Polystyrene-poly analyze

A variety of procedures were utilized to analyze this reaction mixture and to characterize a,10-diaminopolystyrene. Thin layer chromatographic analysis using toluene as eluent exhibited three spots with Rf values of 0.85, 0.09, and 0.05 which corresponded to polystyrene, poly(styryl)amine and a,w-diaminopolystyrene (see Figure 1). Pure samples of each of these products were obtained by silica gel column Chromatography of the crude reaction mixture initially using toluene as eluent [for polystyrene and poly(styryl)amine] followed by a methanol/toluene mixture (5/100 v/v) for the diamine. Size-exclusion chromatography could not be used to characterize the diamine since no peak was observed for this material, apparently because of the complication of physical adsorption to the column packing material. Therefore, the dibenzoyl derivative (eq. 5) was prepared and used for most of the analytical characterizations. 

Figure 8 (1., 6) shows the fractionation obtained by analyzing a mixture of polystyrene, poly(styrene co-n-butyl methacrylate) and poly(n-butyl methacrylate) with various n-heptane concentrations. 

The structures formed by polystyrene-poly(propylene imine) dendrimers have also been analyzed. Block copolymers with 8, 16, and 32 end-standing amines are soluble in water. They have a critical micelle concentration of the order of 10"7 mol/1. At 3x10 4 mol/l they form different types of micelles. The den-drimer with eight amine groups (80% PS) form bilayers. The dendrimer with 16 amine groups (65% PS) forms cylinders and the dendrimer with 32 amine groups (50% PS) forms spherical micelles [38,130,131]. These are the classical lamellar, cylindrical, and spherical phases of block copolymers. However, the boundary between the phases occurs at very different volume fractions, due to the very different packing requirements of the linear polymer and spherical dendrimer at the interphase. 

Phase separation of polystyrene/poly(vinyl methyl ether) blends was induced under spatially and temporally periodic forcing conditions by taking advantage of either photodimerization of anthracene or photoisomerization of /rt//i .9 stilbene chemically labeled on polystyrene chains. Significant mode election processes driven by these reactions were experimentally observed and analyzed for both cases. These experimental results reveal a potential method of morphology control using periodic forcing conditions. 

ESCA can also be used to analyze fracture surfaces, particularly those involving immiscible (asymmetric) interphases. While finely divided polymer blends offer some difficulties, plates of two different polymers welded together provide valuable model materials. Foster and Wool (19) and Willett and Wool (20) studied the polystyrene/poly(methyl methacrylate) interface welded at 125 and 140°C see Figure 12.5 (20). As described above, ESCA makes use of... 

Comprehensive two-dimensional liquid chromatography has seen a strong increase in popularity and in the number of applications in recent years. LC x SEC has been applied to a large number of problems in polymer science. For example, the technique has been used to provide a detailed analysis of polystyrene-poly(methyl methacrylate) diblock copolymers [29], to analyze well-defined star polylactides [30], and to study to the grafting reaction of methyl methacrylate onto EPDM [31] or onto polybutadiene [32]. 

The general procedure employed was as follows. A three-necked flask equipped with a magnetic stirring bar and three rubber septum was chaiged with alkyne-(PSt-azide)2 macromonomer (2 g, 0.263 mmol), PMDETA (109.5 p,L, 0.526 mmol) and DMF (13.3 mL). The flask was degassed by four freeze-pump-thaw cycles, and then placed in a water bath thermostated at 35 °C. After 2 min, CuBr (75 mg, 0.526 nunol) was introduced to start the poly-condensation under N2 flow. Samples were taken at timed intervals and precipitated into a mixture of methanol/water (90/10, v/v) and the products were washed with excess methanol. After drying in a vacuum oven overnight at 40 °C, the resultant hyperbranched polystyrene was analyzed by SEC and LLS. 

Aqueous samples may be analyzed by HPLC using a C-18 derivatized reverse phase column or on an underivatized polystyrene-divinylbenzene column such as Poly-RP CO (Alltech 1995) gradient acetonitrile and 0.01 A/ K,P04 at pH 7 (55 45) and the analyte detected by UV at 254 nm. 

Transparent Polymers. Amorphous thermoplastics, like poly (methyl methacrylate), polystyrene, SAN, PVC, or the cellulose esters are transparent and used for glazing, photographic film, blown bottles, or clear packaging containers. Only a few crystalline thermoplastics, like poly (4-methyl-l-pentane), where the crystalline and the amorphous phases have almost identical refractive indexes, or polycarbonate, which has smaller crystals than the wavelength of light, are also transparent. R. Kosfeld and co-workers analyzed the mobility of methyl groups in polycarbonate, poly (methyl methacrylate) and poly( -methyl styrene) by NMR spectroscopy. 

Many computational studies of the permeation of small gas molecules through polymers have appeared, which were designed to analyze, on an atomic scale, diffusion mechanisms or to calculate the diffusion coefficient and the solubility parameters. Most of these studies have dealt with flexible polymer chains of relatively simple structure such as polyethylene, polypropylene, and poly-(isobutylene) [49,50,51,52,53], There are, however, a few reports on polymers consisting of stiff chains. For example, Mooney and MacElroy [54] studied the diffusion of small molecules in semicrystalline aromatic polymers and Cuthbert et al. [55] have calculated the Henry s law constant for a number of small molecules in polystyrene and studied the effect of box size on the calculated Henry s law constants. Most of these reports are limited to the calculation of solubility coefficients at a single temperature and in the zero-pressure limit. However, there are few reports on the calculation of solubilities at higher pressures, for example the reports by de Pablo et al. [56] on the calculation of solubilities of alkanes in polyethylene, by Abu-Shargh [53] on the calculation of solubility of propene in polypropylene, and by Lim et al. [47] on the sorption of methane and carbon dioxide in amorphous polyetherimide. In the former two cases, the authors have used Gibbs ensemble Monte Carlo method [41,57] to do the calculations, and in the latter case, the authors have used an equation-of-state method to describe the gas phase. 

The enzymatic activity of a-chymotiypsin was evaluated in composites of poly(methyl metacrilate) with different carbon materials [91] demonstrating that the incorporation of SWCNTs into enzyme-polymer composites results in active and stable polymeric films. The release of the protein from the composite was evaluated measuring the enzymatic activity in the supernatant in contact with the composite. The results showed that in the case of SWCNTs the leaching of the protein from the composite was lower. This fact was attributed to the imion of the protein to the CNTs. The effect of other polymers such as polystyrene and poly(lactic acid) was also analyzed and the leaching of the protein was significant in the absence of SWCNTs. Only the hydrophobic ones (poly(methyl metacrilate)... 

The materials analyzed were blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) in various ratios. The two components are miscible in all proportions at ambient temperature. The photooxidation mechanisms of the homo-polymers PS and PVME have been studied previously [4,7,8]. PVME has been shown to be much more sensitive to oxidation than PS and the rate of photooxidation of PVME was found to be approximately 10 times higher than that of PS. The photoproducts formed were identified by spectroscopy combined with chemical and physical treatments. The rate of oxidation of each component in the blend has been compared with the oxidation rate of the homopolymers studied separately. Because photooxidative aging induces modifications of the surface aspect of the material, the spectroscopic analysis of the photochemical behavior of the blend has been completed by an analysis of the surface of the samples by atomic force microscopy (AFM). A tentative correlation between the evolution of the roughness measured by AFM and the chemical changes occurring in the PVME-PS samples throughout irradiation is presented. 

The composition of the PAA-g-PS graft copolymer reaction product and its purification, especially as far as the removal of unreacted PS-MA macromonomer by silica column chromatography is concerned, and the successful selective cleavage of the ferf-butyl ester under acidic conditions to render the graft copolyelectrolyte PAA-g-PS were analyzed by XH NMR spectroscopy and SEC. Figure 8a shows the SEC curves of the polystyrene macromonomer (PS-MA), the crude poly (ferf-butyl acrylate-gra/f-styrene) (PTBA-g-PS) and the PTBA-g-PS the polymethylacrylate (PMA) originates from esterification of the poly (acrylic acid) (PAA) obtained after complete saponification of the graft copolymer and represents the backbone. The XH NMR spectra of PSMA, PTBA-g-PS and of the final reaction product PAA-g-PS are shown in Fig. 8b. 

It was shown that several commercially available dyes bind with high selectivity in water to the immobilized and acetylated peptides. When aqueous solutions of the dyes were equilibrated with the encoded combinatorial library of 45,000 acylated tripeptides containing 14 different acyl substituents as end groups and 15 different L- and D-amino acids, immobilized on hydrophilic, poly(ethyleneglycol)-polystyrene (PEG-PS) beads for 24 h, only -0.1% of the beads turned intensely colored as a result of the staining of the dyes. These stained beads were analyzed... 

This chapter covers fundamental and applied research on polyester/clay nanocomposites (Section 31.2), which includes polyethylene terephthalate (PET), blends of PET and poly(ethylene 2,6-naphthalene dicarboxy-late) (PEN), and unsaturated polyester resins. Section 31.3 deals with polyethylene (PE) and polypropylene (PP)-montmorillonite (MMT) nanocomposites, including blends of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE). Section 31.4 analyzes the fire-retardant properties of nanocomposites made of high impact polystyrene (HIPS), layered clays, and nonhalogenated additives. Section 31.5 discusses the conductive properties of blends of PET/PMMA (poly (methyl methacrylate)) and PET/HDPE combined with several types of carbon... 

In one variation of the process the deforming stress is applied to a warm, soft plastic model which is then quenched to room temperature. The resulting locked-in stress may then be analyzed at leisure or, perhaps more conveniently, by cutting sections from the model and examining them separately. For this application, however, the plastic should have stress-optical stabihty. In this regard, unplastidzed transparent plastics such as poly(methyl methacrylate), polystyrene, and cast polyfallyl phthalate) are superior to plasticized materials such as cellulose acetate. 

More recently, in a series of papers [84-86], Brown has analyzed the improvement in adhesion between two immiscible polymers [i.e., poly(methyl methacrylate) (PMMA) and polyphenylene oxide (PPO)] by the presence of polystyrene-PMMA diblock copolymers. Since one of the blocks is PMMA and the other is polystyrene (PS), which is totally miscible with PPO, it was reasonably expected that the copolymer organizes at the... 

The first proof of the validity of this approach was given by Gankina et al. [19] for the analysis of block copolymers by thin layer chromatography. Column liquid chromatography was used by Zimina et al. [20] for the analysis of poly(styrene-b/ock-methyl methacrylate) and poly(styrene-Wock-terr-butyl methacrylate). However, the critical conditions were established only for the polar part of the block copolymers, i.e. PMMA and PtBMA, respectively. Thus, only the polystyrene block was analyzed. 

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