Open AccessCrystallization as a Means for the Switching of Nanoscale Containers
Author(s) -
Qiong Tong,
Marina Krumova,
Inigo GöttkerSchnetmann,
Stefan Mecking
Publication year - 2008
Publication title -
langmuir
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.042
H-Index - 333
eISSN - 1520-5827
pISSN - 0743-7463
DOI - 10.1021/la702500n
Subject(s) - crystallinity , branching (polymer chemistry) , crystallization , amorphous solid , chemical engineering , polymerization , materials science , nanoscopic scale , polymer , molecule , aqueous solution , particle (ecology) , microstructure , polymer chemistry , nanotechnology , chemistry , crystallography , organic chemistry , composite material , oceanography , geology , engineering
Melting and crystallization are reported as a means for reversible switching of nanoscale containers. Aqueous dispersions of 10 nm particles of polyethylene with variable branching and crystallinity were prepared by catalytic polymerization with water-soluble Ni(II) complexes. Fluorescence studies of lipophilic probe molecules show that in the low-crystallinity particles they experience a more apolar environment. In crystalline particles, the amorphous portions which can accommodate guest molecules are at the periphery of the particle, such that the probe experiences the water-particle interface to some extent. The polarity experienced by the probe molecules can be switched reversibly by melting and crystallization of the individual dispersed particles. The temperature at which this occurs can be adjusted via the microstructure, that is, degree of branching, of the polymer.
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