A molecular recognition polymer membrane that uses a thermosensitive polymer with a host receptor has been developed. The membrane exhibits a high selectivity, in which β-cyclodextrin (CD) moieties recognize a specific guest molecule, and poly(N-isopropylacrylamide) [P(NIPAM)] controls the molecular recognition ability. A pendant CD monomer was introduced into the linear P(NIPAM) chain, and this resulted in a faster volume change from the increased diffusivity of water over the normal cross-linked gel. The copolymer was fixed onto the pore surface of a porous polyethylene substrate using plasma-graft polymerization. The temperature dependence of the binding constant of 8-anilino-1-naphthalenesulfonic acid ammonium salt showed a drastic decrease at temperatures above the lower critical solution temperature of the copolymer chains. The defining mechanism of the inclusion properties is the steric hindrance of the host-guest interaction, which depends on the thermosensitive volume change of the grafted chains. This membrane shows temperature-controlled molecular recognition and can be applied as a novel affinity separation system.

Agglomeration of particles in composite polymeric materials is a fundamental issue, but the relationship between the particle distribution and the composite mechanical properties is not fully understood. The ultimate goal of this study is to evaluate the effect of particle agglomeration upon mechanical properties of the composite. To achieve this goal, a colloidal crystalline array was encapsulated within a polymer matrix to make a model composite that has a well-ordered particle distribution. We characterized the particle distribution within the polymer matrix experimentally using Bragg diffraction of visible light and compared it with the interaction potential calculated by the Derjaguin–Landau–Verwey–Overbeek theory. Then, apparent cross-link densities of the composites were characterized from both swelling and mechanical measurements. Finally, the dynamic mechanical behavior of the composites with different particle distributions was analyzed. These data suggest that the particle distribution in the polymeric matrix plays an important role in the composite mechanical properties.

The viscoelastic properties of nanocomposites are influenced by both the nanoparticle distribution and the nanoparticle-polymer affinity. These two parameters are closely coupled, and evaluation of individual contributions to the mechanical properties is a critical requirement for efficient development of nanocomposites.To decouple these two effects, we utilized charge repulsion among nanoparticles so that we could essentially eliminate particle agglomeration. We then investigated how the nanoparticle-polymer affinity relates to the mechanical properties of the nanocomposite by comparing silica and polystyrene nanoparticles. The surface roughness of the particles and the molecular conformation of the interfacial layer between the polymer and the nanoparticles were characterized by synchrotron small-angle X-ray scattering and quartz crystal microbalance, respectively. On polystyrene particles, the surface roughness was larger, and the polymer adsorbed strongly. Consequently, the mobility of the adsorbed polymer was reduced compared to that on silica particles. This reduced mobility explains a smaller viscoelastic loss for the polystyrene-filled nanocomposite compared to the silicafilled nanocomposite.