| Abstract: | As a microcapsule with temperature sensitivity, poly(methacrylic acid)–polyethylenimine complex capsules containing N‐isopropylacrylamide units were designed. Two kinds of copolymers of methacrylic acid and N‐isopropylacrylamide were synthesized by free‐radical copolymerization. Partly crosslinked poly(methacrylic acid)–polyethylenimine complex capsules containing the methacrylic acid–N‐isopropylacrylamide copolymers were prepared at 40 or 25°C. The permeation of phenylethylene glycol through the capsule membranes was investigated. Permeability of the capsules prepared at 25°C increased monotonously with increasing temperature from 10 to 50°C. Permeability of the capsules prepared at 40°C also increased with increasing temperature up to 25°C but decreased above 30°C. Also, the degree of swelling of the membranes prepared at 40°C decreased above 30°C. Differential scanning calorimetry measurement showed that N‐isopropylacrylamide units underwent more efficient transition in the capsule membranes prepared at 40°C than in the membranes prepared at 25°C. The capsule membranes prepared at 40°C might have domains in which N‐isopropylacrylamide units are concentrated, whereas these units should distribute uniformly in the capsule membranes made at 25°C. Such a difference in distribution of N‐isopropylacrylamide units might result in the different permeation property of the capsule membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2703–2710, 2000 |
