Abstract. Waterborne polyurethane-acrylic hybrid nanoparticles for application as pressuresensitive adhesives (PSAs) were prepared by a one-step miniemulsion polymerization. The addition of polyurethane into a standard waterborne acrylic formulation results in a large increase of the cohesive strength and hence a much higher shear holding time (greater than seven weeks at room temperature), which is a highly desirable characteristic for PSAs. However, with the increase in cohesion, there is a decrease in the relative viscous component, and hence there is a decrease in the tack energy. The presence of a small concentration of methyl methacrylate (MMA) in the acrylic copolymer led to phase separation within the particles and created a hemispherical morphology. The tack energy was particularly low in the hybrid containing MMA because of the effects of lower energy dissipation and greater crosslinking. These results highlight the great sensitivity of the * Corresponding author. E-mail: j.keddie@surrey.ac.uk. Tel +44-1483-686803; Fax +44-1483- 686781.Published in Langmuir (2011) 27(7) pp 3878-3888 2 viscoelastic and adhesive properties to the details of the polymer network architecture and hence to the precise composition and synthesis conditions.

Urethane/acrylic hybrid latex particles are prepared by miniemulsion polymerization for an application as soft adhesives. The polymerization of the acrylic monomers and grafting of an isocyanate functionalized PU on a hydroxyl functionalized monomer (HEMA) take place simultaneously, resulting in a complex PU/acrylic network while avoiding any macroscopic phase separation. Its structure can be tuned by changing the extent of grafting and a specific model is applied to analyze the final polymer microstructure. The resulting materials have a low level of adhesion but display an exceptionally high resistance to shear. Two parameters are varied: the fraction of HEMA in the monomer composition and the diol concentration.

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The effects of the CTA concentration on polymerization kinetics, polymer microstructure, particle morphology, and adhesive performance of waterborne hybrid PSAs prepared by simultaneous free‐radical and addition miniemulsion polymerizations are studied. The development of the microstructure is shown to differ from waterborne acrylic PSAs obtained by free‐radical polymerization because of the contribution of the addition reaction, which in turn causes marked differences in the adhesive performance of the final films. A computer simulation is developed to obtain detailed information about the microstructure of PU/acrylic hybrids and to correlate the microstructure with the final adhesive properties.magnified image

Miniemulsion polymerization is particularly well suited to synthesize hybrid nanocomposites. The first stage in this process is to prepare hybrid monomer-resin nanodroplets by miniemulsification. In this work, the efficiencies of several homogenization equipment (rotor-stator, sonicator, and high-pressure homogenizer) were compared. For the most efficient one, the effect of homogenization conditions, type of resin, emulsifier concentration, and viscosity of the organic phase on the size of the composite droplets was investigated. The results agreed well with a two-step mechanism in series involving droplet breakup and coalescence.

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A computer simulation is presented for the prediction of the detailed microstructure of acrylic‐polyurethane hybrid polymers synthesized by miniemulsion polymerization. The simulation considers the polymerization of a mixture of acrylic monomers, one of them having a hydroxyl group, in the presence of a diisocyanate terminated prepolymer and a diol. The simulation approach is able to reproduce the experimental tendency (gel content, sol molecular weight and swelling capability) and provide additional information that is not attainable otherwise, as the distribution of pendant PU chains and dangling acrylic chains and the loop size distribution of the hybrid network. The analysis of such complex structures opens the possibility of tuning the performance of crosslinked emulsion polymers by adjusting their microstructure.

Band structure of polymer extracted from oligomer calculations by elongation method and its applications to nanosystems AIP Conf.Abstract. Molecularly Imprinted Polymers (MIPs) for the selective recognition properties of curcumin (CUR), a cancer chemopreventive agent were obtained by a non-covalent imprinting approach with bisdemetoxycurcumin (BDMC) as the template molecule. The double bond of BDMC has been reduced in order not to be involved in polymerization and make the template molecules easy to be eluted. Several functional monomers have been evaluated to maximize the interactions with the template molecule during polymerization. MIPs prepared by bulk of N-(2-aminoethyl) metacrylamid hydrochlorideas functional monomer, ethylene glycol dimethacrylate as crosslinker, 2,2'-azobis (2'4-dimethyl valeronitril) as initiator and acetonitrile as porogen. Non-imprinted polymer (NIP) have been also synthesized for reference purposes. UV-vis spectroscopy has been used to predict the template to functional monomer ratio which indicates the formation of 2:1 complexes between monomer and curcumin and the association constants (K 11 = 2529 μM and K 12 = 1960.75 μM in acetonitrile). The capacity and imprinting factor have been evaluated as stationary phases in high-pressure liquid chromatography to CUR and BDMC. The binding properties and the homogeneity of the binding sites of the different polymers have been studied by Freundlich isotherm modeling and weight average affinity and number of binding sites. One of the foremost applications of molecular imprinting has been in molecularly imprinted solid phase extraction and it has the ability to separate and preconcentrate between closely related compounds in curcuminoids.