Polystyrene poly-a-methyl

Research in this area has resulted in the preparation of several comb polymers (Halasa, 1974 Folket al., 1044). The metallation technique is a useful and versatile method as it can be used with any polymeric material that contains a few double bonds. For example, ethylene-propylene was successfully grafted with norbornene. Similar reactions were performed on polymeric materials that contain aromatic rings, such as polystyrene, poly-a-methyl styrene, and polyphenylene oxide (PPO). 

In contrast to polystyrene, poly(a-methyl styrene) yields in vacuum pyrolyses at temperatures between 200 and 500°C 95-100% monomer. By comparison, polystyrene only yields about 40.6% [457]. The difference can be attributed to the fact that hydrogen transfer is completely blocked from the sites of chain scission by the methyl groups in the a-positions [457]. As a result, the terminal free-radicals unzip into monomers and dimers. 

SAE Saeki, S., Narita, Y., Tsubokawa, M., and Yamaguchi, T., Phase separation temperatirres in the polystyrene-poly(a-methyl styrene)-metltylcyclohexane system. Polymer, 24, 1631, 1983. 

Examples shown in this chapter are for PMMA. Other polymers can be separated as well. The polymers separated so far (1,2) include polystyrene, poly(a-methylstyrene), polycaprolactone, polycarbonate, poly(hexyl isocyanate), polytetrahydrofuran, poly (vinyl methyl ether), and polyvinylpyrrolidone. 

This method was first applied by McCormick27 and by Bywater and Worsfold11 to the system a-methylstyrene/poly-a-methyl-styrene, and the free energy, entropy and heat of polymerization as well as the ceiling temperature were determined. Similar studies concerned with the system styrene/polystyrene are being carried out in our laboratories. 

Figure 10.7 The phase diagram (a) and the glass transition temperatures (b) of a PSC/PVME mixture obtained, respectively, by light scattering and differential scanning calorimetry (DSC). Irradiation experiments were performed in the miscible region at 127 C indicated by (X) in the figure of trans-cinnamic acid-labeled polystyrene/poly(vinyl methyl ether) blends.

Various techniques have been used for the determination of oligomers, including GC [135], HPLC [136-138], TLC for polystyrene and poly a-methyl-styrene [139] and SEC for polyesters [140,141]. GC and PyGC-MS can also profitably be used for the analysis of the compositions of volatile products formed using different flame retardants (FRs). Takeda [142] reported that volumes and compositions of the volatile products and morphology of the char were affected by FRs, polymers (PC, PPE, PBT) and their reactions from 300... 

Figure 1. Morphology of sequential IPNs. (a) Crois-poly (ethyl acrylate)-m/er-crojs-polystyrene, showing typical cellular structure and a fine structure within the cell walls, (b) Cross-poly (ethyl acrylate)-/ /cr-cross-polystyrene-s/a/-(methyl methacrylate), showing smaller domain structure. PEA structure stained with OsO. (Reproduced from ref. 5. Copyright 1972 American Chemical Society.)...

Sugawara et al. (91,92) have extended their work on chloromethylated polystyrene to chloromethylated poly(a-methylstyrene). Poly(a-methyl styrene)... 

The values of Mc [defined by Eq.(5.19)] are those reported by Ferry (15) and Berry and Fox (16), except that for polystyrene (124) and the values in parentheses for poly-methyl methacrylate (146), polybutadiene (79,197), and ds-polyisoprene (79, 197). The values of (defined as described in 5.4.1) are from the same compilations, except that for poly (a-methyl styrene) (161). The values of Mc were obtained as described in Section 5.4.4. 

Fig. 8.9. Power law exponent d as a function of the coil overlap parameter c[ ] at low concentrations. The filled circles are narrow distribution polystyrene solutions (1 77, 316, 318), the open circles are poly(a-methyl styrene) (198, 318). Solvents are chlorinated di-phenyls except the intrinsic viscosity data which were obtained in toluene. Symbols are for polystyrene M= 13.6 x 106, 4 1-8 x 10 , and 0.86 x 106 for poly(a-methyl styrene) O M = 7.5 x 10 , 6 3.3 xlO6, Cr 1.82 xlO6, O- 1.14x10 , a. 0.694x10 , and...

Judged by the superposability of viscosity-shear rate data on the same master curve for a variety of polymers [polystyrene (155) (Fig. 8.10), poly(a-methyl... 

Fig. 8.12. Dimensionless shear rate /30 locating the onset of shear dependence in the viscosity for narrow distribution poly(a-methyl styrene) systems. Symbols are (198, 199) O M = 3.3 x 106, 6 M=1.82x 106,O-M= 1.19 x 106, and 9 M = 0.444 x 106. Values for intrinsic viscosity (cM=0) are similar to those for polystyrene (see caption of Fig. 8.11)...

Osaki, K., SchragJ.L. Viscoelastic properties of polymer solutions in high-viscosity solvents and limiting high-frequency behavior. I. Polystyrene and poly(a-methyl-styrene). Polymer J. (Japan) 2,541-549 (1971). 

Some grafting between polystyrene and polyethylene may occur, but we think not. Substantial amounts of polystyrene (but not all) have been extracted from the blend samples by soaking the specimens in refluxing THF for several days. We suspect that if grafting does occur, it is not a significant contributor to polystyrene mass uptake. All the polystyrene could be extracted from a 50 wt % polystyrene/poly(4-methyl-l-pentene) (PMP) blend that was prepared by essentially the same procedure. The backbone of PMP (with two tertiary C —H bonds per repeat unit) is likely more susceptible to radical grafting than HDPE. 

Random chain cleavage followed by chain unzipping is characterized by high monomer yields and a slow decrease in the molecular weight of the polymer, for example, exhibited by PMMA, poly(a-methyl styrene), polystyrene polytetrafluoroethylene. 

The study by low-angle X-ray diffraction and electron microscopy of concentrated solutions of the copolymers in preferential solvents for polybutadiene (iso-prene, butadiene) or for poly(a-methyl styrene) (styrene, a-methylstyrene, methyl methacrylate, methylethyl ketone) and of copolymers in the dry state obtained by slow evaporation of the solvent from the mesophases have shown the existence of three types of structure hexagonal, lamellar, and inverse hexagonal depending upon the copolymer composition84,85. The factors governing the structural type and the structural parameters are the same as in the case of polystyrene-polybutadiene copolymers85. ... 

Block copolymers of butadiene and vinyl-2-naphtalene (BVN) have been synthetized and studied by the same techniques as polybutadiene-poly(a-methyl styrene) and polystyrene-polybutadiene block copolymers86,87. They exhibit the same structures, namely lamellar and cylindrical as SB and BMS block copolymers86,87. ... 

FIG. 16.17 Power law exponent — ft — 1 — n as a function of the coil overlap parameter c[ 7], for solutions of polystyrene (filled symbols) and poly(a-methyl styrene) in chlorinated biphenyls (open symbols). The values of [77] were obtained in toluene. Molecular weights range from 860 to 13,600 kg/mol for polystyrene and from 440 to 7500 kg/mol for poly(a-methyl styrene). From Graessley (1974). Courtesy Springer Verlag. 

Chen and Gardella used this surface engineering strategy to create siloxane-rich surfaces [40]. Their approach involved the blending of a homopolymer (A) with a block copolymer composed of a block with the same chemical identity as the homopolymer (A) and a block of PDMS. For all homopolymer types studied (polystyrene, poly(cc methyl.styrene) and Bisphenol A polycarbonate), XPS analysis of Si C ratios revealed a significant enrichment of the PDMS... 

Robard, A. Patterson, D., "Temperature Dependence of Polystyrene-Poly(vinyl methyl ether) Compatibility in Trichloroethane," Macromolecules, 10, 1021 (1977). 

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