Synthesis and Characterisation of Side‐Chain Liquid Crystalline Poly[1‐({[(4‐cyano‐4′‐biphenyl)oxy]alkyl}oxy)‐2,3‐epoxypropane]

Abstract

Summary: A new series of side‐chain liquid‐crystal polymers, the poly[1‐({[(4‐cyano‐4′‐biphenyl)oxy]alkyl}oxy)‐2,3‐epoxypropane], has been synthesized in which the spacer length is varied from 2 to 8 methylene units. The synthesis used for the chemical modification of polyepichlorohydrin (PECH) involved the phase transfer catalyzed etherification of the chloromethyl groups with sodium 4‐cyano‐4′‐biphenoxide and lithium n‐(4‐cyano‐4′‐oxybiphenyl)‐alkanoates. All the resulting polymers (except polymers 7 and 8), including that without spacer, characterized by 1H NMR, and IR, exhibit thermotropic liquid crystalline mesomophism. The thermal behavior of the polymers has been characterized using differential scanning calorimetry (DSC) and polarized light microscopy (POM) equipped with hot‐stage. A more pronounced odd‐even effect in the clearing temperatures is observed on increasing the spacer length in which the odd members display slightly higher values, which were also dependent on the substitution degree of PECH. The flexible PECH chain assists nematic LC formation compared with other more rigid backbone polymers where a smectic phase is often encountered with the same mesogen. A comparison of the thermal properties of the cyanobiphenyl based series reported here. Polyacrylate (PA) and poly(methacrylate)‐based (PMA) SCLCPs containing 4‐cyanobiphenyl as the mesogenic unit are consistent with the general rule that increasing backbone flexibility for a given mesogenic unit and spacer length enhance the clearing temperature. This was not found from the PECH‐based series, which show the lower clearing temperature than the PMA and PA series, even though they have more flexible backbone than PA and PMA series. So the clearing temperature is not solely determined by the flexibility of the backbone.Schlieren textures of PECHOC2‐B taken at 110 °C (cooling from isotropic phase after annealing 1 h).magnified imageSchlieren textures of PECHOC2‐B taken at 110 °C (cooling from isotropic phase after annealing 1 h).

Spatial distribution control of polymer nanoparticles by liquid crystal disclinations

“…We synthesized perylene-labeled [28][29][30][31][32] HBPs with mesogenic shells [24][25][26] (1) as shown in Scheme 1 that could be dispersed in a nematic liquid crystal and studied the behavior of HBPs captured by disclinations using confocal fluorescence polarizing microscopy. 33,34 A perylene derivative with a methacryl group (2) was introduced to the HBP using photo-copolymerization.…”

“…17 A liquid crystalline monomer, 5-(4-cyanobiphenyl-4 0 -yloxy)pentyl methacrylate (3) was prepared from 4-cyano-4 0 -hydroxybiphenyl using a procedure described by Craig et al 24 The precursor, N-(1-hexylheptyl)perylene-3,4:9,10-tetracarboxy-3,4-anhydride-9, 10-imide, 25 was prepared according to a procedure similar to that found in the literature. 26 The synthesis of methacryl derivatives is illustrated in Supplementary Information Scheme S1.…”

Synthesis and Thermal Properties of Poly(2-Chloroethyl Glycidyl Ether)-Based Side-Chain Liquid-Crystalline Polymers

“…Polyepichlorohydrin is usually used as the main chain of polyether-based SCLCPs and it can react with many compounds containing a mesogenic unit to form liquid-crystalline compounds [11][12][13][14][15]. However, the disadvantage of polyepichlorohydrin is the absence of on extra spacer.…”

Chemical Modification of Poly(epichlorohydrin) Using Montmorillonite Clay

“…This facilitates the nucleophilic substitution for side chain modification, and the absence of phenyl groups would have stiffened the polymer chains in the case of styrene polymers [4][5][6] in addition to the presence of a flexible backbone. [7][8][9][10][11] Much attention has been paid to the modification of PECH with a large number of nucleophiles such as azides, 12 carbazole, 13 carboxylates, 14,15 sulphur compounds 12,[16][17][18] and phenolates [19][20][21] either under conventional conditions or under phase transfer catalysis (PTC) conditions. [22][23][24] On this basis, the present work deals with the preparation of PECH through cationic ring opening polymerization followed by nucleophilic displacement of chlorine functionality with heterocyclic amines using Mghnite-H ＋ catalyst, a new non-toxic cationic initiator, heterocyclic monomers 25,26 and vinyl monomers.…”