Stephen Rimmer

Fluorescence spectroscopy on a series of aqueous solutions of poly(acrylic acid) containing a luminescent label showed that polymers with molar mass, Mn < 16.5 kDa did not exhibit a pH responsive conformational change, which is typical of higher molar mass poly(acrylic acid). Below this molar mass, polymers remained in an extended conformation, regardless of pH. Above this molar mass, a pH-dependent conformational change was observed. Diffusion-ordered nuclear magnetic resonance spectroscopy confirmed that low molar mass polymers did not undergo a conformational transition, although large molar mass polymers did exhibit pH-dependent diffusion.

This paper is a survey of the role and impact of competitive tendering and contracting (CTC) policies in the public sector. The paper examines the theoretical rationale for introducing competition in the provision of public services and the methodology by which contracting decisions are reached. It investigates the extent of implementation and nature of outcomes in several countries. A broad sweep of the empirical findings suggests that CTC generates substantial cost savings. Lack of adequate data makes an assessment of the effect on quality more troublesome, and further research is needed

Highly branched poly(N-isopropylacrylamide) (PNIPAM) compounds were prepared by copolymerization of 3H-imidazole-4-carbodithioic acid 4-vinylbenzyl ester, 1, with N-isopropylacrylamide (NIPAM) using reversible addition−fragmentation chain transfer (RAFT) polymerization. The polymerizations proceeded well with few side reactions. An increase in the content of 1 in the monomer feed appears to increase the number of branch chains, and at the same time no evidence was obtained for the presence of substituted acrylamide chain ends that may potentially result via elimination of the dithioate group. The polymer products show a clear tendency to increased molecular weight as the extent of conversion of monomer increases, while size exclusion chromatography (SEC) profiles indicate a complex distribution of molecular weights compared to linear polymers obtained with a non-RAFT carboxylate monomer. Both NMR and viscometry indicate that, as expected, increasing the amount of 1 in the feed has the effect of increasing the degree of branching in the final product. This increase in branching reduces the intrinsic viscosity of the solutions of the highly branched polymers compared to similar linear polymers. Poly(N-isopropylacrylamide) displays a lower critical solution temperature (LCST) in aqueous solutions, and cloud point data indicate a clear effect of chain architecture on the temperature at which this transition occurs. Thus, a set of linear analogous copolymers have LCST's that, for equivalent mole fractions of imidazole content, are higher than the similar highly branched polymers. However, on complexation of copper by the imidazole groups the LCSTs of the linear and highly branched sets cannot be differentiated.

Abstract Core–shell molecularly imprinted polymers (CS‐MIPs) have been prepared by aqueous emulsion polymerization using water‐soluble template molecules. An amphiphilic binding monomer, oleyl phenyl hydrogen phosphate and ethylene glycol dimethacrylate were used in the formation of highly crosslinked surfaces around divinyl benzene crosslinked polystyrene core colloids. Evidence was obtained by transmission electron microscopy (TEM) for a change in surface morphology when the polymer shell was formed in the presence of a template. The caffeine‐imprinted polymers were shown to bind caffeine in preference to theophylline from an equimolar mixture of the compounds in aqueous solution at pH 7.0, whilst concentration–binding (Scatchard) curves revealed the presence of two populations of binding sites in aqueous phosphate buffer at pH 8.0 for caffeine and theophylline. Similar studies were also carried out for ( S )‐propranolol and ( S )‐atenolol at pH 5.5, which also revealed the presence of two populations of binding sites for core–shell particles imprinted with these compounds. ( S )‐Propranolol was selectively removed from a solution of ( S )‐propranolol and ( S )‐atenolol by both of the CS‐MIPs, whereas the non‐imprinted particle showed no selectivity for either component.