Phase separation in blends

As in the case of LCP/conventional polymer blending, little data exists on the blending of LCPs of different inherent chain architecture or mesophase symmetry. Publications from the laboratories of Ringsdorf [80] and Finkelmann [81] show phase separation in blends of sidechain nematics with other similar polymers or small molecule analogs. It is now established that, in contrast to the behavior of low molecular weight LCs, LCPs are often immiscible. 

Heinen W, Wenzel CB, Rosenmoeller CH, Mulder FM, Boender GJ, Lugtenburg J, de Groot HJM, Van Duin M, Klumperman B (1998) Solid-state NMR study of miscibility and phase separation in blends and semi-interpenetrating networks of 13C-labeled poly(styrene-co-acrylonitrile) and poly(styrene-co-maleic anhydride). Macromolecules 31 7404-12. 

The dependence of excitation transport on local chromophore concentration has been used to provide qualitative information on the characteristics of polymers in blends. Excimer fluorescence resulting from excitation transport has been employed to characterize polymer miscibility, phase separation and the kinetics of spinodal decomposition (1-31. Qualitative characterization of phase separation in blends (4.51 and the degree of chain entanglement as a function of sample preparation and history (6.71 has also been investigated through transport with trapping experiments. In these experiments one polymer in the blend contains donor chromophores and the second contains acceptors. Selective excitation of the former and detection of the latter provides a qualitative measure of interpenetration of the two components. 

Oigan SJ (1994) Phase separation in blends of poly(hydroxybutyrate) with poly(hydroxybutyrate-co-hydiox5rvalerate) variation with blend components. Polymer 35 86-92 Oigan SJ, Barham PJ (1993) Phase separation in a blend of poly(hydroxybutyrate) with poly(hydroxybutyrate-co-hydroxyvalerate). Polymer 34 459-467 Ouyang SP, Liu Q, Fang L, Chen GQ (2007) Construction of a p/w-operon-defined knockout mutants of Pseudcmonas putida KT2442 and their applications in poly(hydroxyalkanoate) production. Macromol Biosd 7 227—233... 

Lau S-F, Pathak J, Wunderlich B (1982) Study of Phase Separation in Blends of Polystyrene and Poly-a-methylstyrene in the Glass Transition Region. Macromolecules 15 1278-1283. 

Hu, Y., Hu, Y.S., Topolkaraev, V., Hiltner, A., and Baer, E. (2003) Crystallization and phase separation in blends of high stereoregular poly(lactide) with poly(ethylene glycol). Polymer, 44, 5681-5689. 

The phase separation in blend thin films also proceeds by the well-described bulk mode of nucleation and growth and spinodal decomposition. However, the conditions of phase separation during the formation of a blend thin film are significantly... 

Figures 9.4 and 9.5 show G and G" for two linear polymers, a poly(vinyl methyl ether) (PVME) with a molecular weight of 138,000 and a polystyrene (PS) with a molecular weight of 123,000, respectively. The data for each polymer have been moved horizontally along the frequency axis until they form a single curve. There is a substantial region of overlap, extending over three decades of frequency, so the superposition is clearly established. The shift factors needed to obtain overlap of the curves are shown as inserts. The reference temperature for each case was taken to be 84 °C this temperature has no significance other than being a convenient value for the particular application for which the data were obtained, which was a study of phase separation in blends of the two polymers. One of the significant uses of time-temperature superposition is made evident by focusing on the open and closed symbols in the PVME curves. The dynamic moduli are available over five orders...

Hill, M.J. and Puig, C.C. (1997) liquid-liquid phase separation in blends of a linear low-density polyethylene with a low-density polyethylene. J. Appl. Polym. Sci., 65, 1921-1931. 

Vogel C, Wessel E, Siesler HW. FT-IR imaging spectroscopy of phase separation in blends of poly(3-hydroxybutyrate) with poly(L-lactic acid) and poly(epsilon-caprolactone). Biomacromolecules 2008 9 523-527. 

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