Spacer‐modified anion exchange resins were prepared by suspension copolymerization of ω‐bromoalkylstyrenes or ω‐bromoalkyloxymethylstyrenes with 2–8 mol % of divinylbenzene, followed by quaternization with trimethylamine. The thermal stability of the spacer‐modified anion exchangers of the OH form was examined by standing the resins in deionized water at 100–140°C for 30–90 days. The anion exchangers with alkylene chains such as butylene or heptylene groups between the benzene ring and the quaternary nitrogen exhibited higher thermal stability compared with commercial, strongly basic anion exchangers with benzylic ammonium groups. The thermal stability of the exchangers with butyleneoxymethylene or hexyleneoxymethylene spacers was also higher than that of the commercial exchangers. The exchanger with the propyleneoxymethylene spacer, however, had less stability than did the commercial ones. The decreased stability of this spacer‐modified exchanger is due to the accelerated degradation of the spacer chain via Hofmann elimination. The excellent stability of the anion exchangers with alkylene or alkyleneoxymethylene spacers, except propyleneoxymethylene, results from the structure of the exchangers, where there are no reactive benzylic carbons, which are attached directly to the quaternary nitrogen. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1161–1167, 1997

In this study, we prepared and characterized enzyme (α-chymotrypsin or lactase)-encapsulating core-shell fibermats by electrospinning. The hydrophilic copolymer of acrylamide (AM) and diacetone acrylamide (DAAM), poly(AM/DAAM), was used as the base material to obtain the core unit of nanofibers. During electrospinning, poly(AM/DAAM) was crosslinked with the bifunctional crosslinker adipic acid dihydrazide (ADH) in the presence of enzyme molecules. The cores were wrapped with hydrophobic poly(ε-caprolactone) (PCL) layers as shell unit. Different from the fibermats of only poly(AM/DAAM)/ADH, the core-shell fibermat of poly(AM/DAAM)/ADH and PCL exhibited sufficient mechanical strength and stability of the stacked nanofibrous structure in a neutral-pH buffer. Furthermore, when the PCL-shell thickness was controlled to be less than 150 nm, the encapsulated enzymes exhibited an apparent activity of >70–80% for low-molecular weight substrates in an immersion buffer. These results indicate that the core-shell fibermats of poly(AM/DAAM)/ADH and PCL (or other hydrophobic polymer) could be used as effective enzyme-immobilizing platforms.

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