Pseudo poly molecular weights

Tadros (1982) has presented theoretical potential energy diagrams for four different molecular weight stabilizing moieties. These were calculated using the formulae of Hesselink et al. (1971) and included the van der Waals attraction between the two latex particles. Poly(vinyl alcohol) was taken as the steric stabilizer. The results are shown in Fig. 11.5. As would be expected, any increase in the molecular weight moves the position of the pseudo-secondary minimum away from the surface, whilst at the same time decreasing its depth. 

Carbonates (ester of carbonic acid) are functional groups in which the carbon atom is surrounded by three oxygen atoms. This structure consists of two single and one double bonds. Carbonate-based pseudo poly(amino acids) are the first bioactive polymers to be synthesized and have been reported initially by Kohn [40,41]. The molecular weights of these polymers range from 120 to 450 kDa [40,41]. Their... 

The basic reaction scheme for formulating urethane-based pseudo poly(amino acids) requires a reaction of a diisocyanate with a diol in the presence of stannous oc-toate as a catalyst. Depending on their properties, either the diol or the diisocyanate could serve as the hard segment (h) or soft segment (s) as reported in Table 12.4. Several poly(urethanes) also include a diol- or diamine-based chain extender to yield a higher molecular weight product. 

Polymerization of diallg l vinylphosphonate monomers was nevertheless efficiently carried out in the presence of lanthanide derivatives and especially cyclopentadienyl lanthanide complexes, used both as initiators and catalysts. Very recently, Shen et al performed the synthesis of poly (diethyl vinylphosphonate) using a lanthanide tris(borohydride) below 50 °C. The authors showed that the polymerization eould be controlled and proceeds under pseudo-first-order kinetics, giving rise to high molecular weight polymers, i.e. ranging from 20 to 40 kDa with molecular weight dispersity below 1.7. 

Figure 3.4 Time evolution of weight average molecular weight as a function of time for poly(lactic-co-glycolic acid) microparticles with different sizes. Symbols represent experimental points, whereas solid lines represent pseudo-first order kinetic curves.

Figure 1 shows the partial phase diagram of the pseudo-temary system SDS/xylene-pentanol (1 l)/water. hi absence of any further additive the system shows the seper-ated w/o (L2 phase) and o/w (LI phase) microemulsions. As aheady described before, due to the presence of the nonionic polymer poly(ethylene glycol) an enlargement of the isotropic phase is induced and a phase channel, connecting the LI and L2 phase is formed at lOwt. % of PEG [36]. Our own investigations have shown that the dimensions of the phase channel are influenced by the polymer concentration, molecular weight, and also by the temperature [37]. 

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