Phase separation, of polymers

For preparative purposes batch fractionation is often employed. Although fractional crystallization may be included in a list of batch fractionation methods, we shall consider only those methods based on the phase separation of polymer solutions fractional precipitation and coacervate extraction. The general principles for these methods were presented in the last section. In this section we shall develop these ideas more fully with the objective of obtaining a more narrow distribution of molecular weights from a polydisperse system. Note that the final product of fractionation still contains a distribution of chain lengths however, the ratio M /M is smaller than for the unfractionated sample. 

Thermodynamics and kinetics of phase separation of polymer mixtures have benefited greatly from theories of spinodal decomposition and of classical nucleation. In fact, the best documented tests of the theory of spinodal decomposition have been performed on polymer mixtures. 

The phase transitions, such as a phase separation of polymer solutions, a sol-gel transition, or a volume phase transition of gels, are always accompanied by conformation changes of polymers. Therefore, when the phase transitions are induced isothermally by external stimulation, the transitions cause efficient conformation changes. This contribution describes how such efficient stimuli-responsive polymer systems can be constructed. 

Further details of the phase separation of polymer mixtures were obtained by analyzing the high styrene phase sedimented at a weight concentration gB of benzene (Table II). 

PHASE SEPARATION OF POLYMER BLENDS IN LIGHT EMITTING DEVICES... 

Elsewhere in this book, Prof. Steiner describes the wealth of patterns arising from phase separation of polymer blends and different strategies to control this phase separation into... 

Emmerik, P. T. van Smolders, C. A., "Phase Separation of Polymer Solutions. The Calculation of the Cloudpoint curve with a Concentration and Temperature-Dependent Free Energy Correction Parameter," Eur. Polym. J., 9, 157 (1973). 

Kern, R. J., "Component Effects in Phase Separation of Polymer-Polymer-Solvent Systems," J. Polym. Sci., 21, 19 (1956). 

Li et al. studied the quality and activity of a catal3Tic system used in carbon nanotube (CNT) growth process using pRS [11]. By localized Raman mapping, the variation of the active metallic species (Fe, Co) over the oxide surface (CaCOs) was quantified and analyzed. In this study, it was observed that the compositional variation in the active species over the oxide surface affected the yield and morphology of the CNT. Mayo et al. employed pRS to study the phase separation of polymer-functionalized single-walled carbon nanotubes (SWCNTs) within... 

Mayo JD, Behai S, Adronov A (2009) Phase separation of polymer-functionalized SWNTs within a PMMA/Polystyrene blends. J Poiym Sci Poiym Chem 47 450-458 Cou JY, Lensch-Falk JL, Hemesath ER, Lauhon LJ (2009) Vanadium oxide nanowire Phase and orientation analyzed by Raman spectroscopy. J Appl Phys 105 034310-1-034310-6 Wang ZL (2004) Functional oxides nanobelts-materials, properties and potential applications in nanosystems and biotechnology. Annu Rev Phys Chem 55 159-196 Bliznyuk VN, Singamaneni S (2009) Polymer carbon nanotube composites. Encyclopedia of nanoscience and nanotechnology, (2012), ASP, Ed. H. S. Nalwa... 

However, a repulsive block copolymer exhibits different behavior in the composition effect on the phase separation of polymer blend. As observed in Fig. 21, unlike the case of attractive block copolymer, the retardation effect by the asymmetric block copolymer with/= 0.7 becomes rather worse than that by the sym-... 

A. Sariban and K. Binder (1988) Phase-Separation of polymer mixtures in the presence of solvent. Macromolecules 21, pp. 711-726 ibid. (1991) Spinodal decomposition of polymer mixtures - a Monte-Carlo simulation. 24, pp. 578-592 ibid. (1987) Critical properties of the Flory-Huggins lattice model of polymer mixtures. J. Chem. Phys. 86, pp. 5859-5873 ibid. (1988) Interaction effects on linear dimensions of polymer-chains in polymer mixtures. Makromol. Chem. 189, pp. 2357-2365... 

In this review, we introduce recent research works on polymer blends as studied by solid state NMR and focus on the miscibility and phase separation of polymer blends that are responsible for the improvement in their physical properties. 

Solid state NMR offers powerful tools for probing miscibility, phase separated structure and molecular motion in polymer blends and which may be beyond the resolution limits of conventional microscopic or thermal analysis. A large number of NMR works have been published and some of them were reviewed. In this review, therefore, we introduce recent research works on polymer blends by solid state NMR and focus on the miscibility and phase separation of polymer blends that are responsible for the improvement in their physical properties. 

Dodecyldimethyl-ammoniumethyl-methacrylate bromide Micellar Phase separation of polymer from the micellar solution >95% conversion [57]... 

The formation of lyophilic colloidal systems may also take place via phase separation of polymer solutions. A typical phenomenon that occurs upon phase separation is the formation of the so-called coacervates, which are characteristic nuclei containing higher concentration of polymer, as compared to that in the medium surrounding them. It is speculated that coacervation was a second stage (after the formation of adsorption layers) in the ordered structuring of organic matter on Earth. 

---