A series of crystalline shape memory polyurethanes (SMPUs) were synthesized from polycaprolactone diols and 4,4 -methylenedicyclohexyl diisocyanate (H 12 MDI) with chemical incorporation of allyl isocyanate modified graphene oxide (iGO) into the PU. Actuation of hybrid SMPUs by infrared (IR) absorption of iGO as well as the direct heat actuated SMPUs has been studied in terms of the isothermal crystallization rate, near-IR absorption, and thermal, mechanical, and shape memory properties. It was found that iGO functions as a multifunctional cross-linker at low contents and a nucleating agent at high contents, and as a reinforcing filler, while light absorption by the iGO induced melting of the PU soft segment, giving rise to a shape recovery of over 90% at 1% iGO (G10).

A freeze-gel casting method has been proposed to fabricate porous mullite-alumina composite with controlled 'designer' pore structure and improved compressive strength. In this work, a tertiary butyl alcohol-coal fly ash slurry system with appropriate addition of Al 2 O 3 was used. Unidirectional aligned macropore channels were developed by controlling the solidification direction of the tertiary butyl alcohol solvent. Simultaneously, microsized pores formed in the walls of the pore channels; consequently, the inner section of the walls of the pore channels exhibited a more porous structure than the outer walls. The compressive strength of the sintered porous composite increased as the porosity decreased, i.e. the low porosity gave a high compressive strength. After sintering at 1500uC with 40 wt-% solid loading, the mullite-alumina composite with a porosity of 61?2% exhibited a compressive strength of y64?3 MPa.

A series of interpenetrating polymer networks (IPNs) of vinyl-terminated polyurethane (VTPU) and poly(N-isopropylacrylamide) (PNIPAAm) was prepared by free radical polymerization. The effects of IPN composition and cross-linking density on the thermo-responsive and mechanical properties have been studied in terms of particle size, dynamic mechanical thermal properties, transmittance, swelling and de-swelling behavior and water transport mechanism. Results showed that the swelling ability of hydrogels increased over four orders of magnitude in terms of diffusivity, and phase transition became faster with increasing N-isopropylacrylamide (NIPAAm) content. Regarding the mechanical reinforcement of swollen gel, a significant increase in compression properties has been obtained by forming IPNs with polyurethane, which was tailor-made depending on the IPN composition and structure of polyurethane. Furthermore, a cross-linking density increase in the NIPAAm domain augmented rubbery modulus, decreased water swelling and increased water deswelling of the IPNs.

Polarized optical micrography (POM) images of gratings and UV–visible spectra of holographic polymer dispersed liquid crystals (HPDLC) are reported for a ternary monomer system composed of dipentaerythritol hydroxypentaacrylate/trimethylolpropanetriacrylate/N‐vinylpyrrolidone (DPHPA/TMPTA/NVP) = 7/2/1 by weight. Gratings were written by irradiation with an argon ion laser (λ = 488 nm) at various intensities (20–200 mW cm−2) on monomer/liquid crystal (LC) composite films of various compositions (75/25, 70/30, 65/35, 62/38, 60/40). Reflection efficiency–irradiation intensity–film composition relationships are obtained in three dimensional plots which show that maximum reflection moves from high LC content (38%) at low irradiation intensity (20 mW cm−2) to low LC content (25 wt%) at high irradiation intensity (200 mW cm−2). © 1999 Society of Chemical Industry