Fractionation of Poly(vinyl acetate) and the Phase Behavior of End-Group Modified Oligo(vinyl acetate)s in CO2
writer：Tan, B.; Bray, C. L.; Cooper, A. I.
keywords：ScCO2
source：期刊
specific source：Macromlecules
Issue time：2009年
Poly(vinyl acetate) (PVAc) is an inexpensive, high-tonnage bulk commodity polymer which, unlike most vinyl polymers, is moderately biodegradable. PVAc has been shown to exhibit anomalously high soly. in CO2 with respect to other vinyl hydrocarbon polymers. Understanding the phase behavior of PVAc in CO2 and its variation with structure is very important for its potential application as suitable surfactant, ligand, or phase transfer agent in a CO2 solvent process. In this article, PVAc has been fractionated using a supercrit. fluid extn. method (SCFE) to provide low mol. wt. fractions with narrow polydispersity. The phase behavior of hydroxyl terminated poly(vinyl acetate)s (PVAc-OH) were detd. by a high throughput gravimetric extn. (HTGE) screening method and a cloud-point pressure method using a variable vol. view cell (VVVC). The soly. of PVAc in CO2 strongly depends on the mol. wt. Oligomer PVAc-OH (Mw < 3000 gmol-1) is sol. in CO2 at low pressures but decreases in soly. with increasing mol. wt. End-group modification of oligomer PVAc-OH alters the phase behavior of the oligomers.