Noda Isao, Allen William M, Lindberg Seth E
The Procter & Gamble Company, 8566 Beckett Road, West Chester, Ohio 45069, USA.
Appl Spectrosc. 2009 Feb;63(2):224-32. doi: 10.1366/000370209787392012.
The emulsion copolymerization of styrene and 1,3-butadiene using an oligomeric nonionic surfactant as an emulsifier to make a styrene-butadiene rubber (SBR) copolymer latex was monitored by real-time in situ Raman spectroscopy. Time-resolved Raman spectra collected during the early stage of the polymerization reaction were subjected to a series of data analysis techniques, including two-dimensional (2D) correlation spectroscopy, multivariate self-modeling curve resolution (SMCR), and kernel analysis, to elucidate the fine details of the complex reaction process. Generalized 2D correlation analysis of time-resolved Raman spectra readily identified the characteristic Raman scattering bands for the monomers and copolymer. Cross-peaks appearing in 2D Raman correlation spectra showed that the decrease in the spectral intensity of Raman bands assignable to 1,3-butadiene occurs before the band intensity changes for styrene or SBR copolymer. The positions of asynchronous cross-peaks were used to identify a spectral region with the most distinct pattern of intensity variations, which in turn could be used as the starting point for the alternating least squares iteration of the SMCR analysis. SMCR analysis of the time-resolved Raman spectra generated a set of estimated pure component spectra and concentration profiles of styrene, 1,3-butadiene, and SBR copolymer without requiring independently measured calibration data. The estimated concentration profiles of monomers and copolymer indicated that the reaction of 1,3-butadiene started before the consumption of styrene and production of SBR copolymer. Kernel analysis of the estimated concentration profiles provided a succinct measure of the similarity and dissimilarity of the concentration changes of monomers and copolymer.
采用一种低聚非离子表面活性剂作为乳化剂，通过实时原位拉曼光谱监测苯乙烯和1,3 - 丁二烯的乳液共聚合反应，以制备丁苯橡胶（SBR）共聚物胶乳。在聚合反应早期收集的时间分辨拉曼光谱经过一系列数据分析技术处理，包括二维（2D）相关光谱、多元自建模曲线分辨（SMCR）和核分析，以阐明复杂反应过程的详细信息。对时间分辨拉曼光谱进行广义二维相关分析，很容易识别出单体和共聚物的特征拉曼散射带。二维拉曼相关光谱中出现的交叉峰表明，归属于1,3 - 丁二烯的拉曼带的光谱强度下降发生在苯乙烯或SBR共聚物的谱带强度变化之前。异步交叉峰的位置用于识别强度变化模式最明显的光谱区域，这反过来又可作为SMCR分析交替最小二乘迭代的起点。对时间分辨拉曼光谱进行SMCR分析，生成了一组估计的纯组分光谱以及苯乙烯、1,3 - 丁二烯和SBR共聚物的浓度分布，而无需独立测量的校准数据。单体和共聚物的估计浓度分布表明，1,3 - 丁二烯的反应在苯乙烯消耗和SBR共聚物生成之前就已开始。对估计浓度分布进行核分析，提供了一种简洁的方法来衡量单体和共聚物浓度变化的相似性和差异性。
