Dynamic behavior of glucose oxidase-containing microparticles of poly(ethylene glycol)-grafted cationic hydrogels in an environment of changing pH

Poly(diethylaminoethyl-g-ethylene glycol) microparticles were prepared by s uspension polymerization of diethylaminoethyl methacrylate, poly(ethylene g lycol) monomethacrylate and the crosslinking agent tetra(ethylene glycol) d imethacrylate in silicons oil using redox initiators. Particles of differen t sizes, crosslinking ratios and graft molecular weights were prepared. The changes in the swelling of the particles were studied as the pH was change d between 3.0 and 7.4. The particles showed rapid swelling/deswelling dynam ics in response to changes in pH. It was evident that faster response could be obtained from smaller particles. Changing the crosslinking ratio result ed in changes in the extent of swelling, as well as the speed of response. It was also found that longer graft lengths were responsible for increasing the effect of relaxation of the swelling of the network. (C) 2000 Elsevier Science Ltd. All rights reserved.