Molecular-weight dependence of the formation of highly ordered lamellar structures of poly(: N -dodecyl acrylamide) by humid annealing

Kazuki Ebata, Yuki Hashimoto, Kohei Ebara, Mayu Tsukamoto, Shunsuke Yamamoto, Masaya Mitsuishi, Shusaku Nagano, Jun Matsui

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2 Citations (Scopus)

Abstract

The molecular-weight dependence of the formation of highly ordered lamellar structures of poly(N-dodecylacrylamide) (pDDA) during humid annealing was studied. For this purpose, pDDA polymers with a number-average molecular weight (M n ) ranging from 1200 to 52000 were synthesized by free radical polymerization. Thin films of these polymers were prepared by spin-coating and their structures were examined by X-ray diffraction (XRD) and FT-IR measurements. The XRD patterns of the spin-coated films showed a broad halo at q = 2 nm -1 , which was attributed to scattering from nanosegregated alkyl domains in the case of pDDA with M n ≥ 3500 and to semi-crystalline lamellar domains in the case of pDDA with M n = 1200. Subsequently, the films were annealed at 60 °C and 95% relative humidity (humid annealing), which resulted in the formation of lamellar structures for pDDA films with M n ≥ 3500, whereby the long-range ordering of the films increased with the M n of the pDDA polymers. In contrast, pDDA with M n = 1200 afforded a semi-crystalline film even after 96 h of humid annealing. The higher M n polymers showed more disordered alkyl side chains and main chains in the lamellar film. Thus, it was concluded that the segregation between the alkyl side chains and main chains, which contain water-adsorbed amide groups, should be the driving force for the observed structural changes. Our results suggest that unique self-assembled structures can be obtained by humid annealing even from amorphous homopolymers.

Original languageEnglish
Pages (from-to)835-842
Number of pages8
JournalPolymer Chemistry
Volume10
Issue number7
DOIs
Publication statusPublished - 2019 Feb 21

ASJC Scopus subject areas

  • Bioengineering
  • Biochemistry
  • Polymers and Plastics
  • Organic Chemistry

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