Phenyl-modified poly

Phenyl and vinyl modified versions of poly(m-carborane-siloxane) were readily prepared using the procedure just described, by introducing the appropriate silane feed into the reaction mix.19 Typically, 1 to 3 mol % di-chloro-methylvinylsilane was added to the di-chlorosilane feed in the syntheses described earlier. The repeat unit of the phenyl modified poly(w-carborane-siloxane) is shown in 5. 

Figure 1 Solution-state NMR spectra of the CD2C12 soluble fraction of phenyl modified poly (7 -carboranyl-si Ioxane ) rubber, (a) nB and 11 B 1111 NMR (b) 111 and 1H[11B] NMR. 

Table 2 Limulus Activity of Phenyl-Modified Poly(MA-CDA)s with Different Molecular Weight Backbones...

In regard to substitution reactions of the functional phenyl groups, poly(diphenylsilylene-co-methylene) is a very interesting educt for the preparation of modified polycarbosilanes as precvirsors for SiC-based ceramic fibers. 

Figure 4. E -modulus (GPa) as a function of draw ratio for 20 mol% p-hydraxy benzoic acid modified poly(phenyl-l,4-phenylene terephthalate) (not listed in tables) fibers. Spinning temp. = 320°C.

An attempt was also made to modify poly(vinylphenol) with vinyl phenyl ether under similar conditions described above. However, it was found that a significant amount of phenolic groups remained unreacted after a week of the reaction as indicated by free OH absorption in its FT-IR spectrum. 

Very low asymmetric induction (e.e. 0.3-2.5%) was noted when unsymmetrical sulphides were electrochemically oxidized on an anode modified by treatment with (— )camphoric anhydride or (S)-phenylalanine methyl ester299. Much better results were obtained with the poly(L-valine) coated platinum electrodes300. For example, t-butyl phenyl sulphide was converted to the corresponding sulphoxide with e.e. as high as 93%, when electrode coated with polypyrrole and poly(L-valine) was used. 

Selection of appropriate conditions to modify polymers is facilitated by preliminary studies with well designed model compounds. The work with model systems is critical when studying condensation polymers because the main chain linkages have proved to be remarkably labile under certain conditions. Condensation of 4-chlorophenyl phenyl sulfone with the disodium salt of blsphenol-A yields 2,2-bis[4 -(4"-phenylsulfonylphenoxyl)phenyl] propane, T, an excellent model for the poly(arylene ether sulfone) substrate. Conditions for quantitative bromination, nitration, chloro-methylation, and aminomethylation of the model compound were established. Comparable conditions were employed to modify the corresponding polymers. 

Polymers containing pendant carbamate functional groups can be prepared by the reaction of phenyl isocyanate with poly(vinyl alcohol) in homogeneous dimethylsulfoxide solutions using a tri-ethylamine catalyst. These modified polymers are soluble in dimethyl sulfoxide, dimethylacetamide, dimethylformamide and formic acid but are insoluble in water, methanol and xylene. Above about 50% degree of substitution, the polymers are also soluble in acetic acid and butyrolactone. The modified polymers contain aromatic, C = 0, NH and CN bands in the infrared and show a diminished OH absorption. Similar results were noted in the NMR spectroscopy. These modified polymers show a lower specific and intrinsic viscosity in DMSO solutions than does the unmodified poly(vinyl alcohol) and this viscosity decreases as the degree of substitution increases. 

In an enantiomer-differentiating oxidation at a poly-(L-valine)-coated Pb02 anode, rac-2,2-dimethyl-l -phenyl-1 -propanol was partially oxidized leaving 43% optically pure (5)-alcohol [371]. At a TEMPO-modified graphite felt anode rac-1-phenyl-ethanol has been enantioselectively oxidized in the presence of (-[-sparteine leaving 46% of the (/ [-alcohol with 99.6% ee [372]. However, under the same conditions, an exclusive dehydrogenation of (-[-sparteine to the iminium salt without oxidation of the alcohol was found [373]. 

Poly[(i )-2-bromo-5-(tributylstannyl)-3-l4-(4-ethyl-2-oxazolin-2-yl)-phenyl]thiophene [Polymerization of (i )-2-bromo-5-(tributylstannyl)-3-[4-(4-ethyl-2-oxazolin-2-yl)phenyl]thiophene (EOPT-Br,Sn) with Pd2(dba)3 as a catalyst, the CuO-modified Stille-McCullough method] [74]. 

Naito and Kanemitsu (1996) investigated the relationship between the prefactor mobilities, zero-field mobilities, and the glass transition temperatures of OX doped polyarylate (PA), PC, poly(methyl methacrylate) (PMMA), PS, poly(vinyl chloride) (PVC), polyethylene terephthalate) (PET), and poly(vinyl butyral) (PVB), DEH doped PC, 5(p-diethylaminophenyl)-l-phenyl-3-(/ -diethylaminostyryl)-2-pyrazoline (DEASP) doped PS, and DEASP doped PC. OX, DEH, and DEASP are highly polar molecules with similar dipole moments. By modifying the polymer, the glass transition temperature can be varied over... 

Reactivity with Diazo Oxides and Azides. Diazo oxides, e.g. 2,6-di-f0rf-butyl-4-diazo-2,5-cyclohexadiene-l-one (184, R = terr-butyl) or 2,6-diphenyl-4-diazo-2,5-cyclohexadiene-l-one (184, R = phenyl) are thermolabile and photolabile. Car-benes 185 are formed from 184 as reactive intermediates. The process proceeds in a one-step mechanism in which the carbene species reacts in the singlet state [238], The attachement of 185 to saturated hydrocarbon chains proceeds via insertion in C—H bond during processing. LDPE and PP were modified in this way [239, 240]. Poly(oxymethylene) was modified similarly. 

---