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Polymerization

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Reversible Addition - Fragmentation Chain Transfer In Microemulsions: Effect Of Chain Transfer Agent Aqueous Solubility, Jennifer M. O'Donnell, Eric W. Kaler Jan 2010

Reversible Addition - Fragmentation Chain Transfer In Microemulsions: Effect Of Chain Transfer Agent Aqueous Solubility, Jennifer M. O'Donnell, Eric W. Kaler

Jennifer M. Heinen

Microemulsion polymerizations are attractive for investigating compartmentalization effects in heterogeneous reversible addition - fragmentation chain transfer (RAFT) polymerizations because the propagating radicals are segregated into surfactant stabilized polymer particles, which drastically reduces the effects of biradical termination, Also, microemulsion polymerizations do not involve the large monomer droplets that are present in emulsion and miniemulsion polymerizations. RAFT microemulsion polymerizations of butyl aery late with a high water solubility chain transfer agent, methyl-2-(O-ethylxanthyl)propionate (MOEP), and a low water solubility chain transfer agent, methyl-2-(O-dodecylxanthyl)propionate (MODP), were investigated to determine the effect of chain transfer agent compartmentalization on the control of the polymerization. The …

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Microstructure Evolution And Monomer Partitioning In Reversible Addition - Fragmentation Chain Transfer Microemulsion Polymerization, Jennifer M. O'Donnell, Eric W. Kaler Jan 2008

Microstructure Evolution And Monomer Partitioning In Reversible Addition - Fragmentation Chain Transfer Microemulsion Polymerization, Jennifer M. O'Donnell, Eric W. Kaler

Jennifer M. Heinen

Small-angle neutron scattering (SANS) studies of reversible addition - fragmentation chain transfer (RAFT) microemulsion polymerizations of butyl acrylate and 2-ethylhexyl acrylate with the RAFT agent methyl-2-(O-ethylxanthyl) propionate (MOEP) allow the observed rate retardation to be attributed to slow fragmentation of the macro-RAFT radical. Microemulsion polymerization allows the RAFT mechanism to be investigated in the absence of termination reactions so that the cause of the rate retardation frequently observed in both homogeneous and heterogeneous polymerizations may be isolated. However, the concentration of monomer at the locus of polymerization (Cmon(part)) must be known as a function of conversion before a mechanistic study …

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Effect Of S(Pi) On The Polymerization Of Liquid Sulfur And The Nature Of S(Pi), William Macknight, J. A. Poulis, C. H. Massen Dec 1966

Effect Of S(Pi) On The Polymerization Of Liquid Sulfur And The Nature Of S(Pi), William Macknight, J. A. Poulis, C. H. Massen

William MacKnight

The Tobolsky-Eisenberg theory serves to explain the equilibrium polym­erization of sulfur in terms of the dependence of S8 (ring) concentration on temperature and the dependence of number-average degree of polymeri­zation on temperature. The predictions of the theory are completely in accord with experiment. In this paper it is shown that it is possible to take the presence of another component in the melt, S,,, into account, using a slightly modified version of the Tobolsky-Eisenberg theory. When this is done it is found that the earlier conclusions remain valid. The molecular complexity and structure of Sw is also discussed.

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