Liquid Crystalline Fluorocarbon Side-Chain Polyesters

Abstract

Perfluoroalkyl side-chain polyesters of the type -[0(CH2)2N{S02(CF2)gF}(CH2)202C(CH2)m-CO]"-, with m = 2-4,8,12, and 20, have been synthesized in high yield directly from the diacid and the diol, using a coupling agent. Molecular weights up to 40 000 were obtained. The polyesters with m > 3 showed enantiotropic mesophases, although they have no flexible spacer between the main chain and the side-group mesogen. The rigid perfluoroalkylsulfonamide group and the segregating tendency of fluorocarbons and hydrocarbons give these polyesters their liquid crystalline behavior. The mesophases were investigated by polarizing optical microscopy, DSC, and rheological DMA. They have a grainy optical texture in the POM, multiple transitions in the DSC and a low-viscosity mesophase regime in mechanical analysis.

Nanoindentation of Films of Perfluorotridecyl, Perfluorodecyl, and Perfluoroheptyl End‐Functionalized Polystyrene at the Micron Scale

“…This polymer has been shown to exist in four different helical crystalline states I–IV, depending on temperature and pressure and appears to be susceptible to rapid helix reversals at elevated temperatures . In agreement with the above, numerous polymers containing RF pendent‐ or end groups have been shown to exhibit mesogenic properties . In addition perfluorocarbons and RF groups have been shown to give exceptionally low‐surface free energies .…”

Mesomorphic phase transition behavior of novel triphenylene compounds possessing fluoroalkylated side chains

“…In general, terminal fluoro-, trifluoromethyl-, and trifluoromethoxy-substituted mesogenic molecules have been shown to be useful by themselves, or as additives for formulated practical mixtures with other more conventional cyano-terminated mesogens, because they are chemically stable and possess moderate positive dielectric anisotropy with lower viscosity [1]. It was reported that the fluorophilic and fluorophobic interactions around fluoroalkyl chains enhance the mesophase thermal stability and facilitates the formations of the smectic phase [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Furthermore, it was reported that the combination of the suitable length of aliphatic chain and the ratio of the perfluorinated alkane segment to the perhydrogenated one in the chain relates to the microsegregation at the molecular level [21][22][23][24][25][26][27][28].…”

Effects of chemical variations on the mesophase behavior of new fluorinated poly(vinylcyclopropane)s

“…The incorporation of fluorine in a polymer causes the polymer to have a low surface energy [10,11] potentially leading to low wettability, low friction coefficient and low adhesion [12][13][14][15][16]. Commercially available fluorinated ester side chain acrylic and methacrylic polymers are typical low surface energy coating materials [17].…”