SEEDED COPOLYMERISATION

Temperature-sensitive micron-sized monodispersed composite polymer particles were prepared by seeded copolymerisation of dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate with 1.77 micrometresized monodispersed PS seed particles. The change in surface properties at temperatures above and below 35C was examined by DSC, trypsin activity and the adsorption/ desorption behaviours of low molecular weight cationic emulsifier as well as biomolecules. From the results, it is concluded that the micron sized monodispersed PS/ poly(dimethylaminoethyl methacrylate-co-ethylene glycol dimethacrylate) composite particles can be expected to be a temperature-sensitive carrier for biomolecules. Potential in chromatographic applications is suggested. 20 refs. 

Seeded copolymerisation of monodisperse particles with composition y... 

Surfmers , i.e. surfactants which also acted as copolymerisable monomers, were synthesised from the hemi-ester of a fatty alcohol and maleic anhydride and were then used in the preparation of self-crosslinking dispersions by seeded semi-continuous emulsion polymerisation of acrylate monomers. Water-borne exterior wood stains were prepared from the dispersions and their properties were studied. The use of surfmers as sole emulsifiers in emulsion polymerisation was considered and data were obtained on the effects of surfmers on film formation, water barrier properties, gloss retention and mechanical properties. Environmental aspects of the use of products involving surfmers were examined. 6 refs. 

A multistep emulsion polymerisation technique was used to produce cationic latex particles with surface amino groups. Seed particles of polystyrene were copolymerised with aminoethyl methacrylate hydrochloride or vinyl... 

Polyurethane acrylate (PU-A) containing a double bond and COOH group was synthesised by the stepwise reaction of TDI, polyetherdiol, dimethylolpropionic acid (DMPA) and 2-hydroxypropyl acrylate (HPA). The PU-A was neutralised with triethylamine and self-emulsified in water to form the PU-A emulsion seed. The seeded emulsion copolymerisation of methyl methacrylate (MMA) onto the PU-A seed was carried out at 80C under soap-free conditions and an anionic latex of P(UA-MMA) was obtained. The structure of the P(UA-MMA) copolymer, its latex properties and the cast film were significantly affected by the amounts of HPA, DMPA and MMA. The results were discussed. 21 refs. 

Details are given of the preparation of model ethyl acrylate-methacrylic acid copolymer latices by non-seeded semicontinuous emulsion copolymerisation. Polydispersity was examined using dynamic and static light scattering. Correlations between hydrodynamic volume and viscosity properties of the dispersions are discussed. The different character of the particle structure was confirmed by differences in particle disintegration after alkali addition or in the presence of methanol. 19 refs. 

Polymerisable styrenic surfactants (surfmers) and non-reactive analogues were applied in emulsion copolymerisation of acrylic monomers in a seeded semi-... 

A series of multi-hollow structure core-shell latex particles in the presence and absence of acrylic acid was synthesised by seeded emulsion copolymerisation, then... 

Methyl methacrylate-butyl acrylate copolymer latex particles were synthesised by both seeded and unseeded semicontinuous emulsion copolymerisation. Particle size and surface charge densities were characterised by TEM and potentiometric and conductimetric titrations. An investigation of the effect of surface density on zeta-potential is described. 18 refs. 

An example of the copolymer composition produced in a batch reactor is shown in Figures 4.8 and 4.9 for a MMA-BA comonomer system. A seeded batch emulsion copolymerisation is simulated with a particle concentration Np of 2.6 x 10 ° particles per m water phase and an initial molar ratio of MMA and BA equal to one. The reactivity ratios and fBA used in the simulation are 2.24 and 0.414, respectively (Vicente, 2001). Partition coefficients, see Equation 4.21, were used to accoimt for monomer partitioning (Vicente, 2001). 

Figure 4.8 Simulated data for the seeded batch emulsion copolymerisation of MMA and BA, initial molar ratio of BA and MMA is one (a) instantaneous and cumulative copolymer composition (b) ratio of the concentration of monomer in the polymer particles referred to BA, %a = [BA]p/([BA]p + (MMA]p) (c) partial and overall conversions (d) rates of polymerisation.

The copolymer composition distribution can be calculated from the data collected in Figure 4.8 for the instantaneous composition and the time evolution of the overall conversion. Figure 4.9 displays the copolymer composition distribution for batch seeded emulsion copolymerisations of BA and MMA simulated with two initial monomer compositions one with 50mol% BA and 50mol% MMA and one with 90mol% BA and 10mol% MMA. 

Figure 4.11 shows simulated data for two-seeded semi-batch emulsion copolymerisations of BA and MMA carried out with feeding times of 3 and 6h, respectively. Figures 4.11(a) and (b) present the cumulative and instantaneous copolymer compositions. The results in the Figures 4.11(a) and (b) clearly demonstrate that the steady state is achieved in both cases. However, for the addition period of 6 h the fraction copolymer with a composition deviating from the desired composition of 0.5 is smaller than for the addition period of 3 h. Furthermore, the cumulative composition is closer to 0.5 for the 6 h addition period than for the 3 h addition. In comparison with the batch process, the composition drift is almost negligible as displayed in Figure 4.11 (d) which shows a very narrow chemical composition distribution (CCD) centred at 0.5. 

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