Mobility of Spin Probes in Quaternized Poly(4-vinylpyridine) Membranes

Abstract

ABSTRACT:The mobility of nonionic and anionic spin probes in water-containing quaternized poly(4-vinylpyridine) membranes was investigated by means of an electron spin resonance (ESR) technique. Poly(4-vinylpyridine) was quaternized and crosslinked by dibromoalkane Br(CH2).Br (n = 4, 6, 8, I 0), and the effects of the side alkyl chain length were studied. Three spin probes, 2,2,4,4-tetramethyl-1,2,3,4-tetrahydro-y-carboline-3-oxyl (SPII), 2,2,6,6-tetramethyl-lpiperidinyloxy (SPIV), and sodium 2,2,5,5-tetramethyl-l-pyrrolidinyloxy-3-carboxylate (ASP!), were used. In the temperature region examined, the side methylene chain length had no effect on the mobility of SPII and SPIV, but a little effect for ASPI. This suggests that the ASP! can monitor the mobility of the side alkyl chain. In addition, the effects of water on the mobility of the spin probes were investigated. The mobility of the spin probes was much greater in the membrane containing 30 wt% water than in that containing 3 wt% water, and the polarity around the probes was larger in the former than in the latter membrane. From this, as pointed out in our previous papers on nylon 6/spin probe systems, the effects of water are divided into (!) the effects on the mobilities of the polymer chains and probe molecules, and (2) the effects on the microenvironment around the spin probes. KEY WORDSSpin Probe / Nitroxide / Poly(4-vinylpyridine) / Molecular Motion / Water/ ESR / In the study of membrane transport phenomena, knowledge on the states of penetrants in membranes gives a clue to the mechanism of the transport involved. From this point of view, we investigated the mobilities of spin probes in nylon films by means of an electron spin resonance (ESR) technique. 1 -5 As a results, their mobilities increased with increasing methylene chain length of the nylon, and were strongly affected by water.measurements. P4VP has a high chemical reactivity which is due to its nucleophilic and weakly basic ring nitrogens. This reactivity makes it very attractive a material for a number of applications. 6 Recently quaternized P4VP membranes were applied to charged reverse osmosis membranes, and the dependence of the hydrodynamic permeability and the salt rejection on the charge density of the membrane was investigated. 7 In the present study, poly(4-vinylpyridine) (P4VP) membranes were prepared by quaternizing and crosslinking with dibromoalkane Br(CH 2 )"Br (n = 4,6,8,10), and the mobility of nonionic and anionic spin probes in these membranes was studied by means of ESR We focus our attention on the effects of the side methylene chain length and water on the mobility of the spin probes in the quaternized P4VP membranes. The effects of the side chain length on the mobility of 4-hydroxy-2,2,6,6-tetramethyl-l-piperidinyloxy in a series of * Present address:

Self-organization of poly(allylamine)s containing hydrophobic groups and its effect on the interaction with small molecules. 1. Static fluorometry

“…Compact intramolecular micelle formation has been proved by viscosity,19 light scattering,20 and surface tension. 21 In our previous work on the mechanism of interaction between dyes and polysoaps22 and the mobility of spin probes in a polysoap solution, 23 it was found that the microenvironment of the polysoap is much more rigid and hydrophobic than that of low molecular surfactant micelles. The strongly hydrophobic microdomain formed by polysoaps is known to serve as a reaction field to accelerate hydrolysis and decarboxylation reactions.…”