Compatibility of polymer

In a thermodynamic sense, the compatibility of polymers is similar to the dissolving solute in a solvent. The thermodynamic standard of solubility is the free energy of mixing Ga. If AGm < 0, then two components are soluble to each other. According to the definition ... 

One practical example of demixing that might be attributed to a difference in crystallizability is the incompatibility in blends of polymers with different stereochemical compositions. The stereochemical isomers contain both chemical and geometrical similarities, but differ in the tendency of close packing. In this case, both the mixing energy B and the additional mixing entropy due to structural asymmetry between two kinds of monomers are small. However, the stereochemical differences between two polymers will result in a difference in the value of Ep. Under this consideration, most experimental observations on the compatibility of polymer blends with different stereochemical compositions [89-99] are tractable. For more details, we refer the reader to Ref. [86]. 

Finally, we should mention the phenomenon of incompatibility of mixtures of polymer solutions. It applies to nearly all combinations of polymer solutions when the homogeneous solutions of two different polymers in the same solvent are mixed, phase separation occurs. For example, 10% solutions of polystyrene and poly(vinyl acetate), each in benzene, form two separated phases upon mixing. One phase contains mainly the first polymer, the other phase mainly the second polymer, but in both phases there is a certain amount of the other polymer present. This limited compatibility of polymer mixtures can be explained thermodynamically and depends on various factors, such as the structure of the macromolecule, the molecular weight, the mixing ratio, the overall polymer concentration, and the temperature. 

The compatibility of polymers can be related to their 5 values. Thus various polyolefins are compatible, and many of the polyalkyl acrylates and alkyl methacrylates are also compatible with each other (see Tables 8.1, 8.2). 

When two polymeric systems are mixed together in a solvent and are spin-coated onto a substrate, phase separation sometimes occurs, as described for the application of poly (2-methyl-1-pentene sulfone) as a dissolution inhibitor for a Novolak resin (4). There are two ways to improve the compatibility of polymer mixtures in addition to using a proper solvent modification of one or both components. The miscibility of poly(olefin sulfones) with Novolak resins is reported to be marginal. To improve miscibility, Fahrenholtz and Kwei prepared several alkyl-substituted phenol-formaldehyde Novolak resins (including 2-n-propylphenol, 2-r-butylphenol, 2-sec-butylphenol, and 2-phenylphenol). They discussed the compatibility in terms of increased specific interactions such as formation of hydrogen bonds between unlike polymers and decreased specific interactions by a bulky substituent, and also in terms of "polarity matches" (18). In these studies, 2-ethoxyethyl acetate was used as a solvent (4,18). Formation of charge transfer complexes between the Novolak resins and the poly (olefin sulfones) is also reported (6). 

Glass transition temperature is one of the most important parameters used to determine the application scope of a polymeric material. Properties of PVDF such as modulus, thermal expansion coefficient, dielectric constant and loss, heat capacity, refractive index, and hardness change drastically helow and above the glass transition temperature. A compatible polymer blend has properties intermediate between those of its constituents. The change of glass transition temperature has been a widely used method to study the compatibility of polymer blends. Normally, the glass transition temperatme of a compatible polymer blend can be predicted by the Gordon-Taylor relation ... 

Polymaric plasticizars can ba mada by (1) Internal plasticization whoroby a monomor is copolymorizod with on which tends to yield soft polymers by itself (2) Mechanical mixing of a polymerizable monomer with a polymer, followed by polymerization (3) Mechanical blending of two compatible polymers. In many cases It Is necessary to combine the polymeric plasticizer with a liquid plasticizer because the compatibility of polymers with each other is generally limited. From the industrial polymeric plasticizers, especially polyesters of low degree of polymerization and several copolymers of butadiene with acrylonitrile, acrylic add esters and fumaric add esters were studied. These polymeric plasticizers are characterized by good compatibility and improved cold resistance of the final product. 

No attempt is made to review solution theory. For a thorough treatment on this subject, numerous authoritative monographs (3, 4, 5, 6, 7) are available. We discuss only those thermodynamic considerations which have some bearing on the discussion of compatibility of polymer blends. 

Since most other modeling techniques for polymers are extremely demanding, the limited capabilities of COSMO-RS for efficient prediction of solubilities in polymers can be of great help in practical applications when suitable polymers with certain solubility requirements are desired. One application may be the selection of appropriate membrane polymers for certain separation processes. Predictions of drug solubility in polymers are sometimes of interest for pharmaceutical applications. Furthermore, it is most likely that COSMO-RS can also be used to investigate the mutual compatibility of polymers for blends. This aspect, and many other aspects of the potential of COSMO-RS for polymer modeling, still awaits systematic investigation. 

Since the compatibility of macromolecules is extensively discussed in many works on the -parameter18, it is treated here only briefly. When considering the compatibility of polymers, one must naturally give thought to weak inter-macromolecular interactions, for example, van der Waals force, dipole-dipole interaction, and so on. 

Compatibility of polymers implies a semi-quantitative measure can be used to predict whether two or more polymers are compatible. The use of one of the semi-quantitative approaches, solubility parameter, was demonstrated by Hughes and Britt (22). It was concluded (8) that one parameter was insufficient to predict the compatibility. In this paper, we now introduce critical surface tension which is determined from the surface properties of a polymer. Though both of these parameters have been related by Gardon (15), we are inclined to use the latter because we can further describe the wettability between two polymers. For instance, by the use of yc, we can predict equally well that compatibility between polystyrene and polybutadiene can be improved if butadiene is... 

Klotz, S. Schuster, R. H. Cantow, H. -J., "Compatibility of Polymers in Polymer Blends Investigated by Gas Chromatography," Makromol. Chem. 187, 1491 (1986). 

Interest in the adhesion of dosage forms to epithelial surfaces has heen aroused hy the possihility of deliberate contact between oral dosage forms and the gut wall to retard the rate of transit down the gastrointestinal tract, but also by the possibility of dosage forms accidentally adhering to the oesophagus or other epithelial surfaces. Adhesive preparations have been formulated for diverse tasks such as the topical treatment of stomatitis and the administration of insulin. The adhesive nature of transdermal patches is important, as is the adhesion of film coats to tablet surfaces. Adhesion of erythrocytes and bacterial cells to polymer surfaces is also of importance in the understanding, respectively, of blood compatibility of polymers and bacterial infection mediated by catheters. 

Shaded cells indicate compatibility of polymer with solvent or crosslinker PLA poly(lactic acid), PGA poly(glycolic acid) PLGA poly(lactic-co-glycolic acid), PCL poly(e-caprolactone), PEU poly(ester urethane), PEEUU poly(ester ether urethane), PVA poly(vinyl alcohol), PEO poly(ethylene oxide), HA hyaluronic acid, DMF W,W-dimethylformamide, A4 acetic acid, FA formic acid, DCM dichloromethane, HFIP hexafluoroisopropanol, THF tetrahydrofuran, GA glutaraldehyde, NMMO N-methyl-morpholine A -o, idc/water (NMMO/water)... 

The compatibility of polymer blends has been a snbject of mnch interest. Polymer blends are systems with two (or more) polymers, most of which are incompatible (immiscible). Finding compatible polymer pairs is an important task in the design of snch advanced materials. Moreover, several new polymeric materials with interesting properties involve novel structures, which go beyond the well-known ones (linear, branched, cross-linked, and network). Such novel strnctnres, e.g., starlike polymer and dendrimers may require new concepts for selecting proper solvents and generally for nnderstanding their solnbility behavior. "... 

Such cubic equations of state as van der Waals correlate very satisfactorily the UCST-type behavior for polymers solutions, as shown by Harismiadis et al. ° A generalized correlation of the interaction parameter of the van der Waals equation of state for polymer blends based exclnsively on polystyrene blends has been presented. By nsing this equation, the van der Waals eqnation of state can be used as a predictive tool for investigating the compatibility of polymer blends. Predictive GC thermodynamic methods such as Entropic-FV, GC-Flory, UNIFAC, and UNIFAC-FV perform rather poorly, at least from a quantitative point of view. Entropic-FV performs best among these models, on a qualitative basis. For semiquantitative predictions in polymer blends, the approach proposed by Coleman et al. is recommended. 

Extrapolation of the concept of the compatibility of polymers with different structures but similar solubility parameters to the construction of effective compatibilizing agents leads to the use of block and graft copolymers having segments with suitable solubility parameters to compatibilize polymers which differ both in structure and solubility parameter. Thus, an AB block or graft copolymer compatibilizes polymers A and C when C has a solubility parameter similar to that of B, polymers D and B when D has a solubility parameter similar to that of A, and polymers C and D when the solubility parameter of C is similar to that of B, and D has a solubility parameter similar to that of A. 

Thermodynamic compatibility of polymer CM components is observed rather infrequently as there is not commonly necessary to reach it. Polymer materials can be produced with preset properties even in conditions of limited compatibility between components. It is desirable to attain a thermodynamic non-equilibrium state for these materials for specific purposes, e.g. corrosionproofing by inhibited plastics. Process compatibility of components, on the other hand, should be treated as a requisite quality of CM. 

Thermodynamic compatibility of polymers and Cl, and the technology as well, are involved in an integral composite material. Difficulties arising can be overcome by creating quasi-compatible composites. This is the direction in which materials science of inhibited plastics is progressing today. In Fig. 1.16... 

Columns can be washed with organic solvents to remove contaminants. This is not a problem with silica-based HIC columns. The compatibility of polymer-based HIC columns with organic solvents may be limited. Consult the manufacturer s recommendations ... 

Compatibility of two- and threecomponent systems of poly(vinyl chloride) with homo- and copolymers of methyl methacrylate and butyl methacrylate has been studied. The mixtures were tested for compatibility in the dynamic viscosity of polymer solutions, in microscopic observations in polarized light, as well as by dynamic mechanical measurements. It was found that poly(methyl methacrylate) and methacrylic copolymers were compatible with PVC. Poly(butyl methacrylate) appears to be incompatible with PVC. Estimation of solubility parameter values 6 made it possible to predict the compatibility of polymer pairs. Critical A6 value for compatible polymers has been found to be 0.5 (cal cm 3)1/2. 

The magnitude of intercomponent interactions is of basic importance in these systems, since it determines the structure of the composition. Thus, in majority of works on the subject the problem of the compatibility of polymers is discussed. Thermodynamic considerations indicate that compatibility is only seldom encountered in polymer systems . Free energy change AG, related to the formation of a two-component polymer system under constant pressure and temperature conditions, is given by... 

Compatibility of polymer and plasticizer implies solubility but there should also be a strong enough chemical interaction to insure longterm stability. 

The assembly process is a complex nonequilibrium process and depends on a number of other thermod5mamic and kinetic factors, including the viscosity of polymer systems, thickness of the film, compatibility of polymer... 

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