One-dimensional assembly of silica nanospheres: Effects of nonionic block copolymers

Shujun Zhou, Takeshi Sakamoto, Junzheng Wang, Ayae Sugawara-Narutaki, Atsushi Shimojima, Tatsuya Okubo

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The effects of polymers on the one-dimensional assembly of silica nanospheres (SNSs) in the liquid phase are systematically investigated using nonionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (abbreviated as PEO-PPO-PEO) triblock copolymers with varying hydrophilic-lipophilic balance (HLB) values. Scanning electron microscopy is employed for morphological observations of the polymer-mediated assemblies of SNSs on the basis of which the optimal pH for 1D assembly (pH1D) is determined. To clarify the polymers' effects on the 1D assembly of SNSs, the relationships between pH1D and polymers' HLB values, the numbers of hydrophilic EO and hydrophobic PO units, and the relative ratio of N PO/NEO are examined. Zeta potential measurements are conducted to investigate the electrostatic repulsion among the SNSs in the presence of block copolymers. It is found that the relative hydrophilicity of the block copolymers greatly affects the balance of interactions in the 1D assembly of SNSs. Block copolymers with large HLB values promote the 1D assembly of SNSs under near-neutral pH conditions, whereas the block copolymers with small HLB values promote 1D assembly under basic pH conditions. Therefore, the 1D assembly of SNSs is achieved over an extensive pH range (7.5-9.5) through the employment of block copolymers of different hydrophilic and hydrophobic block lengths.

Original languageEnglish
Pages (from-to)13181-13188
Number of pages8
JournalLangmuir
Volume28
Issue number37
DOIs
Publication statusPublished - 2012 Sep 18
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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  • Cite this

    Zhou, S., Sakamoto, T., Wang, J., Sugawara-Narutaki, A., Shimojima, A., & Okubo, T. (2012). One-dimensional assembly of silica nanospheres: Effects of nonionic block copolymers. Langmuir, 28(37), 13181-13188. https://doi.org/10.1021/la302443f