傅立叶变换红外光谱技术在超临界CO2作用聚合物体系中的应用

超临界CO₂（scCO₂）作为一种物理化学性质优良、具有高扩散速率及优良溶解性能的溶剂，在科学研究及工业生产中广受青睐。将scCO₂应用于聚合物体系中，CO₂ 与聚合物间特殊的相互作用有利于CO₂分子在聚合物中的吸附与扩散。同时通过CO₂的吸附及其对聚合物的溶胀和塑化作用，聚合物所处微观化学环境以及整体结构性质会发生一定的变化。由于傅立叶变换红外光谱（FTIR）技术能够有效地考察化学环境变化对分子结构造成的影响，这一表征技术在超临界CO₂作用体系中广为应用。本文主要选取了近年来利用FTIR技术考察scCO₂作用于聚合物体系的一些实例，从CO₂-聚合物相互作用机理，scCO₂对聚合物或生物大分子的加工过程的影响两方面，阐述了利用红外光谱技术在scCO₂作用体系中的应用以及前景。

Application of FTIR Spectroscopy in Polymereric Systems under Supercritical CO2 Processing

Supercritical carbon dioxide (scCO₂) is recognized as an outstanding solvent in polymer processing and scientific investigation, arising from its remarkable intrinsic traits such as high diffusivity and excellent solubility. Once applied into polymer processing, the interactions between CO₂ and polymers may assist the sorption and diffusion of CO₂ in polymer chains, which may perturb the chemical environment of the molecular structure with the penetrating of CO₂ molecules, and can be probed by Fourier transform infrared (FTIR) spectroscopy. Besides, scCO₂ may improve the mechanical properties of the material, ascribing to the CO₂ sorption, the CO₂-induced plasticization and the swelling of polymers. FTIR spectroscopy is also proved to be an effective tool in investigating on the structure information, especially of proteins or semicrystalline polymers. In this review, some researches in this field are discussed, in order to illuminate the handling of FTIR in studying the interaction between scCO₂ and polymers and revealing the rearrangements of polymer chain at molecular level. Then the promising application of this method in scCO₂ induced polymeric materials systems is clarified and prospected.Contents
1 Introduction
2 Study of the interaction between CO₂ and polymers by FTIR
2.1 On the Lewis acid-base interaction
2.2 On the hydrogen bonding in scCO₂
3 Study of the polymer processing in scCO₂ by FTIR
3.1 On the sorption of CO₂ in polymers by ATR-IR
3.2 On the scCO₂ induced crystallization of semicrystall polymers
3.3 On the conformational change of proteins in scCO₂
4 Conclusion