Crystalline Polymorphism of Alkyl Chains in Supramolecular Complexes of Polyethyleneimine with Octadecanoic Acid

Abstract

The supramolecular complexes of branched polyethyleneimine and octadecanoic acid (PEI(OA)x) were prepared via interfacial reaction and homogeneous solution complexation. The binding mode and the crystalline polymorphism of alkyl chains in PEI(OA)x were investigated by FTIR spectroscopy and WAXS. There are three kinds of OA exist in the complexes, the first one is bound by primary amines through proton transferring, the second one associated with PEI through hydrogen‐bonding, and the third one free OA. The crystal structure of alkyl chains in PEI(OA)x is different from that of complexes of linear poly(4‐vinylpyridine) and pentadecylphenol reported by G. ten Brinke group.[1] Hexagonal and orthorhombic and triclinic packing of alkyl chains may occur in PEI(OA)x with 0.32 ⪇ x ⪇ 4.16 and the hexagonal packing still occurs at high content of OA. The ordered packing of alkyl chains is determined by the binding mode of OA in PEI(OA)x as well as the specimen‐preparing process.

Structural Changes in a Polyelectrolyte Multilayer Assembly Investigated by Reflection Absorption Infrared Spectroscopy and Sum Frequency Generation Spectroscopy

“…These band positions in Figure 8a are in very good agreement with those seen by Cai et al, who used infrared spectroscopy to look at supramolecular complexes of PEI and octadecanoic acid (OA). 33 They attributed the shift in N-H scissoring modes to the protonation of the amine groups of PEI and assigned the band at 1406 cm -1 to the symmetric carboxylate stretch of the deprotonated acid. They also assigned the band at ∼1560 cm -1 to an overlap of the asymmetric carboxylate stretch and an N-H scissoring mode of a protonated amine.…”

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

“…In our previous investigations, [41][42][43][44] the lamellar architecture and crystalline transformations were reported for PEI(OA) x complexes (x represents the molar ratio of EI units to OA molecules), which were prepared through interfacial reactions. In the present work, a homogeneous reaction method was adopted for the synthesis of the PEI/ OA complexes in hot ethanol.…”

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

“…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.…”