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Title: Molecular design, thin film polymerization and characterization of fluorinated liquid crystalline polymers
Keywords: thermotropic liquid crystalline polymers, fluorine, polyesters, poly(ester-amide)s, persistence ratio , in-situ thin film polymerization
Issue Date: 8-Aug-2006
Citation: TEOH MAY MAY (2006-08-08). Molecular design, thin film polymerization and characterization of fluorinated liquid crystalline polymers. ScholarBank@NUS Repository.
Abstract: The aim of this study was to synthesize fluorinated polyesters and poly(ester-amide)s and attempt to discover novel thin film liquid crystalline polymers (LCPs) by thin film polymerization. Detailed examination of ANA/AAA/perfluoroalkyl flexible spacers revealed that systems containing short perfluoroalky spacers (n = 2, 3) tended to remain in liquid crystal (LC) phase, while a long perfluoroalky spacer (n = 8) tended to crystallize. Both simulation and experimental results confirmed that ABA/AAA/TFTA (para) has the greatest tendency to yield LC formation, followed by ABA/AAA/TFIA (meta) and ABA/AAA/TFPA (ortho). The average Avrami exponent, n, was ~1.2, suggesting a mesophase transition in ABA/MH/TFTA film, while DSC results confirmed the phase transition in ABA/HQ/TFTA as crystali? nematici? isotropic. Optical microscope study showed that the surface microcracks formed during rapid quenching. The ABA/MH/TFTA film exhibits disclination strengths with S = +1 and - A?. However, disclination strengths with S = A?1 were observed in ABA/MH/TFIA system. Overall, all the above systems satisfied the minimum requirement, persistence ratio larger than 6.42, for LC formation by molecular science simulation.
Appears in Collections:Ph.D Theses (Open)

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