Propeller polymers

T. D. Wilson, New SolidBocket Propellant Polymer Binder Materiels, CPTR 87—42, Aug. 1987. 

Lubricants, coolants, propellants, polymers, solvents, drugs... 

Zhou J, Yu H et al (2003) Research progress on synthesis of the polyglycidyl ether nitrate. Chem Propellants Polym Mater 1(6) 9-12... 

Wang B, Zheng Y et al (2013) Synthesis, structural characterization and performance evaluation of nitrated hydroxyl-terminated polybutadiene. Chem Propellants Polym Mater 11 (4) 76-78... 

Ma H, Ma Y, Feng X et al (2011) Research progress in geminal dinitro plasticizers. Chem Propellants Polym Mater 9(5) 39-43... 

Sun Y, Zhou J (2003) Advance in research of energetic plasticizers. Chem Propellants Polym Mater l(5) 20-25... 

Qiang W, Xie H, Yuan W et al (2004) Research progress of green nitration in synthesis of nitric esters. Chem Propellants Polym Mater 2(3) 5-10... 

The propeller polymer (R)-54 bears the similar structural feature of 56 which may lead to interesting NLO property. The work of Persoons and co-workers [55] shows that the chirality of materials can also contribute significantly to the second-order NLO effect. Because of the potentially useful optical and electrical properties and the exciting structures, we have synthesized and characterized (R)-54 and other propeller polymers of similar structure. 

The propeller polymer R)-54 is synthesized by the polymerization of (/ )-32 with l,2-dibromo-4,5-dinitrobenzene, 57, in the presence of Pd(PPh3)4/CuI catalysts. This reaction proceeds at room temperature in a triethylamine-THF solution (Scheme 21). GPC analysis of (iR)-54 shows = 18,000 and M = 12,000 (PDI = 1.5). The two bromine atoms in 57 are highly activated by the two para nitro groups, so the polymerization can take place under very mild conditions. (R)-54 is soluble in chloroform, methylene chloride, and THF. Its specific optical rotation is... 

B. Propeller Polymer with Fluorine Electron Acceptors... 

C. Propeller Polymer of More Extended tt System in the Repeat Unit... 

D. Propeller Polymer Prepared by the Suzuki Coupling Reaction... 

E. Propeller Polymer Prepared from m-Dibromophenylene Linker... 

In the preceding sections, we have shown the preparation of the novel propeller polymers from the o-pheynylene linkers. w-Phenylene molecules are also used to synthesize similar multipolar chiral materials in our laboratory. In the presence of... 

SCHEME 23 Synthesis of (/ )-61, a propeller polymer containing fluorine acceptors. 

SCHEME 24 A propeller polymer with more extended tt system in its dipole unit. 

SCHEME 25 The Suzuki coupling to synthesize the propeller polymer (/ )-63. 

The coupling of 64 with two equivalents of 66 generates 68 as the repeat unit of (R)-6S. The IR spectrum of 68 displays a strong absorption at 2202 cm almost identical to that of (R)-65. Maximum absorptions at = 244, 282, 354, and 430 nm are observed in the UV spectrum of 68. There is a slight red shift ( 12 nm) from the repeat unit 68 to the polymer (/ )-65, indicating a very small conjugation across the l.l -bonds of the binaphthyl units in the polymer. Table 6 summarizes the UV spectral data for the propeller polymers and the repeat units. 

The CD spectra of the propeller polymers (R)-54, (R)-61, (R)-62, (R)-63, and (R)-6S are shown in Figs. 6 and 7. All of these polymers show similar Cotton effects at the short wavelengths due to the chiral binaphthyl units. The major differences are in the long-wavelength region because of the different conjugation in their repeat units. 

TABLE 6 UV-vis Absorption Wavelengths of the Propeller Polymers and the Repeat Units... 

All of the propeller polymers give similar TGA data. They all lose alkyl groups at temperatures between 300 and 400 C. After that, these materials become much more stable. The nitro group-containing polymers probably slowly lose their nitro groups from 400 up to 800°C. 

Another example of a time dependent Mullins Effect is that of a cross-linked polymer, with little or no time dependency when unfilled, which becomes significantly time dependent when filled [42], as shown in Figure 3.2. The more filler incorporated into the system, the more marked the time effect. Many propellant polymers fall into this category and nearly all propellants show time dependence over such long times that true equilibrium data cannot be obtained. This time dependence in the composite material and no time dependence in the unfilled pol3rmer cannot be... 

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