Phenyl groups polystyrene

Consider a vinyl polymer in solution. This polymer contains only one substituted hydrogen on each monomer and has a structure which looks like —CHs—CHK—CH2CHK—CHj—CHS— , where R may be a phenyl group (polystyrene), or a methyl group (polyisopropylene), or some other substituent. 

A still more intricate pattern of potential energy may be expected if the repeat units of the polymer chain carry other substituents, such as the phenyl groups in polystyrene, but these examples establish the general method for quantitatively describing the effects of steric hindrance on rotation. 

In the methacrylate homologous series, the effect of side-chain bulkiness is just the opposite. In this case, however, the pendant groups are flexible and offer less of an obstacle to free rotation than the phenyl group in polystyrene. As chain bulk increases, molecules are wedged apart by these substituents, free volume increases, and Tg decreases. 

The anion-selective (AX) membranes (Eig. 2b) also consist of cross-linked polystyrene but have positively charged quaternary ammonium groups chemically bonded to most of the phenyl groups in the polystyrene instead of the negatively charged sulfonates. In this case the counterions are negatively... 

Being a hydrocarbon with a solubility parameter of 18.6MPa - it is dissolved by a number of hydrocarbons with similar solubility parameters, such as benzene and toluene. The presence of a benzene ring results in polystyrene having greater reactivity than polyethylene. Characteristic reactions of a phenyl group such as chlorination, hydrogenation, nitration and sulphonation can all be performed with... 

The butyrate substituents are larger than those for other polymers listed, but they are not proportionately larger than the exceptional length of the structural unit of cellulose. An inspection of models shows that the three butyrate units can be accommodated about the cellulose ring with less obstruction than for the phenyl groups of polystyrene, for example. 

The majority of commercial polystyrene molecules consist of a backbone of carbon atoms with phenyl groups attached to half of the carbon atoms, as shown in Fig. 21.1. Free radical initiator residues terminate each end of the chain. Minor variants include chains terminated by anionic or cationic initiator residues. All commercial polystyrene products are atactic that is, the placement of the phenyl groups on either side of the chain is essentially random, as illustrated in Fig. 21.2. 

A substantial intramolecular protective effect by phenyl groups in polymers is shown by the low G values for Hz and crosslinking in polystyrene (substituent phenyl) and in polyarylene sulfones (backbone phenyl), as well as many other aromatic polymers. The relative radiation resistance of different aromatic groups in polymers has not been extensively studied, but appears to be similar, except that biphenyl provides increased protection. Studies on various poly(amino acid)s indicate that the phenol group is particularly radiation resistant. 

The combination of radiation-sensitive and radiation-resistant groups is interesting. Halogen substitution of the phenyl group in polystyrene results in high radiation sensitivity with inter-molecular crosslinking. 

Spoly(vinylbenzylchloride). -Cross-linked using divinylbenzene. Chloromethylated, cross-linked polystyrene resins were obtained coiranercielly from Bio-Rad Laboratories. Percent chloromethylation js based on the available phenyl groups in the polymer that is minus the percent cross-linking. =D=dioxane E ethanol. Percent of available chloromethyl croups reacted with donor. —Percent reaction x percent chloromethylation. Polymer prepared by free-radical polymerization of 60.00 para-neta chloromethylated sytrene (Dow Chemical). Reaction heated at 50-55°C. 

A polystyrene with polymethacrylate grafts on some of the phenyl groups ... 

Following the initial observation113 of excimer fluorescence from dissolved polystyrene, Hirayama114 has reported a systematic survey of the fluorescence spectra of the di- and triphenylalkanes shown in Figure 14. In addition to the normal molecular spectrum of the phenyl group exhibited by all the molecules listed, an excimer band is exhibited by those systems in which the planar phenyl groups are separated by exactly three carbon atoms or a distance of 2.54 A in the trans propane chain. Since there is no evidence of a... 

To expedite peptide syntheses of up to 124 amino acid units, beads of solid polystyrene— with chloromethyl groups, —CH CI, para to about every hundredth phenyl group—are used in an automated process. The sequence of steps is (1) attach C-terminal Boc-protected amino acid by... 

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