PMMA solvent

Binary solutions of CTAATFA-CH2Q2 (60 40 vA ), PET/solvent and PMMA/solvent were prepared and mixed in various ratios to obtain ternary solutions. After a lapsed time of 2 weeks, the solutions were observed visually and microscopically. The results are summarized in Table X. In agreement with Rory s prediction, the anisotropic phase is rich in CTA and the isotropic phase rich in PMMA or PET. However, at least within experimental error and in the timeframe of these experiments, the flexible polymer (PMMA or PET) was not completely excluded from the anisotrq>ic phase, contrary to results reported for other combinations of a flexible and a rigid polymer (20-22). 

For polystyrene (benzene solution) we used a diagram of Marzolph and Schulz (22). The values for PMMA (solvent CHCI3) were obtained with the formula (7)... 

Column Preparation. PMMA column was prepared using the procedure described by Pawlisch (361. The film thickness was inferred from the values of diffusivities measured with a second PMMA column whose thickness was measured using a destructive characterization technique. The column used in this study had an axial length of 17.78 m, an inner radius of 367 pm, and a film thickness of 5.3 pm. This column was used to measure diffusivities for the PMMA/solvent systems in a temperature interval from 70°C to 160°C. For each temperature, measurements were taken at three different carrier gas flow rates. Replicate measurements were made at each flow rate, and replicate elution curves were obtained at some of the conditions to evaluate reproducibility. 

PC/PMMA Solvent casting in THF, Phase separation, solvent induced Saldanha and Kyu, 1987... 

The same selective dissolution method can in fact be used even without an additive. When the minority component is selectively solvated then dried, the chains are left coating the matrix phase of the majority matrix, in an ultrathin film, the chains also migrate to cover the free surface on drying, leaving an empty pore in what was the center of the minority domain. Porous arrays up to around 30 nm thick based on PS-h-PMMA [72] (trifluorotoluene as selective PMMA solvent], PS-h-PVP [73] and PMMA-h-PVP [57] (ethanol as PVP solvent] have been created in this way. 

Disperse blue 72 Solvent green 3 Solvent green 28 Solvent red 111 Solvent red 135 colorant, PMMA Solvent red 179 colorant, PMMA Solvent violet 13 colorant, PMMA Solvent violet 36 colorant, PMMA... 

Polymer solvent interactions determine several properties, sueh as, solubility, solvent retention, plastieizer aetion, wettability, adsorption and adhesion. The solubility parameter is an important eriterion for the choice of solvents. However, acid-basic characters of bofli solvent and polymer are also determinant parameters, which can affect the solution and final film properties. This part, devoted to the influence of acid-base interactions on the aggregation of poly(methyl methacrylate) will first present some recent concepts in acid-base interactions, followed by two practical examples based on experimental results obtained for PMMA/solvent systems. 

The samples are completely soluble in typical PS and PMMA solvents such as toluene or tetrahydrofuran. 

L. Giebel, R. Borsali, E. W. Eischer, and M. Benmouna. Dynamic light scattering from PDMS/PMMA/solvent effect of optical properties. Macromolecules, 25 (1992), 4378 381. 

Anotlier model system consists of polymetliylmetliacrylate (PMMA) latex, stabilized in organic solvents by a comb polymer, consisting of a PMMA backbone witli poly-12-hydroxystearic acid (PHSA) chains attached to it [10]. The PHSA chains fonn a steric stabilization layer at tire surface (see section C2.6.4). Such particles can approach tire hard-sphere model very well [111. 

Common examples of the high Tg macromers are based on polystyrene or polymethylmethacrylate (PMMA) polymers of sufficiently high molecular weight to have a high T (typically on the order of 70-100°C as measured by differential scanning calorimetry) and also to make them immiscible with the acrylic polymer backbone once the solvent or heat has been removed. Typical molecular weight of the polystyrene or PMMA macromers is on the order of 5000-10,000 Da. Their generic structure can be pictured as in Fig. 13 (shown there for polystyrene). 

Yamamoto and Minamizaki [159] disclose the use of a curable silicone based release agent blended with resin particles which swell or are soluble in organic solvent. Coatings made with such blends can be written on with solvent based inks. For example, an addition cure silicone network containing 20 wt% 0.1 p,m diameter PMMA particles exhibited both good writeability (no ink dewetting and smear free) and a low release force of 10 g/cm for a PSA tape. 

Polymethyl Methacrylate (PMMA), This material has exceptional optical clarity and resistance to outdoor exposure. It is resistant to alkalis, detergents, oils and dilute acids but is attacked by most solvents. Its peculiar property of total internal reflection is useful in advertising signs and some medical applications. 

Suppose we have a physical system with small rigid particles immersed in an atomic solvent. We assume that the densities of the solvent and the colloid material are roughly equal. Then the particles will not settle to the bottom of their container due to gravity. As theorists, we have to model the interactions present in the system. The obvious interaction is the excluded-volume effect caused by the finite volume of the particles. Experimental realizations are suspensions of sterically stabilized PMMA particles, (Fig. 4). Formally, the interaction potential can be written as... 

In-column solvent Column size (mm) Theoretical plate number Exclusion limit PMMA - Particle size (/ttn) Pore size (A) Flow Rate (ml/min) Maximum pressure (kgf/cm ) Maximum temperature (°C)... 

Because we wanted to suppress the effects of thermodynamic quality of the eluent toward the polymer probes, we therefore looked for liquids that would be thermodynamically good solvents for PMMA. At the same time, one solvent should promote polymer adsorption whereas the others should promote desorption. 

Chloroform has lower affinity toward silica gel-based adsorbents than THF. PMMAs were fully retained from this solvent on the nonmodified silica gel even in the presence of a 1% ethanol stabilizer (14). It has been shown that PMMAs were not retained even within the most interactive PS/DVB column using chloroform stabilized with 1% ethanol. Chloroform is considered a weak displacer. 

It is evident from these results that the interactive properties of the investigated SEC PS/DVB or DVB gels are very different. Because polar electroneutral macromolecules of PMMA were more retained from a nonpolar solvent (toluene) than from polar ones (THF, chloroform), we conclude that the dipol-dipol interactions were operative. Columns No. 1 and No. 2 were very interactive and can be applied successfully to LC techniques that combine exclusion and interaction (adsorption) mechanisms. These emerging techniques are LC at the critical adsorption point (18), the already mentioned LC under limiting conditions of adsorption (15,18), and LC under limiting conditions of desorption (16). In these cases, the adsorptivity of the SEC columns may even be advantageous. In most conventional SEC applications, however, the interactive properties of columns may cause important problems. In any case, interactive properties of SEC columns should be considered when applying the universal calibration, especially for medium polar and polar polymers. It is therefore advisable to check the elution properties of SEC columns before use with the... 

The effects of increasing the concentration of initiator (i.e., increased conversion, decreased M , and broader PDi) and of reducing the reaction temperature (i.e., decreased conversion, increased M , and narrower PDi) for the polymerizations in ambient-temperature ionic liquids are the same as observed in conventional solvents. May et al. have reported similar results and in addition used NMR to investigate the stereochemistry of the PMMA produced in [BMIM][PFgj. They found that the stereochemistry was almost identical to that for PMMA produced by free radical polymerization in conventional solvents [43]. The homopolymerization and copolymerization of several other monomers were also reported. Similarly to the findings of Noda and Watanabe, the polymer was in many cases not soluble in the ionic liquid and thus phase-separated [43, 44]. 

The cationic nature of the copper(I) catalyst means that it is immobilized in the ionic liquid. This permits the PMMA product to be obtained, with negligible copper contamination, by a simple extraction procedure with toluene (in which the ionic liquid is not miscible) as the solvent. The ionic liquid/catalyst solution was subsequently reused. 

Studies of PMMA-based ionomers also demonstrate the influence of thermal treatment on deformation modes (16). For Na salts of PMMA-based ionomers of 6 and 12 mol% that were cast from DMF, only crazes were observed on straining. However, after an additional heat treatment (48 h at 160°C), which also removes any DMF solvent that is present, shear deformation zones are induced. Hence, the ionic cluster phase, which was destroyed by the polar solvent, has been restored by the heat treatment. 

Depending on the chemical structure of the MAI, a suitable solvent is sometimes needed to get a homogenous state of reaction mixture. Even if using the same combination of comonomers, for example, to prepare PMMA-b-poly(butyl acrylate) (PBA), the selection of the using order of comonomers for the first step or second step would affect the solvent selections, since PMMA is not easily soluble to BA monomer, while PBA is soluble to MM A monomer [28]. 

Figure 4.8 shows the fluorescence anisotropy decay curves for PMMA brushes with various graft densities swollen in benzene and acetonitrile. Benzene and acetonitrile are good and 0 solvents for PMMA. As clearly shown in this figure. 

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