摘要
将原位全反射傅立叶红外光谱（in situATR-FTIR）技术应用于研究稀土催化丁二烯配位聚合反应过程,探讨了采集FTIR谱图的背景、用于定量计算的特征峰的选择与确定、单体浓度和所确定的特征峰强度的关系及丁二烯溶液聚合反应动力学.在聚合过程中不同时间取样得到聚合物样品,采用GPC、FTIR、POM和DSC分别对这些样品进行分子量及其分布、微观结构及其含量、玻璃化温度及结晶特性的分析与表征.结果表明,选用溶剂正己烷为背景,采集的FTIR谱图（600-1800 cm^-1）中仅出现丁二烯的3个特征峰1592、1010和904 cm^-1,且基线更为平滑,计算误差小.在丁二烯浓度为0.46-3.88 mol.L^-1的范围内,丁二烯的这3个特征峰的强度均与丁二烯浓度成正比,其中904 cm^-1处的特征峰强,可选作定量计算的特征峰.聚合反应速率对单体浓度呈现一级动力学关系,表观增长活化能为56.5 kJ.moL^-1.聚丁二烯产物的分子量随单体转化率呈线性增加,其GPC谱图表明所得聚合物的分子量呈单峰分布,分布指数（Mw/Mn）在2.5左右.聚丁二烯产物中顺-1,4结构含量大于98%,其玻璃化转变温度约为-109℃,可产生较明显的结晶现象.
FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance（ATR） immersion probe was utilized to study in situ coordination polymerization of butadiene（Bd） in hexane（HEX） with Neodymium-based catalyst.The relationship of their intensity at signal bands of Bd and its concentration were investigated.The kinetic studies of polymerization of Bd were conducted by in situ ATR-FTIR.The signal band at 1592 cm^-1 was assigned to the stretching vibration of Bd,and the signal bands at 1010 cm^-1 and 904 cm^-1 were assigned to the deformation vibration of Bd.The Bd/HEX solution exhibited only the above three signal bands of Bd in the FTIR spectrum,and solvent interference was negligible when HEX spectrum was chosen as the background.All the intensity at the signal bands of 1592,1010 and 904 cm^-1 were found to be proportional to the Bd concentration in the range of 0.46～3.88 mol·L^-1.The stronger signal band at 904 cm^-1 was chosen to monitor the Bd concentration during polymerization,and the Bd conversion was calculated on the basis of the linearity dependence of Bd concentration on the corresponding peak intensity at 904 cm^-1.The agreement between the FTIR and conventional（gravimetric） kinetic data is excellent in all four sets of experiments.It is evident that signal band at 904 cm^-1 can be used for the convenient real-time monitoring of Bd polymerization.The first-order plots were linear at different polymerizations and thus polymerization rate was first order with respect to monomer concentration.The polymerization rate increased with increasing polymerization temperature,and the apparent propagation activation energy was determined to be 56.5 kJ·moL^-1.The GPC traces of polybutadiene products obtained at different polymerization temperatures exhibited relatively narrow unimodal molecular weight distribution,and polydispersity index（Mw/Mn） was around 2.5.The molecular weight of resultant polymers increased linearly with monomer conversion.The polybutadienes with high cis-1,4 configuration ranging from 98.0% to 99.2% and low vinyl configuration of around 0.4% could be prepared with Neodymium-based catalyst,leading to low Tg and some crystal line formation observed in DSC and POM analysis.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2010年第2期211-216,共6页
Acta Polymerica Sinica
基金
国家高技术研究发展计划(863计划
项目号2006AA03Z552)
国家自然科学基金(基金号20204001
50903003)
中国石化股份公司项目
教育部长江学者和创新团队发展计划(项目号IRT0706)资助
