POLY-P-METHYLSTYRENE

It is typical, for instance, of syndiotactic polystyrene (s-PS) [7-9] and syndiotactic poly- p-methylstyrene (s-PPMS) [10] to present crystalline forms with a transplant conformation of the chains (shown for s-PS in Fig. 1) as well as crystalline forms with sequences of dihedral angles of the kind TTG+G+ (or the equivalent G G TT), corresponding to a s(2/l)2 helical symmetry of the chains (shown for s-PS in Fig. 1). 

Fig. 6. Hydrogen depth profile of a thin film of poly(p-methylstyrene)(H)/ PS(D) diblock copolymer, PMS(H)-b-PS(D), on a silicon wafer as obtained by the l5N-NRA technique [57]. The sample has been annealed for 1 h at 140 °C. PMS(H) is largely enriched at the surface. The solid line is a guide to the eye...

Morphology of the anionically synthesized triblock copolymers of polyfp-methyl-styrene) and PDMS and their derivatives obtained by the selective chlorination of the hard segments were investigated by TEM 146). Samples with low PDMS content (12%) showed spherical domains of PDMS in a poly(p-methylstyrene) matrix. Samples with nearly equimolar composition showed a continuous lamellar morphology. In both cases the domain structure was very fine, indicating sharp interfaces. Domain sizes were estimated to be of the order of 50-300 A. 

Tsunogae Y. and Kennedy J.P., Thermoplastic elastomers by sequential monomer addition. VI. Poly(p-methylstyrene-b-isobutylene-b-/7-methylstyrene), Polym. Bull., 31, 1436, 1993. 

Mesomorphic forms characterized by conformationally ordered polymer chains packed in lattices with different kinds of lateral disorder have been described for various isotactic and syndiotactic polymers. For instance, for iPP,706 sPP,201 sPS,202 syndiotactic poly(p-methylstyrene) (sPPMS),203 and syndiotactic poly(m -methylstyrene),204 mesomorphic forms have been found. In all of these cases the X-ray fiber diffraction patterns show diffraction confined in well-defined layer lines, indicating order in the conformation of the chains, but broad reflections and diffuse haloes on the equator and on the other layer lines, indicating the presence of disorder in the arrangement of the chain axes as well as the absence of long-range lateral correlations between the chains. 

Even if MIP and BET are widely accepted regarding the characterization of HPLC stationary phases, they are only applicable to the samples in the dry state. In order to investigate the impact of polymerization time on the porous properties of wet monolithic columns, ISEC measurements of 200 jm I.D. poly(p-methylstyrene-co-l,2-bis(vinylphenyl)ethane) (MS/BVPE) capillary columns (prepared using a total polymerization time ranging from 45 min to 24 h) have been additionally evaluated (see Table 1.2 for a summary of determined e values). On a stepwise decrease in the time down to 45 min, the total porosity (St) is systematically increasing to about 30% in total (62.8% for 24 h and 97.2% for 45 min). This is caused by a simultaneous increase in the fraction of interparticulate porosity (e. ) as well as the fraction of pores (Cp). The ISEC measurements are in agreement with those of the MIP as well as BET analyses, as an increase in should be reflected in an increase in 8p and as the relative increase in the total porosity (caused by decreasing the polymerization time... 

S. Nozakura, T. Kitazawa, Y. Yasuhara, and S. Murahashi Infrared absorption bands possibly associated with the helical structure of polystyrene, poly-p-methylstyrene, and poly-m-methylstyrene prepared with Ziegler catalyst. Bull. chem. Soc. Japan 32, 313—314 (1959). 

The bilayer morphology of thin asymmetric films of may be unstable. A regularly corrugated surface structure of the films was ascribed to spinodal transition into a laterally phase separated structure, where the surface morphology depended on the polymer incompatibility and the interfacial interactions [347, 348]. Recently, the phase separation and dewetting of thin films of a weakly incompatible blend of deuterated PS and poly(p-methylstyrene) have been monitored by SFM [349, 350]. Starting from a bilayer structure, after 454 h at T= 154 °C the film came to the final dewetting state where mesoscopic drops of... 

Poly(pMeSt-b-IB-b-pMeSt) Poly(p-methylstyrene- block- isobutylene- block-... 

The affect of polymer stereoregularity in the chains on the PAL data has also been studied. Hamielec et al [56] found what appears to be an increased lifetime (hole size) with increased randomness of the chain configuration in a series of polyvinlychloride (PVC) polymers, despite the large degree of scatter in the sample (probably due to the fact that a series of commercially available products were used.). They however found little correlation with tacticity in polypropylene. More recently a PAL study on a series of very well characterized polystyrene and poly(p-methlystyrene) samples of differing tacticity [57] was performed. In addition to finding that the polystyrene samples have smaller free volume holes than the poly(p-methylstyrene) samples, they found that the syndiotactic samples had broader hole distributions than the attactic samples. 

PPG PPGDE PPMA PpMOS PpMS polylpropylene glycol) polylpropylene glycol dimethyl ether) polyin-propyl methacrylate) poly(p-methoxystyrene) poly(p-methylstyrene)... 

A comparison of monolithic conventional size, microbore, and capillary poly(p-methylstyrene-co-l,2-bis(p-vinylphenyl)ethane) columns confirmed that the efficiency for analysing proteins and oligonucleotides improved with decreasing column internal diameter, even if monolithic capillary columns up to 0.53 mm internal diameter were successfully used for the fractionation of the whole spectrum of biopolymers including proteins, peptides, and oligonucleotides as well as double-stranded DNA fragments under IPC conditions [14,23]. 

Trojer, L. et al. Monohthic poly(p-methylstyrene-co-l,2-bis(p-vinylphenyl)ethane) capillary columns as novel styrene stationary phases for biopolymer separation. J. Chromatogr. A. 2006, 1117, 56-66. 

Figure 8 gives results of some copolymerization studies, namely, the addition of styrene to living a-methylstyrene tetramer and the addition of styrene to living poly(p-methylstyrene). Table III gives the propagation rate constants of some homopolymerizations and copolymerizations and the discussion of these values is interesting. 

Diundecyl phthalate is FDA approved for use as a component of poly (p-methylstyrene) and rubber-modified poly (p-meth-ylstyrene) intended for use in contact with food, subject to 21CFR177.1635. 

Chung, T.C. Lu, H.L. Ding, R.D. Synthesis of polyethylene-g-polystyrene and polyethylene-g-poly(p-methylstyrene) copolymers. Macromolecules 1997, 30, 1272. 

Degradation in the presence of solvents has also been applied to the conversion of other styrenic polymers, such as poly(p-methylstyrene) and poly(styrene-allyl alcohol).64,65 Figure 4.11 shows the temperature dependence of the conversion of poly(p-methylstyrene) when using phenol, 1-methyl-naphthalene and tetralin as solvents. In this case, tetralin leads to the greatest degradation below 370 °C, whereas the order is reversed above that temperature. These results indicate that the effect of the solvent in the degradation of styrenic polymers is strongly influenced by the temperature. 

Figure 4.11 Temperature dependence of the poly (p-methylstyrene) conversion in the presence of different solvents 64 A phenol, 1-methylnaphthalene, O tetra-lin.

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