A Tetramethylbiphenyl Poly(benzobisthiazole):  Synthesis, Chracterization, Fiber Spinning, and Properties

Abstract

Poly(benzobisthiazole)s containing an o-tetramethyl substituted biphenyl moiety were synthesized based on 2,5-diamino-1,4-benzenedithiol dihydrochloride and 2,2′,6,6′-tetramethylbiphenyl-4,4′-dicarbonyl chloride. Homopolymerization of the two monomers and copolycondensation of the two monomers with terephthaloyl chloride were carried out in poly(phosphoric acid) (PPA). The interfacial polymerization technique was used to enhance the formation of a homogeneous liquid crystalline polymer solution suitable for fiber spinning. Copolymers of tetramethylbiphenyl PBZT/PBZT (25/75) were successfully spun into fibers from liquid crystalline solutions in PPA. Fibers were thermally cross-linked between 500 and 550 °C. The thermal cross-linking reaction was studied by thermogravimeteric analysis and by 13 C solid-state NMR spectroscopy. Fiber morphology and properties are also reported and discussed.

Modeling the effect of crosslinking in methyl-pendant poly(p-phenylene benzobisthiazole)

“…However, the loss of methane suggests direct phenyl-phenyl crosslinking. 12 Hu et al 14 have synthesized a tetramethyl-biphenyl PBZTco-PBZT system that shows improved compressive strength with only 2.5% degree of crosslinking.…”

Rigid‐Rod Polymers

“…By incorporating a thermally reactive cross-linking moiety fluorene into PBZT (267,268), iii. Cross-linking benzobisthiazole rigid-rod copolymers via labile methyl or dimethylephenoxy pendent groups (261,(269)(270)(271)(272)(273)(274)(275), or forming copolymers of tetramethylbiphenyl PBZT/PBZT (276,277), iv. Cross-linking PBO fibers with polyphenylene sulfide pendent groups (278), and v. Cross-linking PBZT by introducing benzocyclobutene (BCB) crosslinking moieties in PBZT backbone (264,270,(279)(280)(281)(282).…”

Liquid crystalline organic fibres and their mechanical behaviour

“…From a general point of view, the compressive properties depend on the type and degree of intermolecular interactions present in the fibres (Deteresa et al, 1988;Northolt and Sikkema, 1991;Hu et al, 2000;Northolt and Batussen, 2002;Chae and Kumar, 2006). Figure 12.39 shows as the compressive strength increases as the energy of the hydrogen bonds increases for heterocyclic rigid-rod polymer fibres.…”

“…Compressive strength as a function of hydrogen bonding for heterocyclic rigid-rod polymer fibres (Chae and Kumar, 2006;Hu et al, 2000).…”