Surface free energies polymer blends

When we now consider a thin film of thickness D, Eq. (41) must be supplemented by boundary conditions of the same type as in the polymer blend case, Eqs. (7) and (10), i.e. we add a (bare) surface free energy contribution to the free energy that accounts for preferential attraction of one kind of monomers to the walls, missing neighbors in the pairwise interactions, and possible changes in the pairwise interactions near the surface. As in the blend case, this surface contribution is taken locally at the walls only and expanded to second order in the local order parameter /(z). Per unit area of the wall, this free energy is written as... 

A conventional understanding of the surface segregation from polymer blends is that the surface should be enriched in the component with lower bare surface free energy fs, regardless of the value of bulk composition This is however true only when (-dfs/d(j))s does not change its sign when surface concentration is varied (see Fig. 14b). For such blends, surface enrichment in the same... 

For high molecular weight (M — °o) binary blends, the Helfand and Tagami theory predicts that in binary blends (i) the interfacial thickness, A/ is inversely proportional to the interfacial tension coefficient,v , the product, A/ v being independent of the thermodynamic interaction parameter, X, (ii) the surface free energy is proportional to (iii) the chain-ends of both polymers concentrate at the interface (iv) any low molecular... 

Figure 3.8. Surface free energy of folding, (T, as a function of the PMMA content for PEG/PMMA blends using two PEG polymers differing in molecular weight (2 and 10 kg/mol) [Martuscelli, 1984].

Application of the PS-PDMS coating onto the PS base polymer was carried out by solution-blending base PS with small amounts of PS-PDMS products in THE Solutions were cast onto glass slides for surface energy (contact angle) measurements. These measurements were done in order to calculate surface free energy quantities, based on various model equations (Cai, 1997). Static contact angles were obtained from video capture methods with the aid of software for pixel-based calculations. Results of these measurements have been qualitatively consistent, and typically shown in Fig. 4.6.4. 

A number of polymer surface parameters, e.g. surface free energy and surface charge, are responsible for blood interaction phenomena. Regarding the correlation of hydrophilidty and thrombocyte adhesion, Ikada et al. determined a maximum of thrombocyte adhesion for a contact angle region between 60 and 80° [95]. Van Wachem et al. showed that the best blood compatibility of polymer blends is achieved for moderate wettability [96]. The influence of polar and dispersive components of the surface tension on blood compatibility was described by Kaelble and Coleman [97,98]. They found that polymers with high dispersive (y ) and low polar components (yP) of surface tension show better blood compatibility than polymers with low dispersive interactions. Furthermore, a nega-... 

Folded Surface Free Energy in Miscible Polymer Blends by Isothermal Melt Crystallization... 

In Section 1.3 we continue the discussion of Monte Carlo simulations of polymer blends and polymer solutions, but with the emphasis on interfaces that result in the context of phase separation interfaces between coexisting phases in the bulk (liquid-liquid interfaces in a blend, liquid-vapor-type interfaces in a solution) and at solid external walls. It will be shown how all the surface free energies entering Young s formula for the contact angle of droplets can be determined, and how one can estimate the location of wetting transitions. Coarse-grained models are the focus of this section. 

---