Phase separation of polymer blends

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... 

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-... 

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. 

Optical microscope Fluorescent microscope Phase separation of polymer blends [37]... 

Confocal microscope Phase separation of polymer blends [38,39] Protein/polymer colocalization in polymeric films [40] Polymer blend in microparticles [41 ]... 

Phase Separation of Polymer Blends Driven by Temporally and Spatially Periodic Forcing... 

Phase separation of polymer blends and block copolymers. Confining polymer blends and block copolymers between surfaces may influence the phase separation process, as a consequence of the preferential affinity of one of the components for the interface. Since the pioneer works of Reich and Cohen [26] and later by Nesterov et al. [27], Ball and Essery [28], and Jones [29] amongst others much work has been done to understand the mechanisms of phase separation in polymer thin films. The presence of substrate-film and/or film-air interfaces introduces an additional complexity compared to bulk phase separation processes [30-35]. Complex structures can be produced by slight differences on parameters... 

Self-assembly and microphase separation Phase separation of polymer blends and/or block copolymers Random structures (polymer blends) and self-assembled nanostructures (block copolymers) Nanometer to micrometer Phase separation influenced by film thickness, temperature and substrate [36. 130, 135-141]... 

Reich, S., Cohen, Y. Phase separation of polymer blends in thin films. J. Polymer Sci. A2 Polymer Phys. 19(8), 1255-1267 (1981)... 

Gutmann, J.S., Muller-Buschbaum, P., Stamm, M. Complex pattern formation by phase separation of polymer blends in thin films. Faraday Discuss. 112, 285-297 (1999)... 

In Fig. 11.3, we made a comparison between the binodals obtained from dynamic Monte Carlo simulations (data points) and from mean-field statistical thermodynamics (solid lines). First, one can see that even with zero mixing interactions B = 0, due to the contribution of Ep, the binodal curve is still located above the liquid-solid coexistence curve (dashed lines). This result implies that the phase separation of polymer blends occurs prior to the crystallization on cooUng. This is exactly the component-selective crystallizability-driven phase separation, as discussed above. Second, one can see that, far away from the liquid-solid coexistence curves (dashed lines), the simulated binodals (data points) are well consistent... 

Yu et al. (2011) studied rheology and phase separation of polymer blends with weak dynamic asymmetry ((poly(Me methacrylate)/poly(styrene-co-maleic anhydride)). They showed that the failure of methods, such as the time-temperature superposition principle in isothermal experiments or the deviation of the storage modulus from the apparent extrapolation of modulus in the miscible regime in non-isothermal tests, to predict the binodal temperature is not always applicable in systems with weak dynamic asymmetry. Therefore, they proposed a rheological model, which is an integration of the double reptation model and the selfconcentration model to describe the linear viscoelasticity of miscible blends. Then, the deviatirMi of experimental data from the model predictions for miscible... 

The phase boundaries and the kinetics of phase separation of polymer blends are very rich areas of investigation, with, additionally, important technological applications. 

The experimental procedures for thermally inducing phase separation of polymer blends by DSC technique are as follows. 

As diffusion phenomena are extremely important in miscible blend formation and phase separation of polymer blends, these phenomena are discussed in detail in this chapter. 

Widmaier and Meyer [205] studied the structure of an ABA polystyrene-fc-isoprene block copolymer as a function of temperature by osmium tetroxide staining thin cast films. Hsiue and Yang [206] studied the morphology and properties of a-methylstyrene butadiene diblock copolymer films cast from several solvents. Films at a 0.1% concentration were cast on water and stained with 2% osmium tetroxide solution for 1 h. The microstructure was shown to differ for films cast from different solvents as there is a pol5mier-solvent interaction. Reich and Cohen [207] studied the phase separation of polymer blends in thin films and compared the behavior to that of the bulk material, as it is well known that phase... 

From the dynamic viscoelastic properties, valuable information about the compatibility and phase separation of polymer blends [86-91] can be obtained, based on their sensitivity to variations in the morphology of blends. Some emulsion models for polymer blends [92-97] have been used to estimate the interfacial tension of HDPE/PS (80/20) blends. Chen et al. [98] used the linear rheological properties of... 

In this chapter, attention will be focused on applications of the Cahn-Hilliard equation on the numerical simulation of an inhomogeneous polymer blend. The numerical model of a binary polymer system and a polymer-polymer-solvent system will be reviewed as examples to illustrate the application of such modeling methodologies. Attention will be paid in particular to a diffusion-controlled system with no mechanical flow, and the effects of substrate patterning will be taken into consideration to highlight the influences of external attraction during the phase separation of polymer blends. The results of the numerical simulation will then be verified using realistic experimental results, on a quantitative basis. 

The properties of the external surface can significantly alter phase separation in a thin polymer film. In extensive experimental investigations of the phase separation of polymer blends directed by patterned substrates [1,56,58,60,80-88] it was observed that the domain size evolved in a power law relation with time. The composition wave was normal to, and propagates inward from, the functionalized substrate. Likewise, processing parameters such as pattern size in the substrate were seen to affect refinement of the morphology. 

Subsequently, a numerical model was introduced to simulate self-assembly by the phase separation of polymer blends on a heterogeneously functionalized substrate patterns. From thermodynamic principles, when polymer blends are quenched into the spinodal region in the phase diagram, phase separation can be initiated from small composition fluctuations in the blend. The Cahn-Hilliard equation is used to describe the energy profile in the domain with varying... 

Kielhom, L. and Muthukumar, M. (1999) Phase separation of polymer blend film near patterned surfaces./. Chem. Phys., Ill (5), 2259-2269. 

Then in section III, we analyze the liquid-liquid phase separation of polymer blends in solvents of various quality. Particular emphasis is put on the case of a common good solvent and on the discussion of the critical properties of demixing which are very unusual as the critical behavior is not of the mean-field type (except for very long chains and low incompatibility degrees) and is als very different from that of low molecular weight ternary mixtures. We also focus on well- demixed systems and consider the interfacial properties following the work of Broseta et al. ... 

Much of the preceding discussion has included semicrystalline thermoplastics and blends that were used as examples for discussions of structure and process. A brief literature review of impact modified thermoplastics follows. Reich and Cohen [339] studied the phase separation of polymer blends in thin films and compared... 

---