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Notes: Dielectric dispersions of reconstituted collagens and gelatin were measured from 0.1 to 10 kHz and -160 to +160°C. At 0.1 kHz there is a γ transition at -80°C which is attributed to the H2O-coupled local modes. The process has an activation energy of 7.5 kcal. A devitrification process is observed at 10-20°C. Both of these processes have their counterparts in the dynamic mechanical measurements. The tan δ values are up to 3 times as great for the dynamic mechanical dispersions. There is an additional hightemperature dielectric loss transition which does not correspond to any seen with the mechanical experiments. A probable mechanism for this absorption is the Maxwell-Wagner-Sillars effect.

Notes: The physical state of the material obtained during the various stages of preparation of a typical MgCl2-supported, high-mileage propylene polymerization catalyst was studied by BET, mercury porosimetry, and x-ray diffraction techniques. The starting MgCl2 and the substance after HCl treatment have negligible BET surface areas. Mercury porosimetry showed that they have large pores with radii 〉 200 nm which are probably crevices between MgCl2 crystallites. The most pronounced physical changes occur during dry porcelain ball milling in the presence of ethyl benzoate. After 60 h or more of ball milling the material had a 5.1-7.3 m2 g-1 BET surface area, twice the pore surface area, and a smaller pore radius than before ball milling and a large reduction in crystallite sizes to almost ultimate dimensions. The crystallites were probably held together by complexation with ethyl benzoate in the form of large agglomerates. Subsequent reactions with p-cresol and triethyl aluminum had minor effects in further reduction of the MgCl2 crystallite size but efficiently brokeup the agglomerates. The final refluxing with TiCl4 increased the BET surface area to 110-150 m2 g-1 but may have increased the crystallite size somewhat due to cocrystallization of TiCl3 and AlCl3 with MgCl2. There may have been only 8-10 crystallites in each catalyst particle. The surface structure of the catalyst resembled those of the classical Ziegler-Natta γ-TiCl3·0.33 AlCl3 catalyst.

Notes: Pyrolysis of polyacetylene is marked by high yields of proton-enriched products methane, ethane, ethylene, propane, polypylene, butadiene, cyclopentadiene, 1,3-pentadiene, and toluene in total amounts exceeding benzene. The activation energies for their formation are low. Polyacetylene doped with AsF5 and iodine produced these products in even higher yields of two to 17 times of undoped polymers. The dominant mechanism is thought to be random-chain scission followed by electron-proton exchange reactions. Polymethylacetylene is thermally less stable than polyacetylene. Pyrolysis gave mesitylene as the expected main product. However, as in the case of polyacetylene, large amounts of proton-enriched products were formed with moderate activation energies. (The yields of methane, propylene, and propane are nearly the same in the pyrolysis of polymethylacetylene as compared to that of polyacetylene at 923°K referenced to mesitylene and benzene, respectively.) By analogy, mechanisms involving both electron-proton and electron-methyl exchange reactions were proposed to account for the formation of all the pyrolyzates of polymethylacetylene. These reactions, not observed in the pyrolysis of polypropylene and polyisoprene, are attributable to the conjugated backbone permitting facile migrations of electrons, protons, and methyl groups.

Notes: The effect of parasubstituents on the radiation chemistry of poly(α-methylstyrene) (PMS) was compared for the fluoro (PFMS), chloro (PCMS), bromo (PBMS), isopropyl (PiPMS), and methoxy (PMeOM) derivatives. Radiolysis yields, ESR spectra, and GC—MS analysis of products were obtained. PMS and PFMS have similar low radiolysis yields, products, and product distributions. Only main-chain radicals which persist to 200° were observed. PCMS has increased values of Gs, Gx, and Gr. The product analysis results suggest that the presence of chlorine contributes to the primary process by dissociative electron capture and enhances the cleavage of α-methyl group. Irradiation of PBMS caused crosslinking and yielded few volatile products. PMeOMS and PiPMS gel readily by γ-irradiation and may be useful as negative radiation resists.

Notes: More than a hundred propylene polymerizations were carried out with the CW catalyst (our particular MgCl2/ethylbenzoate/p-cresol/AlEt3/TiCl4 supported high mileage catalyst). Highest I.I. index (% yield of boiling heptane insoluble product) of 96.2 ± 0.9 was obtained at [Ti] = 2.4 × 10-4 M, A/T (amount of AlEt3 with 0.33 equivalent of methyl-p-toluate to amount of Ti in the catalyst) = 167 at 50°C. The I.I. values became lower when any one of these variables was changed. The I.I. values did not change with time of polymerization, indicating that both stereospecific and nonstereospecific sites were produced at the same time and polymerized monomers during the course of a polymerization. Estimates of maximum active site concentrations, [Ti*]0,Because of the complexity of the catalyst system, the active sites are designated as follows: [Ti*], active sites of all kinds at a given time; [Ti*]0 active sites of all kinds at time zero; [Ti1*], active sites of the first kind formed initially upon activation; [Ti2], active sites of the second kind, which were transformed from the former, and are responsible for olefin polymerization after the initial phase of rapid decay of activity; [Ti*]i, stereospecific active sites; [Ti*]a, nonstereospecific active sites, and [Ti*]t = [Ti*]i + [Ti*]a Similarly, the subscripts 1 and 2 for the various rate constants refer to active sites Ti1* and Ti2*, respectively. Finally [Ti] is the concentration of total titanium in the amount of catalyst used. [Ti-P] is the titanium polymer bond concentration as determined by 14CO tagging; [Ti-P] (1 h) and [Ti-P] (48 h) are the values obtained with indicated time of contact of 14CO with the polymerization mixture in the obsence of monomer. were obtained from a variation of vn-1 versus t-1. The values of [Ti*]0.i and [Ti*]0,a for the stereospecific and nonstereospecific sites, respectively, are in excellent agreement with those values of [MPB]0 (metal polymer bond concentrations at t = 0) determined earlier by radiotagging with tritiated methanol. The rate of formation of [Ti*]1 (the initial active site) is first order with respect to [Ti] and [A] with an activation energy of 12 kcal mol-1 where [A] is the AlEt3 concentration. The rate constants of propagation at 50°C are kp,i ∼ 160M-1s-1 and kp,a ∼ 11M-1s-1. The activation energy for the stereospecific propagation is about 4.1 kcal mol-1. At 50°C the rate of polymerization decreases according to second order kinetics suggesting bimolecular processes which transform one-half to one-fourth of the Ti1* site to Ti2* types depending upon experimental conditions, while the remainder decay to inactive species. The values of kt1 lie between 19 and 61M-1s-1. These processes are more complicated at 70°C involving two consecutive reactions; at low [A], the data fits better with first order decay kinetics. Comparison of the [Ti2*] values and the values of [Ti-P] obtained by 14CO tagging suggests that CO reacts primarily with the Ti2* sites and very little with the initially formed Ti1* sites. The Ti2* sites are slightly less active than the Ti1* sites having kp2,i ∼ 86M-1s-1 and kp2,a ∼ 7M-1s-1 at 50°C.

Notes: Procedures for the synthesis of polyacetylene ([CH]x) with Mn (number average molecular weight) from 400 to about 106 have been developed. This probably represents the largest range of molecular weight (MW) obtainable for a given monomer by a single initiator system. The catalyst residue level in [CH]x can be significantly reduced by acidic-methanol purification. The very low MW polymer L-[CH]x (polyacetylenes with Mn 400-500), has the same cis crystal structure as the higher MW polymers but is less ordered along the c-axis. It is isomerized to the trans material with apparently a more compact unit cell than high MW polymers. There is annealing of crystallite which increases the longitudinal order during thermal isomerization. This process occurs more readily and with lower activation energy in L-[CH]x than for polymers with higher MW. Isomerization of high MW polymers tends to trap cis units which can result in degradation as evidenced by the formation of sp3 carbon vibrations in IR spectra. This is true even for L-[CH]x after prolonged heating. The results render credence to the proposal based on anamalous resonance Raman scattering profile that there can be very short trans segments in thermally isomerized trans-[CH]x.

Notes: Iodine azide adds to cyclohexene in acetonitrile or 4:1 methylene chloride/acetonitrile to give trans-1-azido-2-iodocyclohexane. In methylene chloride this reaction gives a mixture of the cis-and trans-iodoazides owing to competing radical addition. Iodine azide adds to 1-hexene in acetonitrile by an ionic mechanism to give a 3:1 mixture of the 2-azido-1-azido- and 1-azido-2-iodohexanes. Dehydroiodination of the model iodoazides proceeds smoothly with potassium t-butoxide in diethyl ether or THF in the presence of 5 mol % 18-crown-6 at room temperature, giving in the previous example a mixture of 2-azido- and trans-1-azidohexenes. Polybutadiene, carboxyterminated poly(acrylonitrile-co-butadiene), and hydroxy-terminated polybutadiene gave iodoazide derivatives with up to 96% of the theoretical maximum nitrogen content and strong azide IR absorption. High azidoiodination gave polymer with N3/I ratios slightly higher than unity while low percent azidoiodination led to polymer with N3/I ratios of as low as 2:3. All of the nitrogen introduced was in the form of azide function. Dehydroiodination gave polymers with vinyl azide functionality and caused loss of some of the azide groups. All the azidoiodinated polymers decomposed between 120 and 160°C. The dehydroiodinated materials were less stable, decomposing between 100 and 150°C. The temperature of initial decomposition decreased as azide content increased. Polymers with 〉55-60% of the theoretical maximum azide content were shock sensitive.

Notes: Thermal degradation of polyacetylene has been studied by pyrolysis gas chromatography mass spectrometry (PGC-MS). The most abundant product is benzene, but significant quantities of other products are also produced. In decreasing order of yield, these are methane, ethylene, propylene, ethane, butadiene, toluene, and xylenes. A simple mechanism capable of accounting for most of the observed products is random chain scission followed by electron-proton exchanges and in some cases ring closure. The total material balance between proton-rich and proton-depleted products is within 10%.

Notes: Electron paramagnetic resonance (EPR) was used to study a MgCl2-supported, high-mileage olefin polymerization catalyst. Anhydrous Toho MgCl2 was the starting material. Treatment with HCl at an elevated temperature, ethyl benzoate by ball-milling, p-cresol, AlEt3, and TiCl4produced a catalyst that contained a single EPR observable Ti+3 species A, which was strongly attached to the catalyst surface, had a D3h symmetry, and no other Ti+3 ion in an immediately adjacent site. Species A constitutes only 20% of all the trivalent titaniums; the remainder is EPR-silent and may be attributed to those Ti+3 ions that have adjacent sites occupied by one or more Ti+3 ions. Activation with preformed AlEt3/methyl-p-toluate complexes produced a single Ti+3 species (C) with rhombic symmetry and displaying 27Al superhyperfin splitting which has attributes for a stereospecific active site. This species is unstable under polymerization conditions and is transformed to another species with axial symmetry and solubilization. Both processes could lead to catalyst deactivation and loss of stereospecificity. Catalysts activated by AlEt3 and methyl-p-toluate separately in various sequential orders produced a multitude of EPR-observable Ti+3 species with varying degrees of motional freedom deemed detrimental to stereospecific polymerization of α-olefins.

Notes: Homopolymers of 2,2,2-trifluoroethyl(methacrylate) (TFEMA) and 2,2,2-trichloroethyl-(methacrylate) (TCEMA) and copolymers with methyl-α-chloroacrylate (MCA) in a range of compositions were synthesized. The reactivity ratios were obtained; the two copolymerizations were close to ideal. Poly(MCA) showed Gs = 7.4 and Gs = 0.9 by γ-radiolysis. On the other hand, poly(TFEMA) and poly(TCEMA) and Gs values of 2.0 and 2.4, respectively, and Gx = 0. Radiolysis of copolymers was initiated to a large degree by dissociative electron capture by the halogen atoms in both comonomers, as revealed by the ESR spectra of radicals derived from them. Germinal recombinations in irradiated poly(TFEMA) suggested the presence of radicals in proximity. This process was absent in the copolymers. GC-MS analysis of volatile products and other supporting evidence showed that TFEMA monomers tended to depolymerize; the TCEMA monomers did not. The radiolysis yields varied monotonically with the comonomer composition for the MCA-TFEMA system but the yield-composition relationship was irregular in MCA-TCEMA copolymers. Four noncrosslinking systems are potential radiation resists arranged in increasing order of promise: poly(TFEMA) (Gs = 2.0, Tg = 70°); poly(TCEMA) (Gs = 2.7, Tg = 142°); poly(94MCA-co-6TCEMA) (Gs = 2.7, Tg = 142°); and poly(68MCA-co-32TFEMA) (Gs = 3.0, Tg = 112°). These materials merit further investigation for E-beam or x-ray lithographic applications. Mechanisms of radiolysis for these materials, based on ESR, GC-MS, and radiolysis yield data, were discussed.