Polystyrene molecular characteristics

Table 8. Molecular characteristics of copolymers polystyrene-polyiethylene oxide) (SEO) and polybutadiene-polyfethylene oxide) (BEO)...

UG Ougizawa, T., Dee, G.T., and Walsh, D.J., PVT properties and equation of state of polystyrene. Molecular weight dependence of the characteristic parameters in equation-of-state theories (experimental data by D.J. Walsh), Polymer, 30, 1675, 1989. 

Systematie study of the cosolvency phenomenon has been practically limited to polymethylmethacrylate " and polystyrene. " The cosolvency is usually explained in terms of the molecular characteristics of the system, specially in terms of molecular interactions. In the powerful cosolvents of PMMA described in the literature one of the liquid components is always either acetonitrile or an alcohol. These are non-random liquids with a certain degree of order in their structure. Two important characteristics seem to be present in these polymer cosolvent systems die liquid order structure and the tendency of the polymer towards association. The roles of fliese two factors were considered to interpret solvation of PMMA chains in cosolvent systems. " The mechanisms of cosolvent action have been discussed in terms of the competitive interactions between liquid components and one liquid component and the polymer. " The best example is tire case of acetonitrile and a second liquid having a high proportion of methylene units in its molecule, the unfavorable nitrile-methylene interactions between acetonitrile and PMMA favor... 

Let us consider the determination of molecular characteristics S and for butadiene-styrene rubber. As it is known [15], the value of macromolecule diameter square is equal to for polybutadiene - 20.7 and for polystyrene - 69.8 A. Calculating the macromolecule, simulated as cylinder, cross-sectional area for the indicated polymers according to the known geometrical formulae, let us obtain 16.2 A and 54.8 A, respectively. Further, accepting as S for butadiene-styrene rubber mean value of the cited above areas, let us obtain S=35.5 A. Further the characteristic ratio can be determined, which is a polymer chain statistical flexibility indicator [16], with the aid of the following empirical formula [14] ... 

The main molecular characteristics of the 4-arm comb star polystyrene are collected in Table 21.2. The Mw Ri(app)ls ratio, which is related to the volume contraction due to branching is 0.19 for the star comb versus 0.29 for the linear comb of same structure. These very low values agree with the highly branched chain architecture of the comb polymers on which is superposed the volume contraction related to the comb star architecture. The radius of gyration (/ g) and hydrodynamic radius (/ h) of the star comb on the one hand are very close to each other as are and of the corresponding one-branch linear comb polymer. They are equal to 45 nm, in THE at 25 °C for the star comb M = 9 000 000 g/mol) and 25 nm for the similar linear comb (M = 2 700 000 g/mol) in the same conditions. 

Ethylene oxide/styrene block copolymers have been further free-radical copolymerized with other ethylenically unsaturated compounds such as methyl methacrylate and methacrylic acid in benzene, tetrahydrofuran, and dimethylformamide (176). Correlations were made between reactivity ratio and solvent dielectric constant, as well as between solubility parameters of reaction solvent and growing polymer chains with marked effects apparent. Gel permeation chromatography of diblock and triblock copolymers based on polystyrene and poly(ethylene oxide) has revealed interesting molecular characteristics (177). Such block copolymers have an amphiphilic character. In aqueous solution, the polymers form spherical micells with a polystyrene core and a poly(ethylene oxide) outer sheath. The investigations used an aqueous-methanolic solution and were able to ascertain block copolymer structures and to estimate the impurities in the diblock copolymer. 

Table 6.3 Molecular characteristics and glass transition temperatures of eight polystyrenes... 

Table 6.8 Molecular characteristics of four-arm star-branched polystyrenes...

Table 6 Molecular characteristics of the polystyrenes and SI diblock copolymers synthesized for end-functionalization investigated by Zha et al. [55]...

Carbon Cha.in Backbone Polymers. These polymers may be represented by (4) and considered derivatives of polyethylene, where n is the degree of polymeriza tion and R is (an alkyl group or) a functional group hydrogen (polyethylene), methyl (polypropylene), carboxyl (poly(acryhc acid)), chlorine (poly(vinyl chloride)), phenyl (polystyrene) hydroxyl (poly(vinyl alcohol)), ester (poly(vinyl acetate)), nitrile (polyacrylonitrile), vinyl (polybutadiene), etc. The functional groups and the molecular weight of the polymers, control thek properties which vary in hydrophobicity, solubiUty characteristics, glass-transition temperature, and crystallinity. 

Measurements of diffusion of tracer polymers in ordered block copolymer fluids is another potentially informative activity, since molecular diffusion is one of the most basic dynamic characteristics of a molecule. Balsara, et al. have measured the retardation of diffusion due to ordering in the diffusion of polystyrene tracer homopolymers in polystyrene-polyisoprene matrices of various domain sizes [167]. Measurement of the tracer diffusion of block copolymer molecules will also be important. Several interesting issues are directly addressable via measurements... 

Materials. Four samples of sodium poly(styrenesulfonate) (NaPSS) prepared by sulfonation of polystyrenes with narrow molecular weight distribution were purchased from Pressure Chemical Co. The characteristics of the samples, according to the manufacturer, are listed in Table I. The intrinsic viscosities of NaPSS in aqueous NaCl solution were measured using an Ubbelhode viscometer at 25 °C. 

Molecular Weight Characteristics and Quiescent Adsorption at the 0-Condition of the Polystyrene Samples... 

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