Construction of lamellar morphology by side‐chain crystalline comb‐like polymers for gas barrier

Abstract A comb‐like polymer containing crystallized alkyl side chains and the intermolecular hydrogen bonds between the linking groups was fabricated by grafting long‐chain fatty amine onto poly(styrene‐co‐acrylic acid) n (P(S‐AA) n , wherein “n” denoted AA feed ratio). The chemical structures and crystallization behaviors of the comb‐like polymer P(S‐AA) n ‐g(p) (wherein “p” denoted the number of side‐chain carbon atoms) were analyzed by Fourier transform infrared, gel permeation chromatography, X‐ray photoelectron spectroscopy, and X‐ray diffractometer, differential scanning calorimetry, atomic force microscopy, respectively. It was found that the lamellar morphology could be generated by controlling the grafting density and side chain length of P(S‐AA) n ‐g(p). Moreover, it was identified that the hydrogen bonds between amide groups could enhance the crystallinity and then adjust the interlamellar spacing of lamellar phase. As a result, P(S‐AA) 70 ‐g(18) with the highest degree of crystallinity and closely packed lamellar morphology showed a good gas‐barrier performance, and the nitrogen permeability reached 1.78 × 10 −14 cm 3 ·cm/cm 2 ·s·Pa. Furthermore, the permeation switch of the obtained comb‐like polymer could reach 500 times traversing the melting point.