TY - JOUR
T1 - One-dimensional assembly of silica nanospheres
T2 - Effects of nonionic block copolymers
AU - Zhou, Shujun
AU - Sakamoto, Takeshi
AU - Wang, Junzheng
AU - Sugawara-Narutaki, Ayae
AU - Shimojima, Atsushi
AU - Okubo, Tatsuya
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2012/9/18
Y1 - 2012/9/18
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84866373217&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84866373217&partnerID=8YFLogxK
U2 - 10.1021/la302443f
DO - 10.1021/la302443f
M3 - Article
C2 - 22934598
AN - SCOPUS:84866373217
VL - 28
SP - 13181
EP - 13188
JO - Langmuir
JF - Langmuir
SN - 0743-7463
IS - 37
ER -