ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Solvent dependent swelling behaviour of poly(N-vinylcaprolactam) and poly(N-vinylcaprolactam-co-itaconic acid) gels and determination of solubility parameters

Selva Çavuş, Elçin Çakal, and Lutfullah M. Sevgili

Department of Chemical Engineering, Faculty of Engineering, Istanbul University, Avcilar, 34320, Istanbul, Turkey

E-mail: selva@istanbul.edu.tr

Abstract: Swelling behaviour of poly(N-vinylcaprolactam) (PVC) and poly(N-vinylcaprolactam-co-itaconic acid) (P(VC-co-IA)) gels was investigated in different solvents (water, ethanol, methanol, isopropyl alcohol (IPA), chloroform, toluene, acetone) and in binary solvent mixtures (ethanol/chloroform, ethanol/methanol, IPA/chloroform, ethanol/water, IPA/water). Gels were synthesised in ethanol by the free radical cross-linking polymerisation method at 60°C for 24 h in the presence of azobis( isobutyronitrile) and allyl methacrylate as the initiator and cross-linker, respectively. And also, ethanol/distilled water mixture (φ_r = 4 : 1) was used as the synthesis medium to determine its effect on the swelling of gels. It was found that the presence of water in the synthesis medium significantly affected the equilibrium swelling value (ESV) and the swelling tendency of gels both in solvents and in solvent mixtures. All gels synthesised in ethanol showed the highest swelling in chloroform. The gels synthesised in the ethanol/water mixture displayed different swelling behaviour. In this case, while chloroform was still valid for maximum swelling of PVC, P(VC-co-IA) had the highest swelling in methanol. Solubility parameters of gels were predicted by the van Krevelen-Hoftyzer (VKH) and Hoy methods (group contribution methods) and theoretical calculations verified the experimental swelling order.

Keywords: solubility parameter – group contribution methods – swelling behaviour – N-vinylcaprolactam – itaconic acid

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0153

Chemical Papers 69 (10) 1367–1377 (2015)