（Cu（0））为催化剂,CCl₄为引发剂,HMTA为配体,DMF或DMF与水的混合溶液为溶剂,在25°C或65°C下在非均相体系中合成窄分子量分布的PAN。动力学实验表明,两种温度下的聚合反应均为一级动力学反应,PAN分子量随转化率的增加而线性增大,分子量分布窄,具有活性可控自由基聚合特征。实验还考察了配体用量、催化剂用量、引发剂用量以及溶剂对聚合反应的影响。研究发现,单体转化率随配体HMTA浓度的增大而增大,当不加HMTA时,由于Cu（I）的歧化能力较弱,聚合反应几乎不发生;增大催化体系Cu（0）/HMTA的浓度,聚合反应速率加快,加入减活剂CuCl₂,聚合反应的可控性提高;单体转化率随CCl₄浓度增大而增大;水能提高混合溶剂的极性,进而加快聚合反应速率。更多还原

【Abstract】 Polyacrylonitrile （PAN） is an important polymer precursor that possesses outstanding chemical and physical properties. Narrow polydispersity is an essential requirement for synthesis of high-performance PAN. The living/controlled radical polymerization proves to be the desired polymerization technique for PAN with low polydispersity, since it provides a route to the facile synthesis of well-defined polymers with definite architecture, predetermined molecular weight and narrow molecular weight distribution. In this ariticle, narrow polydispersity PAN was synthesized via activator generated by electron transfer for atom transfer radical polymerization （AGET ATRP） and single electron transfer living radical polymerization （SET-LRP）, respectively. The conversion was determined gravimetrically. The molecular weight and polydispersity index （PDI） of polymers were measured by gel permeation chromatography （GPC）. The end-group of PAN was investigated via 1HNMR.Narrow polydispersity PAN was prepared via AGET ATRP in homogeneous system. The polymerization was conducted with acrylonitrile （AN） as the monomer, carbon tetrachloride （CCl₄） as the initiator, copper bromide （CuBr₂）/iminodiacetic acid （IDA） as the catalyst precursor and ascorbic acid （VC） as the reducing agent in solvent N,N-dimethylformamide （DMF）. The first order kinetic plot demonstrated the features of living/controlled polymerization as evidenced by a linear increase of molecular weight with respect to monomer conversion and narrow molecular weight distribution. The effects of the amount of ligand, catalyst, initiator as well as reducing agent and polymerization temperature on the polymerization were also investigated. The experiments results showed that the ratio of [AN]:[CCl₄]:[CuBr₂]:[IDA]:[VC]=200:1:1:2:0.75 gave the best control on the polymerization with PDI at 1.25. The polymerization rate increased with increasing the polymerization temperature. The apparent activation enthalpy was calculated to be 35.9 kJ/mol.Narrow polydispersity PAN was prepared via AGET ATRP in in homogeneous system. The polymerization was carried out with AN as the monomer, CCl₄ as the initiator, ferric trichloride （FeCl₃）/lactic acid （LA） as the catalyst precursor and VC as the reducing agent in solvent DMF. The first order kinetic plot demonstrated the features of living/controlled polymerization as evidenced by a linear increase of molecular weight with respect to monomer conversion and narrow molecular weight distribution. The effects of the amount of ligand and initiator, polymerization temperature and different ligands on the polymerization were also studied. When the ratio of [AN]:[CCl₄]:[FeCl₃]:[LA]:[VC]=200:1:1:2:0.75, the polymerization showed the best control over the molecular weight distribution and PDI=1.20. Increasing the polymerization temperature could enhance the polymerization rate. The apparent activation enthalpy was calculated to be 32 kJ/mol.Narrow polydispersity PAN was prepared via AGET ATRP in emulsion using the procedure of“two-step”. The polymerization was conducted with AN as the monomer, CCl₄ as the initator, copper chloride （CuCl₂）/hexamethylenetetramine （HMTA） as the catalyst, VC as the reducing agent and polyoxyethylene lauryl ether （Brij 35） as the surfactant. The first order kinetic plot demonstrated the features of living/controlled polymerization as evidenced by a linear increase of molecular weight with respect to monomer conversion and narrow molecular weight distribution. The effects of the amount of ligand and monomer as well as polymerization temperature on the polymerization were also discussed. The experiments results demonstrated that the suitable crude ratio of [AN]:[CCl₄]:[CuCl₂]:[HMTA]:[VC] was 200:2:1:2:1.5. The polymerization rate increased with the increase of polymerization temperature. The apparent activation enthalpy was calculated to be 65 kJ/mol.Narrow polydispersity PAN was prepared via SET-LRP in heterogeneous system. The polymerization was carried out with AN as the monomer, Cu（0） power as the catalyst, CCl₄ as the initiator and HMTA as the ligand in solvent DMF or mixture of DMF and H₂O at 25°C or 65°C. The first order kinetic plots at both temperatures demonstrated the features of living/controlled polymerization as evidenced by a linear increase of molecular weight with monomer conversion and narrow molecular weight distribution. The effects of the amount of ligand, catalyst, initiator and solvent on the polymerization were also probed. The experiments results demonstrated that monomer conversion increased with the increase of ligand. Almost no polymerization occured in the absence of ligand due to the poor disproportionation reaction of Cu（I）. The polymerization rate exhibited an increase with the increase of the amount of catalyst Cu（0）/HMTA. Better control on the molecular weight distribution was produced with the addition of CuCl₂. The polymerization rate increased with increasing the amount of CCl₄. H₂O enhanced the polarity of mixted solvent, and further led to the increase of polymerization rate.更多还原