Poly PBZT

Few other sets of viscosities exist for polymeric nematics. Yang and Shine (1993) obtained three of the Leslie viscosities for monodomains of poly(n-hexyl isocyanate) (PHIC) from rheological measurements in the presence of an electric field, and they obtained values reasonably consistent with the predictions of the Kuzuu-Doi expressions. From monodomains of the polyion PBZT, poly(l,4-phenylene-2,6-benzobisthiazole) in methane sulfonic acid, some of the Leslie-Ericksen parameters have been extracted via light-scattering and magnetic-field-reorientation studies (Berry 198S Srinivasarao and... 

Figure 1. Molecular structures of poly(p-phenylene-benzothiazole) (PBZT), poly(p-phenylene-benzoxazole) (PBO) and poly(p-phenylene-benzimidazole) (PBI).

F ure 7. Molecular structures of poly[(7-oxo-7,10-ff-benz[de]imidazo 4, 5 5,6]-benzimidazo[2,l-a]isoquinoline-3,4 10,11-tetrayl)-10-carbonyl] (BBL), poly (benzo-[l,2-d 4,5-d ]-bisthiazole-2,6-diyl)-(2,5-dihydroxy-1,4-phenylene) (DiOH-PBZT), poly (benzo-[ 1,2-d 4,5-d ]-bisoxazole-2,6-diyl)-(2,5-dihydroxy-1,4-phenylene) (DiOH-PBO), poly (benzo-[l, 2-d 4,5-d ]-bisimidazole-2,6-diyl)-(2,5-dihydroxy-1,4-phenylene) (DiOH-PBI)... 

ACRONYMS, ALTERNATIVE NAMES PBT, PBZT, poly( p-phenylene-2,6-... 

ACRONYMS, ALTERNATIVE NAMES PBT, PBZT, poly(p-phenylene-2,6-benzobisthiazolediyl), poly[(benzo[l,2-d 4,5-d ]bisthiazole-2,6-diyl)-l,4-phenylene]... 

PBO, PBZ, and PlPD. PBZ, a family ofp-phenylene-heterocyclic rigid-rod and extended chain polymers includes poly(p-phenylene-2,6-benzobisthiazole) [69794-31-6] (trares-PBZT), poly(p-phenylene-2,6-benzobisoxazole) [60871-72-9] (cis-PBO), and poly[2,6-diimadazo[4,5-b 4, 5 -e]pyridinylene-l,4(2,5-... 

Poly(p-phenylene benzobisthiazole) PBZT Poly(p-phenylene terephthalamide) PPTA Poly(p-xylylene) PPX... 

PDA polydiacetylene BMCU butoxycarbonylmethylurathane group PTS para-toluene sulfonate irares-PA irares-polyacetylene PAZ polyazine PI poyimide PQ polyquinoline PPV poly(p-phenylene vinylene) PT poljdhiophene PBZO poly(p-phenylene benzobisoxazole) PBZT poly(p-phenylene benzobisthiazole) BBL and BBB benzimidazophenanthroline-type heteroaromatic ladder polymer. 

Figure 11.8 The steady-state viscosity for solutions of poly(l,4-phenylene-2,6-benzobisthiazole) (PBZT) with viscosity-averaged molecular weight 37,400 (molecular length 170 nm), in methane sulfonic acid at concentrations of 1.5 ( ), 2.52(H), 3.0(A), 3.43(0), 6.11(0). 8.2(Q)% (by...

Ordered polymer films made from poly benzthiazole (PBZT) and poly benzoxazole (PBO) can be used as substrates for multilayer printed circuit boards and advanced interconnects to fill the current need for high speed, high density packaging. Foster-Miller, Inc. has made thin substrates (0.002 in.) using biaxially oriented liquid crystal polymer films processed from nematic solutions. PBZT films were processed and laminated to make a substrate with dielectric constant of 2.8 at 1 MHz, and a controllable CTE of 3 to 7 ppm/°C. The films were evaluated for use in multilayer boards (MLBs) which require thin interconnect substrates with uniform controllable coefficient of thermal expansion (CTE), excellent dielectric properties, low moisture absorption, high temperature capability, and simple reliable processing methods. We found that ordered polymer films surpass the limitations of fiber reinforced resins and meet the requirements of future chip-to-chip interconnection. 

Recently, there is an apparent need in the U.S. Air Force for improved structural transparency materials with respect to higher use temperature than that of the current state-of- the-art materials based on polycarbonate and poly acrylates, for canopy and window applications. Although PBX polymers are known for their outstanding tensile and modulus properties as well as great tolerance to extremely harsh environments, they are intensely colored, for example, PBZT is pale yellow and PBO is deep-gold. This is the consequence of the highly delocalized 7t-electron density along their backbones.- As such, they cannot be used in areas where colorlessness and transparency are the prime requirements. 

The efficacy of this supramolecular engineering strategy was first demonstrated for heterocyclic rod-coil copolymers, with poly(p-phenylenebenzobisthiazole) (PBZT) and derivatives used as the rod-like segments(7Q). The wavelength of absorption and emission of rod-coil copolymers... 

The names of the rod-coil copolymers (Chart 1) used in this study are poly(l, 4-phenylenebenzobisthiazole-co-decamethylenebenzobisthiazole-co-(l, 4-phenylene-divinylene)benzobisthiazole) (PBZT-co-PBTClO-co-PBTPV, 1) poly(2,6-naphthylenebenzobisthiazole-co-decamethylenebenzobisthiazole-co-(1,4-phenylene-divinylene)benzobisthiazole) (PNBT-co-PBTC 10-co-PBTPV, 2) poly (1,4-phenylenebenzobisthiazole-co-decamethylenebenzobisthiazole)... 

The aromatic heterocyclic rodlike polymers poly(p-phenylenebenzobisoxazole) (PBO) and poly(p-phenylene-benzobisthiazole) (PBZT or PBT) [14—20] possess rigid rodlike structures which provide superior tensile properties and excellent thermal stability. Thermal analysis of PBO and PBT reveals minimal weight loss in air at 316 °C. Thermal decomposition of both polymers begins at 600 °C and reaches a maximum between 660 and 700 °C. The total weight loss for both PBO and PBT is about 28% at 1,000 °C [16]. 

Jiang H, Desai P, Kumar S, Abhiraman AS, Carbon-fibers from poly(para-phenylene benzobisthiazole) (PBZT) fibers—conversion and morphological aspects, Carbon, 29(4-5), 635-644, 1991. 

In pursuit of the general goal of producing polymers with better properties, but with easier processability than the ladder poljrmers, scientists in the Air Force Materials Laboratory successfully ssmthesized extended chain polymers, including poly((benzo l,2-d 4,5 -d bisthiazole-2,6-diyl)-l,4-phenylene) (PBZT) (3), poly((benzo l,2-d 4,5 -d bisoxazole-2,6-diyl)-l,4-phenylene) (PBZO) (4),... 

Syntheses of tetramethylbiphenyl PBZT-co-PBZT systems (139), dihydroxy PBZT and dihydroxy PBZT/PBZT copolymers (140), and monomethyl-pendant-poly (p-phenylene benzobisimidazole) (141) to form intermolecular hydrogen bonding. 

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