Aqueous core-shell particles based on polystyrene, poly(methyl methacrylate) or polycaprolactone have been formulated using a facile double emulsion-based solvent evaporation method. The size distribution is narrow, and the morphology control is remarkable given the simple characteristics of the encapsulation method. The inner droplets are stabilized by oil-soluble poly(ethylene oxide)-based block copolymers which are anchored in the polymeric shell by using hydrophobic blocks of the same type as that of the shell-forming polymer. This facilitates the efficient encapsulation of dyes and hydrophilic biocides. [Figure not available: see fulltext.].

Monolayers of asphaltene and resins on the water surface have been transferred at a surface pressure of 10 mN/m onto mica substrates using the Langmuir-Blodgett technique. Atomic force microscopy (AFM) has been used to examine the topography of these layers. Monolayers consisting of pure asphaltene fraction provide a rigid film with a close packed structure, while the resins build up a continuous open network. Mixed films of these two fractions, show that a gradually increase of resin concentration leads to an opening of the rigid asphaltene structure towards a more resin like configuration. Increased aggregation when the two heavy fractions are present in one film, is seen as larger individual units in the AFM-pictures. Addition of high molecular weight demulsifiers/inhibitors resulted in the same kind of influence on the asphaltene film as seen with the resins.

The effects of complex formation between sodium dodecylsulfate (SDS) and the positively charged (3-(2-methylpropionamide)propyl)trimethyl-ammonium chloride-acrylamide (MAPTAC-AM) copolymer have been studied in dilute and semidilute aqueous solution in the presence of 10 mM NaCl. Two different charge densities of the copolymer have been used in the study: 0.31 and 0.66, corresponding to the proportion of MAPTAC units. Dynamic light scattering (DLS) and rheometry (static low-shear and capillary viscometry) have been performed on the systems at different charge ratios, i.e., SDS/MAPTAC molar ratios, r. Regarding the phase behavior, the maximum binding ratio prior to precipitation differs between the copolymers. A 1.0% w/v solution of SDS/31% MAPTAC-AM is soluble at r = 0.4 , while an SDS/66% MAPTAC-AM solution of 1.0% w/v shows phase separation at this ratio. With excess surfactant, the complex in the former system is resolubilized at r=2.0, whereas the latter system is still phase-separated at r=5.0. DLS results show that, for both copolymers, the hydrodynamic radius, Rh, of the single-chain copolymer-surfactant complex decreases as a function of r, but then increases slightly prior to phase separation. The corresponding hydrodynamic virial coefficient, kD, changes in the same manner as Rh. The light-scattering data also show that the formation of larger structures is promoted as the polymer concentration is increased from 0.2 to 1.0% w/v. This is shown by the increase in the relative aggregate-to-single coil peak areas in the relaxation time distributions. Both systems have this common trend. The results from rheological measurements support the results from DLS. A reduction in intrinsic viscosity, [], is observed on increasing r up to phase separation. The major part of the static low-shear measurements showed Newtonian behavior for both systems at different copolymer concentrations (27.6-138 mM), and at different r. These systems, partially ionic polymer/oppositely charged surfactant, present very interesting rheological behavior at relatively high polymer concentrations and at low r values. Their behavior is similar to those of hydrophobically modified polyelectrolytes.

Shear induced aggregation of a Pectin stabilised emulsion trapped at the air-liquid interface was studied in a Couette system by video enhanced microscopy. From dimension analysis, Brownian motion was identified to enhance the probability of bond formation. The characteristic time scale of aggregation was found to scale as tc \sim / rather than tc \sim 1/˙ as expected for orthokinetic aggregation. The structure of very large clusters showed strongly rearranged strands and fractal scaling for low ˙ and , analysed by density auto-correlation. At high ˙ and , the cluster was dominated by larger drops and no fractal scaling could be determined for the accessible length scales.

Modifications of mineral surfaces were performed in order to gain insight into what surface properties are decisive of the accumulation of dental plaque. A non-charged, hydrophilic surface was made by two consecutive plasma polymerizations, firstly with allyl alcohol, secondly with acrylic acid, followed by adsorption of a poly(ethylene glycol)-poly(ethylene imine) adduct. A strongly hydrophobic surface was obtained by plasma polymerization of hexamethyldisiloxane. Ellipsometry was used to monitor protein interaction with the surfaces. The hydrophilic surface gave very little adsorption of both a model protein, IgG, and of saliva proteins. The hydrophobic surface, on the other hand, adsorbed high amounts of both types of proteins. In vitro adhesion of an oral bacterium, S. mutans, as well as in uivo studies, gave the opposite result, the hydrophobic surface giving less adhesion and less plaque accumulation than the hydrophilic surface. A tentative explanation of this behaviour is that the saliva proteins that bind to the hydrophobic surface adsorb in an unnatural conformation which does not favour bacteria adherence.

A variety of non-ionic reactive surfactants have been prepared from block copolymers precursors. These precursors are formed from a commercially available polyethylene glycol monoethylether as the hydrophilic sequence of the surfactant; this product is used as initiator of living polymerization of butylene oxide. Finally the reactive surfactants are obtained after proper functionalization of the precursors. The reactive surfactants are an inisurf with an asymmetric azo compound, a transurf with a thiol group, and a few surfmers with acrylic, methacrylic, styrenic and a-methylstyrenic reactive groups. These compounds have been engaged in styrene emulsion or dispersion polymerization. Several of them are useful to prepare stable latexes.

Enzymatic hydrolysis of a model triglyceride, palm oil, was carried out with lipase from Rhizopus sp. in microemulsions with varying water content. The microemulsions were based on a nonionic surfactant, pentaethylene glycol monododecyl ether (C12 EO5), buffered water solution and an oil component consisting of isooctane and palm oil at a weight ratio of 20:1. The structure of the microemulsions was characterized using Fourier transform pulsed-gradient spin-echo 1H NMR. The rate of reaction decreased as the water content of the reaction medium was increased. The self-diffusion coefficient of water, DW, was found to be constant within the interval 1-20% water. The difference in reactivity is believed to be due to a difference in structure of the palisade layer between water and hydrocarbon microdomains. The nonionic surfactant was demonstrated to be unsuitable for enzymatic reactions since only partial hydrolysis was obtained in all experiments. The surfactant, however, did not cause enzyme deactivation, even at very high concentrations.

Adsorption and covalent immobilization of Ig G to a grafted tetrabranched PEO/PPO block copolymer have been studied and related to the temperature-dependent properties of the grafted polymer. The investigation was performed by means of in situ ellipsometry, as well as by ESCA and ELISA measurements. The results show that the copolymer grafted to polystyrene (PS) surface contracts substantially upon increasing the temperature. A close interrelation was found between the properties of the grafted layer and the amount of protein (Ig G) that could be either adsorbed or covalently immobilized to the modified PS surface. By utilizing the reversed temperature phase behavior exhibited by these copolymers a relatively high loading of protein was obtained at temperatures close to the cloud point. By lowering the temperature after immobilization, the grafted layer regains its hydrophilicity and protein-rejecting properties. Thus, problems associated with interaction between bound protein and the underlying solid surface are minimized.