The time evolution of void structures in highly purified polymer latex dispersions was studied with a confocal laser scanning microscope. In such dispersions, which were initially homogeneous, the voids grew with time when the dispersions were kept standing and formed more quickly in the internal material than in material close to the glass-dispersion interface. Void formation is thus not an artifact arising from the presence of the interface. A similar structural inhomogeneity, in apparently homogeneous systems, is discussed for simple ionic solutions, ionic polymer solutions, and Langmuir-Blodgett films.

By fixing charged colloidal crystals in a poly(acrylamide) hydrogel matrix, we fabricated photonic crystals whose diffraction peak wavelengths were tunable by applying mechanical stress. The reflection spectrum for a single crystal grain was measured by applying microspectroscopy under compression. The photonic band gap wavelength shifted linearly and reversibly over almost the entire visible light wavelength region (460-810 nm).

Amino-group-containing j3-cyclodextrin (B-CD) was modified with poly(N-isopropylacrylamide) (PIPA, M, = 4000) chains. The inclusion of 8-anilino-1-naphthalenesulfonic acid (ANS) into the cavity of the modified cyclodextrin was largely affected by the temperature due to the coil-globule transition of PIPA chains introduced to the ,8-CD molecule. The importance of cooperative binding of ANS by the PIPA chains and the cavity of B-CD was suggested.Molecular recognition phenomena have been of interest in recent years.l Complexations of small organic compounds with polymeric compounds are very useful to construct artificial host-guest systems. These systems have been examined to mimic biological recognition, which are related to enzyme catalyses, transfer of genetic information, and transportation of information on surfaces of cell membranes.In this paper we examined the construction of a molecular recognition system controlled by external stimuli. We chose cyclodextrin (CD) as a host, because of its capability to include diverse compounds into its apolar ~a v i t y .~-~ We introduced poly(N-isopropylacrylamide) (PIPA) chains into primary OH groups of CD and then examined the effect of the presence of PIPA chains in the inclusion phenomena by CD molecules.