Corporate R&D, LG Chem Research Park , 104-1, Moonji-dong, Yuseung-gu, Daejeon, 305-380, Republic of Korea.
Department of Biosystems & Biotechnology, Division of Biotechnology, Korea University , Seoul, 136-713, Republic of Korea.
Anal Chem. 2016 Feb 2;88(3):1516-20. doi: 10.1021/acs.analchem.5b04357. Epub 2016 Jan 8.
The crystallinity of polyethylene, which significantly affects the properties of the polymer, is quite sensitive to the concentration of its branches. Thus, it is necessary to estimate branch concentration with reasonable accuracy. Currently, (13)C NMR and gel permeation chromatography-Fourier transform infrared spectroscopy are widely-used analysis methods for the analysis of branch concentration. Despite several advantages, these methods sometimes have limitations. For instance, the preparation of samples for (13)C- NMR is tedious because high-concentration samples are required and the time for analysis is greater than 12 h. To more efficiently estimate the branch concentration of polyethylene, we developed a new high-field (1)H NMR method with an improved peak resolution by employing (1) homonuclear decoupling and (2) 2D heteronuclear correlation. The new method was observed to significantly reduce the experimental time to ∼ 30 min; furthermore, sample preparation was relatively simple because the method did not require high-concentration samples.
聚乙烯的结晶度对聚合物的性能有很大影响，而其支化度对结晶度非常敏感。因此，有必要以合理的精度估计支化浓度。目前，（13）C NMR 和凝胶渗透色谱-傅里叶变换红外光谱是分析支化浓度的常用分析方法。尽管这些方法有几个优点，但有时也存在局限性。例如，（13）C-NMR 分析的样品制备繁琐，因为需要高浓度的样品，而且分析时间大于 12 小时。为了更有效地估计聚乙烯的支化浓度，我们开发了一种新的高场（1）H NMR 方法，通过采用（1）同核去耦和（2）2D 异核相关，提高了峰分辨率。新方法的实验时间显著缩短至约 30 分钟；此外，由于该方法不需要高浓度的样品，因此样品制备相对简单。
