润物无声,启迪创新——从“冷冻聚合制备高分子量聚合物”综合实验谈起

Teaching and Learning of a Comprehensive Experiment on Synthesis of Ultrahigh Molecular Weight Polymers through Cryo-Polymerization

冷冻聚合是一种新发展的聚合反应实施方法,其聚合温度低于反应介质的凝固点,聚合场所为冻结聚合体系中的液相微区,液相微区的体积百分数约为10%。因为聚合温度低、液相微区的单体浓度很高,所以冷冻聚合是制备高/超高分子量聚合物的有效方法。本实验分别实施丙烯酰胺和丙烯酸的冷冻聚合,通过改变冷冻聚合条件调控聚合物的分子量,使用稀溶液黏度法测定所得聚合物的分子量。通过该实验,帮助学生理解自由基聚合分子量控制的基本原理,学会灵活运用Mayo方程,引导学生关注实验细节、掌握实验技巧、学会实验设计。

Cryo-polymerization is a newly developed polymerization technique.Its polymerization temperature is below the freezing point of the medium and the polymerization locus is indeed the liquid microphase(about 10%,volume percent)embedded in the frozen bulk.Due to the low polymerization temperature as well as the highly concentrated monomer in the polymerization locus,cryo-polymerization facilitates the preparation of(ultra)high molecular weight polymers.In this experiment,the cryo-polymerization of acrylamide and acrylic acid is performed separately,the molecular weight of the obtained polymer is modulated by varying polymerization parameters and determined by the dilute solution viscometry method.This experiment can prompt students to grasp the primary principle to control molecular weight of radical polymerization,utilize Mayo equation flexibility and learn some laboratory skills through watching out the experimental details,leading to acquisition of the ability to design experiment.