Mesogen‐Free Supramolecular Liquid Crystalline State Formed by a Polyelectrolyte/Amphiphile Complex

Abstract

Summary: The microstructure and phase transformation of a highly‐branched polyethyleneimine/octadecanoic acid (PEI(OA)1.0) complex were investigated using a combination of DSC, XRD, optical polarised microscopy and temperature dependent FT‐IR spectroscopy. A mesogen‐free thermotropic liquid crystalline state was observed in a certain temperature region. The strong ionic interaction between COO− (from OA) and NH (from PEI) and the hydrophobic interaction between the alkyl side chains contributes to the formation of a thermotropic liquid crystalline structure. magnified image

Phase Transition and Side-Chain Crystallization of Poly(methyl vinyl ether-alt-maleic anhydride)-g-Alkyl Alcohol Comb-like Polymers

“…Comb-like polymers are an interesting topological polymer, and the characteristic hierarchical structure is regulated by polymeric backbone and side alkyl chains. , Different from the linear polymers, comb-like polymers give remarkable characteristics such as the mesophase formation, − the critical length requirement, − and the varied chain packing mode. − Considering the chain stacking and its assembled structure, they have been widely studied as a template to understand the crystallization habit and the ordered morphology of molecular chains. − …”

Frustrated crystallisation and hierarchical self-assembly behaviour of comb-like polymers

“…Similarly, the layered packing structures of comb-like supramolecular copolymers prepared by noncovalent interactions, such as hydrogen bonding or charge transfer, have also been observed by Wang et al, [66][67][68][69][70]72,74 Tirrell et al, 172,173 Thu ¨nemann et al 17,65,174 and Ikkala et al 52,55,56,59,[175][176][177] Their results demonstrated that the layered structures alternating with double layers of alkyl side chains and polymer layers exhibited the dependence on the charge density of the polymer and the chemical nature of both the main chains and the side chains. Besides the interdigitated packing manner of alkyl side groups, Wang et al also reported another packing mode of the complexes of branched PEI-octadecanoic acid (PEI(OA)x), where x characterized the average numbers of OA per EI repeat unit and x = 0.60, 0.76, 0.96, 1.03, 1.13, or 1.67.…”

“…62 Takahashi et al prepared comb-like complexes composed of polyethyleneimine (PEI) and aliphatic carboxylic acids, such as stearic acid (SA) or oleic acid (OA), in which the corresponding comb complexes were obtained depending upon the ionic bond interaction between the carboxylic acid molecules and the imine groups of the PEI backbone. 63 Thereafter, some interesting comb-like complexes based on polyamine (PEI and polyallylamine (PAA)), [64][65][66][67][68][69][70][71] poly(propylene carbonate) (PPC) [72][73][74] and carboxylic acid, fluorinated acids 75 or dodecylbenzenesulfonic acid 76 were systematically fabricated. The factors affecting the formation of comb-like supramolecular complexes were also analysed in detail with the chain length varying from 4 to 16 and the molar ratio of carboxyl groups.…”

Improving thermal stability of biodegradable aliphatic polycarbonate by metal ion coordination

“…Many of these complexes have flexible backbones and show pronounced tendency of forming thermotropic liquid crystals with lamellar microphase-separated nanostructures [9,12,13]. It was reported previously that the fatty acid, as a kind of common surfactant, can form comb-like liquid crystalline complexes without mesogenic units when associating with flexible polymers like poly(ethyleneimine) (PEI) [17][18][19][20]. These complexes exhibit typical smectic texture even with temperature rising above the melting point of the fatty acid, and this phenomenon has been observed by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) [17,18,20,21].…”

“…It was reported previously that the fatty acid, as a kind of common surfactant, can form comb-like liquid crystalline complexes without mesogenic units when associating with flexible polymers like poly(ethyleneimine) (PEI) [17][18][19][20]. These complexes exhibit typical smectic texture even with temperature rising above the melting point of the fatty acid, and this phenomenon has been observed by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) [17,18,20,21]. The association mode of these complexes was further investigated by Fourier transform infrared spectroscopy (FT-IR), and it was found that the specific interactions between functional groups of PEI and fatty acid play a key role in stabilizing the mesomorphous structures at high temperatures [18,20,21].…”