Polyisocyanate based aerogels combine ultralow thermal conductivities with better mechanical properties than silica aerogel, but these properties critically depend on the nature of the gelation solvent, perhaps more so than on any other parameter. Here, we present a systematic study of the relationship between the polyurethane-polyisocyanurate (PUR-PIR) aerogel microstructure, surface area, thermal conductivity, and density and the gelation solvent's Hansen solubility parameters for an industrially relevant PUR-PIR rigid foam formulation. We first investigated aerogels prepared in acetone-dimethyl sulfoxide (DMSO) blends and observed a minimum in thermal conductivity (λ) and maximum in specific surface area for an acetone:DMSO ratio of 85:15 v/v. We then prepared PUR-PIR aerogels in 32 different solvent blends, divided into three series with δ, δ, and δ fixed at 15.94, 11.30, and 7.48 MPa, respectively, corresponding to the optimum parameters for the acetone:DMSO series. The aerogel properties display distinct dependencies on the various solubility parameters: aerogels with low thermal conductivity can be synthesized in solvents with a high δ parameter (above 7.2) and δ around 16.3 MPa. In contrast, the δ parameter is of lesser importance. Our study highlights the importance of the gelation solvent, clarifies the influence of the different solvent properties, and provides a methodology for a targeted search across the solvent chemical space based on the Hansen solubility parameters.

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The inhibition of protein adsorption to the surfaces of biomedical devices is a crucial requirement for avoiding implant‐associated infections or thrombus formation on blood‐contacting artificial surfaces and thus for increasing the long‐term biocompatibility of the devices. Here, the use of surface plasmon resonance and scanning force microscopy using protein‐modified tips (see figure) to study protein adhesion on poly(ethylene glycol) (PEG) grafted polymer materials is discussed. The PEG‐rafted materials are revealed to have significantly reduced affinity to proteins.

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Hydrogels have become increasingly important in the biomedical field. The aim of this study was to develop amphiphilic poly(ethylene glycol) grafted polymethacrylates with curable side groups. The water‐soluble polymers were synthesised by free‐radical copolymerisation of methyl methacrylate, α‐methyl‐ω‐methacroyl‐poly(ethylene glycol) and 2‐hydroxyethyl methacrylate (HEMA). The methacrylate containing hydrogel precursors were obtained by reacting the free hydroxyl groups of HEMA in the polymer with methacrylic anhydride in the presence of catalyst. γ‐Irradiation has been used as an elegant method for crosslinking and simultaneous sterilisation. The influence of the irradiation dose (5, 15, 25 kGy) on the polymers was examined by the determination of the gel and sol fraction. In an aqueous environment these materials behave as hydrogels with more swelling at lower temperatures. Since the coatings can be applied in mild conditions, eg water, these materials are looking very promising as thin film coatings for biomedical applications. Copyright © 2003 Society of Chemical Industry