BENDING OF BI-GELS

The bending of bi-gels has been studied as a function of temperature, acetone concentration, and NaCl concentration. The bi-gels consist of acrylamide on one side, and the interpenetrating polymer networks of a crylamide and N-isopropylacrylamide on the other side. The maximum ben ding strain achieved by the bi-gel is about 0.85. The bending mechanis m of the bi-gels reported here is due to the engineered structure hete rogeneity, in contrast with previous homogeneous gel bending which is induced by external gradient fields. The kinetic behavior of the bi-ge l is discussed. A theoretical model is used to estimate the collective diffusion coefficient D-c of the IPN side of the bi-gels in pure wate r and in salt solution. The results agree with those obtained by the l ight-scattering method. (C) 1996 American Institute of Physics.