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Synthesis and characterization of main chain thermotropic liquid crystalline polyesters based on methyl 4-[4 '-(omega-hydroxyalkoxy)blphenyl-4-yl]-4-oxobutyrate: Effects of keto group and connectivity on mesophasic characteristics of biphenyl based AB-type polyesters

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Title Synthesis and characterization of main chain thermotropic liquid crystalline polyesters based on methyl 4-[4 '-(omega-hydroxyalkoxy)blphenyl-4-yl]-4-oxobutyrate: Effects of keto group and connectivity on mesophasic characteristics of biphenyl based AB-type polyesters
 
Creator RANGANATHAN, T
RAMESH, C
 
Subject mesogenic 4,4'-biphenyldicarboxylate unit
para,para'-bibenzoic acid
self-polycondensation
flexible spacers
smectic phase
polymers
4,4'-dihydroxybiphenyl
behavior
homopolyesters
polyurethanes
liquid crystalline polyesters
biphenyl mesogen
ab approach
effect of connectivity
 
Description A series of biphenyl based main chain thermotropic liquid crystalline polyesters, poly(hydroxyalkoxybiphenyl oxobutyrate) [PRBOB-2,n (n = 2-8)], containing various methylene spacers was synthesized by using the novel AB-type self-polycondensation route from the monomers, methyl 4-[4'-(omega-hydroxyalkoxy)biphenyl-4-yl]-4-oxobutyrate (HBOB-2,n). The mesophase characteristics of these polyesters was studied using DSC, polarized light optical microscopy and XRD techniques. The transition temperatures were found to decrease upon increasing the spacer length with an even polymer exhibiting higher transition temperature than the odd counterpart. The mesophase type also indicated an odd-even oscillation with the even members showing normal smectic phase and odd members exhibiting tilted smectic phase. The comparison of mesophasic characteristics of these polyesters with that of structurally similar AB-type polyesters indicated that the total number of atoms connecting the mesogen in a polymeric repeat unit governs the nature of the mesophase while the rigidity of the system dictates the magnitude of transition temperatures. (c) 2006
 
Publisher ELSEVIER SCIENCE BV
 
Date 2011-07-26T22:28:56Z
2011-12-26T12:56:03Z
2011-12-27T05:44:11Z
2011-07-26T22:28:56Z
2011-12-26T12:56:03Z
2011-12-27T05:44:11Z
2006
 
Type Article
 
Identifier REACTIVE & FUNCTIONAL POLYMERS, 66(10), 1003-1013
1381-5148
http://dx.doi.org/10.1016/j.reactfunctpolym.2006.01.019
http://dspace.library.iitb.ac.in/xmlui/handle/10054/7035
http://hdl.handle.net/10054/7035
 
Language en