Macromolecules polystyrene

The assumption of forces of interaction between solvent and solute led to the century old principle that like dissolves like . In many cases the presence of similar functional groups in the molecules suffices. This rule of thumb has only limited validity since there are many examples of solutions of chemically dissimilar compounds. For example, for small molecules methanol and benzene, water and N,N-dimethylformamide, aniline and diethyl ether, and for macromolecules, polystyrene and chloroform, are completely miscible at room temperature. On the other hand, insolubility can occur in spite of similarity of the two partners. Thus, polyvinylal-cohol does not dissolve in ethanol, acetyl cellulose is insoluble in ethyl acetate, and polyacrylonitrile in acrylonitrile [12], Between these two extremes there is a whole range of possibilities where the two materials dissolve each other to a limited extent. 

Finally, some termination step occurs, two of which are shown in the scheme. The most common is coupling, in which two radicals combine, leading to one larger macromolecule. Polystyrene radicals typically undergo termination by coupling. Another reaction that is common with some monomers (e.g., methyl methacrylate) is called disproportionation in which on the reaction of two radicals, a hydrogen atom transfers from one species to the other. 

Macromolecule Polystyrene Polyvinyl acetate Polyethylene Acrylic polymers Polybutadiene... 

Therefore (Si/b) should be linearly proportional to AT" tbis behavior has been verified experimentally. See, for example, the behavior of (Si/b) for the macromolecule polystyrene of molecular weight 51000 in the solvent ethylbenzene in Gmsbka et al. (1973). If we can assume a certain type of dependence of D on tbe molecular weight of the polymer (e.g. r oc Jwf (see relations 3.3.90d-f) therefore, from the Stokes-Einstein relation (3.3.90c)... 

Robyr P, Gan Z and Suter U W 1998 Conformation of raoemo and meso dyads in glassy polystyrenes from C polarization-transfer NMR Macromolecules 31 8918- 23... 

Stouffer J M and McCarthy T J 1988 Polymer monolayers prepared by the spontaneous adsorption of sulphur-functionalized polystyrene on gold surfaces Macromolecules 2 1204-8... 

Albertsson (Paiiition of Cell Paiiicle.s and Macromolecules, 3d ed., Wiley, New York, 1986) has extensively used particle distribution to fractionate mixtures of biological products. In order to demonstrate the versatility of particle distribution, he has cited the example shown in Table 22-14. The feed mixture consisted of polystyrene particles, red blood cells, starch, and cellulose. Liquid-liquid particle distribution has also been studied by using mineral-matter particles (average diameter = 5.5 Im) extracted from a coal liquid as the solid in a xylene-water system [Prudich and Heniy, Am. Inst. Chem. Eng. J., 24(5), 788 (1978)]. By using surface-active agents in order to enhance the water wettability of the solid particles, recoveries of better than 95 percent of the particles to the water phase were obsei ved. All particles remained in the xylene when no surfactant was added. 

D. S. Cannel, F. Rondelez. Diffusion of polystyrene through microporous membranes. Macromolecules 75 1599-1602, 1980. 

H. Kim, T. Chang, J. M. Yohanan, L. Wang, H. Yu. Polymer diffusion in linear matrices Polystyrene in toluene. Macromolecules 19 2121-21AA, 1986. 

N. Nemoto, M. Kishine, T. Inoue, T. Osaki. Tracer diffusion of linear polystyrene in entanglement networks. Macromolecules 22 659-664, 1990. 

N. A. Rotstein, T. P. Lodge. Tracer diffusion of linear polystyrenes in poly-(vinyl methyl ether) gels. Macromolecules 25.T 316-1325, 1992. 

A very similar effect of the surface concentration on the conformation of adsorbed macromolecules was observed by Cohen Stuart et al. [25] who studied the diffusion of the polystyrene latex particles in aqueous solutions of PEO by photon-correlation spectroscopy. The thickness of the hydrodynamic layer 8 (nm) calculated from the loss of the particle diffusivity was low at low coverage but showed a steep increase as the adsorbed amount exceeded a certain threshold. Concretely, 8 increased from 40 to 170 nm when the surface concentration of PEO rose from 1.0 to 1.5 mg/m2. This character of the dependence is consistent with the calculations made by the authors [25] according to the theory developed by Scheutjens and Fleer [10,12] which predicts a similar variation of the hydrodynamic layer thickness of adsorbed polymer with coverage. The dominant contribution to this thickness comes from long tails which extend far into the solution. 

If the swelling effects in the polymeric phase are considered, the evaluation of the adsorbed macromolecules as a monolayer seems to be too approximate. The mean-square end-to-end distance of the polystyrene coil (M = 10000) in... 

Xenidou M. and Hadjichristidis N., Synthesis of model nultigraft copolymers of butadiene with randomly placed single and double polystyrene branches. Macromolecules, 31, 5690, 1998. 

Itarou H., Mays I.W., and Hadjichri-Stidis N., Regular comb polystyrene and graft polyisoprene/ polystyrene copolymers with double branches ( Centipedes ). Quality of (l,3-phenylene)bis(3-methyl-l-phenylpentylidene)dilithium initiator in the presence of polar additives. Macromolecules, 31,6697, 1998. 

LeiblerL., Theory of microphase separation in block copolymers. Macromolecules, 13, 1602, 1980. Eoerster S., Khandpur A.K., Zhao J., Bates E.S., Hamley I.W., Ryan A.J., and Bras W. Complex phase behavior of polyisoprene-polystyrene diblock copolymers near the order-disorder transition. Macromolecules, 21, 6922, 1994. 

Inoue T., Soen T., Hashimoto T., and Kawai, H. Studies on domain formation of the A-B t3fpe block copolymer with polystyrene and polyisoprene. Macromolecules, 13, 87, 1970. 

Winter, H.H. Evolution of rheology during chemical gelation. Prog. Colloid Polym. Scl,15,104—110,1987. Hempenius, M.A. et al. Melt rheology of arborescent graft polystyrenes. Macromolecules, 31, 2299, 1998. 

Kathawalla, lA Anderson, JL Lindsey, JS, Hindered Diffusion of Porphyrins and Short-Chain Polystyrene in Small Pores, Macromolecules 22, 1215, 1989. 

Radko, SP Chrambach, A, Electrophoretic Migration of Submicron Polystyrene Latex Spheres in Solutions of Linear Polyacrylamide, Macromolecules 32, 2617, 1999. 

Brulet, A., Boue, F., Menelle, A. and Cotton, J. P. (2000) Conformation of polystyrene chain in ultrathin films obtained by spin coating. Macromolecules, 33, 997-1001. 

Shuto, K., Oishi, Y, Kajiyama, T. and Han, C. C. (1993) Aggregation structure of a two-dimensional ultrathin polystyrene film prepared by the water casting method. Macromolecules, 26, 6589-6594. 

Gong, Y., Huang, H., Hu, Z., Chen, Y, Chen, D Wang, Z. and He, X. (2006) Inverted to normal phase transition in solution-cast polystyrene-poly(methyl methacrylate) block copolymer thin films. Macromolecules, 39, 3369-3376. 

For concentrated polystyrene solutions (c>c ) in n-butylbenzene, Graessley and co-workers [36] observed that the shift factor hconc depends on the number of entanglements per macromolecule E. 

Stafford, C.M., Russell, T.P, and McCarthy T.J., Expansion of polystyrene using supercritical carbon dioxide, effects of molecular weight, polydispersity, and low molecular weight components, Macromolecules, 32, 7610, 1999. 

Guerra, G. Vitagliano, V. M. De Rosa, C. Corradini, P., Polymorphism in melt crystallized syndiotactic polystyrene samples, Macromolecules 1990, 23, 1539 1544... 

---