NaBH_(4)/LaCl_(3)还原体系制备液体端羟基氟橡胶  

Preparation of Hydroxyl-Terminated Liquid Fluoroelastomer with NaBH_(4)/LaCl_(3)

作　　者：李东翰 段佳玉[2] 于璐 杨晨 王婧 温相朋 LI Dong-han;DUAN Jia-yu;YU Lu;YANG Chen;WANG Jing;WEN Xiang-peng(College of Materials Science and Engineering,Shenyang University of Chemical Technology,Shenyang 110142,China;Liaoning Provincial Key Laboratory of Rubber&Elastomer,Shenyang University of Chemical Technology,Shenyang 110142,China)

机构地区：[1]沈阳化工大学材料科学与工程学院,辽宁沈阳110142 [2]沈阳化工大学辽宁省橡胶弹性体重点实验室,辽宁沈阳110142

出　　处：《沈阳化工大学学报》2021年第1期47-53,共7页Journal of Shenyang University of Chemical Technology

基　　金：国家自然科学基金青年基金(52003165);辽宁省博士科研启动基金计划项目(2019-BS-190);辽宁省教育厅青年育苗项目(LQ2019005);辽宁省高等学校创新团队支持计划(LT2016013)。

摘　　要：针对氧化降解法制备的液体端羧基氟橡胶,创建硼氢化钠(NaBH_(4))/氯化镧(LaCl_(3))还原体系,对其羧基进行高效还原,转化为具有更高反应活性的羟基.采用红外光谱(FT-IR)、氢谱核磁(^(1)H-NMR)、氟谱核磁(^(19)F-NMR)、凝胶渗透色谱(GPC)和化学滴定法对原料和产物的分子链结构、数均分子量(M_(n))和官能团含量进行分析和表征,同时针对其反应机理、反应选择性进行研究.采用差示扫描量热法(DSC)和热失重分析(TGA)对其热力学性能进行测试,系统考察溶剂用量、反应温度、反应时间以及还原体系的比例对羧基转化率的影响.结果表明:在最佳反应条件下,以NaBH_(4)/LaCl_(3)为还原体系能够有效还原液体端羧基氟橡胶中的羧基,该反应较温和、反应选择性高、副反应少,产物的玻璃化转变温度(t_(g))为-25℃,热分解温度(t d)为241℃,羧基转化率可达85%.In order to convert the carboxyl groups of the carboxyl-terminated liquid fluoroelastomers that prepared by the oxidative degradation method into more reactive hydroxyl groups,a NaBH_(4)/LaCl_(3)reduction system was developed to efficiently reduce the carboxyl groups.Firstly,the structures,molecular weights and contents of end-groups of raw materials and products were analyzed and investigated by Fourier transform infrared(FT-IR),^(1)H nuclear magnetic resonance(^(1)H-NMR),^(19)F-NMR spectroscopy(^(19)F-NMR),gel permeation chromatography(GPC)and various chemical titration methods,respectively.Meanwhile the reaction mechanism and selectivity of NaBH_(4)/LaCl_(3)were studied.Secondly,the thermodynamic properties were investigated by differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA),the influence of the solvent,reaction temperature,reaction time and the ratio of reduction system on the conversion rate of carboxyl group were systematically investigated.The results showed that under the optimal reaction conditions,NaBH_(4)/LaCl_(3)system can effectively reduce the carboxyl groups.The reaction was mild,reaction selection was high,and the side reaction was less.The glass transition temperature(t_(g))of the product was-25℃,the thermal decomposition temperature(t d)was 241℃,and the conversion rate of carboxyl was about 85%.

关 键 词：氯化镧 还原 羟基 液体氟橡胶 

分 类 号：TQ333.93[化学工程—橡胶工业]