Abstract
A new homologous series of thermotropic liquid crystalline copoly(arylidene-ether)s based on 4-teriary butyl cyclohexanone moiety were synthesized by solution polycondensation of 4,4’-diformyl-α,ω-diphenoxyalkanes, Ia-d or 4,4’- diformyl-2,2’-dimethoxy-α,ω-diphenoxyalkanes IIa-d with the 4-teriary butyl-cyclohexanone III and cyclopentanone. A model compound IV was synthesized from the monomer III with benzaldehyde and characterized by elemental and spectral analyses. The inherent viscosities of the resulting polymers were in the range 0.22 - 0.92 dI/g. All the copoly(arylidene-ether)s were insoluble in common organic solvents but dissolved completely in concentrated H2SO4 and formic acid. The mesomorphic properties of these polymers were studied as a function of the diphenoxyalkane space length. Their thermotropic liquid crystalline properties were examined by DSC and optical polarizing microscopy and demonstrated that the resulting polymers form nematic mesophases over wide temperature ranges. The thermogravimetric analyses of those polymers were evaluated by TGA and DSC measurements and correlated to their structural units. X-Ray analysis showed that copolymers having some degree of crystallinity in the region 2q = 5° -60°. In addition, the morphological properties of selected examples were tested by Scanning electron microscopy.
Highlights
Thermotropic liquid crystalline behavior of polymeric materials is of considerable current interest, because of their potential as high-strength fibers, plastics, moldings etc. [1,2,3], and because of their unique position in the theoretical scheme of structural order in liquid phases [4]
A new homologous series of thermotropic liquid crystalline copoly(arylidene-ether)s based on 4-teriary butyl cyclohexanone moiety were synthesized by solution polycondensation of 4,4’-diformyl-α,ω-diphenoxyalkanes, Ia-d or 4,4’diformyl-2,2’-dimethoxy-α,ω-diphenoxyalkanes IIa-d with the 4-teriary butyl-cyclohexanone III and cyclopentanone
All the copoly(arylidene-ether)s were insoluble in common organic solvents but dissolved completely in concentrated H2SO4 and formic acid
Summary
Thermotropic liquid crystalline behavior of polymeric materials is of considerable current interest, because of their potential as high-strength fibers, plastics, moldings etc. [1,2,3], and because of their unique position in the theoretical scheme of structural order in liquid phases [4]. [1,2,3], and because of their unique position in the theoretical scheme of structural order in liquid phases [4]. These thermotropic liquid crystalline (mesomorphic) polymers have two basic types [5]: one type has flexible aliphatic spacer groups, used to insulate the delicate intermolecular interactions in the liquid crystalline portions from small, but disruptive motions of the main chain. Attention was addressed to 4-teriary-butyl-cyclohexanone moiety to prepare new thermotropic liquid crystal homo- and copoly(arylidene-ther)s. ALY racterization of these polymers such as thermostability, solubility, morphology, and crystallinity were discussed
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