ORIGINAL CONTRIBUTION
Reversible thermoresponsive behavior of poly(2-chloroethyl
vinyl ether-alt-maleic anhydride) in mixed solvent
of tetrahydrofuran/hexane
Zhenjie Liu
&
Yongliang Guo
&
Katsuhiro Inomata
Received: 28 December 2010 / Revised: 24 January 2011 /Accepted: 1 February 2011 / Published online: 3 March 2011
#
Springer-Verlag 2011
Abstract Poly(2-chloroethyl vinyl ether-alt-maleic anhy-
dride) can exhibit lower critical solution temperature-type
phase behavior reversibly by tuning the solvent composi-
tion in mixed solvent of tetrahydrofuran (THF) and
hexane. The effect of solvent composition and polymer
concentration on cloud point of polymer solution was
investigated. The cloud point temperature for high
molecular weight polymer was lower than that for lower
molecular weight polymer. High resolution
1
HNMR
spectra in mixed solvent of THF-d
8
and hexane were also
measured for comprehending thermoresponsive behavior
of polymer solution in molecular level; however, any
discontinuous change in the NMR signals around the
cloud point could not be recognized.
Keywords Stimuli-sensitive polymers
.
Thermoresponsive
polymers
.
Solution properties
.
Phase behavior
.
Lower
critical solution temperature
.
Organic media
Introduction
Thermoresponsive polymers can undergo relatively large
and abrupt physical or chemical property changes in
response to small external changes of temperature in the
environment, and those polymers generally have a lower
critical solution temperature (LCST) or upper critical
solution temperature (UCST). Most interest is related to
LCST-type polymers, and based on this kind of polymers,
many applications have also been developed [1–3].
As for LCST-type phase behavior of polymers in water,
some theories have been developed in order to predict the
thermoresponsive behavior and discover new polymers
which can exhibit LCST-type phase behavior [4–6], and
water-soluble thermoresponsive polymers have been used
in many fields [1,6–9] such as controlled drug delivery [7],
thermoresponsive stabilizers [8], and bioconjugates [1].
However, in the past, LCST-type phase behavior of
polymers in organic media did not attract so much
attention, and one of the reasons may be that LCST of
conventional polymer systems in organic media occurs at
some tough conditions such as near or above boiling point
of solvent, so it is not convenient to study this kind of
phenomena [10–17]. Nowadays, LCST-type phase behavior
in organic media at mild conditions has started to attract
some interest, but only a few novel examples have been
reported [18–20], for example, polymers capped by
fluoroalkyl groups [18], heat-set gel-like networks of
lipophilic Co(II) triazole complexes [19], and polymers
with ionic liquid pendants [20].
Here, we report an organic polymer solution system
which can exhibit LCST-type phase behavior at mild
conditions. In our former article, we simply reported the
phenomenon that alternating copolymer of 2-chloroethyl
vinyl ether and maleic anhydride (P(CVE-MA)) can present
LCST-type phase behavior in proper organic media [21]. It
is commonly reported that some polymers can exhibit
LCST-type phase behavior in mixed solvent of water and
organic media [22–31]. However, it is novel that organic
Z. Liu
:
Y. Guo
:
K. Inomata (*)
Department of Materials Science and Engineering,
Nagoya Institute of Technology,
Gokiso-cho, Showa-ku,
Nagoya 466-8555, Japan
e-mail: inomata.katsuhiro@nitech.ac.jp
Y. Guo
Department of Materials Science and Engineering,
Beijing University of Chemical Technology,
Beijing 100029, China
Colloid Polym Sci (2011) 289:791–798
DOI 10.1007/s00396-011-2395-y