ORIGINAL CONTRIBUTION
Preparation of poly(ε-caprolactone)@attapulgite
nanocomposites via a combination of controlled ring-opening
polymerization and click chemistry
Jiucun Chen
&
Haodong Wang
&
Wenqian Luo
&
Jiming Xiang
&
Lihui Zhang
&
Baoben Sun
Received: 28 August 2009 /Revised: 25 October 2009 /Accepted: 28 October 2009 /Published online: 3 December 2009
#
Springer-Verlag 2009
Abstract In this work, by a combination of controlled
ring-opening polymerization (CROP) and click chemistry,
we report a facile and useful method to synthesize linear
poly(ε-caprolactone)@attapulgite nanocomposites with
well-defined structures. For this, first, the chlorine-
terminated attapulgite was prepared by the self-assembly
of 3-chloropropyltrimethoxysilane from the surfaces of
attapulgite. And then, the terminal chlorines of modified
attapulgite were substituted with azido groups. As the
second step, linear propargyl-terminated poly(ε-caprolac-
tone) (PCLs) with different molecular weights were
synthesized by the CROP of ε-CL monomer in toluene
with stannous octoate as a catalyst and propargyl alcohol as
an initiator. The structural characteristics of the obtained
linear PCLs have been determined by
1
H NMR and gel
permeation chromatography analysis. Finally, the azido-
terminated attapulgite was reacted with propargyl-
terminated PCLs via the click reaction.
Keywords Attapulgite
.
CROP
.
Click chemistry
.
Surface modification
Introduction
Polymer/clay nanocomposites represent a new class of
materials, which have attracted much attention because
of their excellent physical properties such as high-
dimensional stability, gas barrier performance, flame
retardancy, and mechanical strength when compared to
the pure polymer or conventional composites (micro-
and macrocomposites) [1–6]. Attapulgite (AT, or paly-
gorskite as it often called) is a crystalline-hydrated
magnesium aluminum silicate with reactive –OH groups
on its surface; it is a natural nanostructural material, and
itsidealstructurewasstudiedbyBradleyearlyin1940
andshowninFig.1 [7]. The distinguishing feature of its
structure is that the Si–O tetrahedron forms long strips,
each an amphibole unit wide on alternate sides of the
oxygen sheet in a manner which confers a regular
corrugated Si–O structure [8]. This structure results in
zeolite-like channels, which are approximately 3.7×6.0
and 5.6×11.0Å wide, respectively [9]. The high surface
area, the charge on the lattice, and the inverted structure,
which leaves parallel channels through the lattice, give
AT a high absorption capacity. This, along with the
elongate habit of the minerals, makes it particularly useful
in many industrial applications. At present, AT has been
used as adsorbent [10], in drilling muds [11], in
pharmaceutical preformulation study [12], and as animal
feed supplement [13], but there are few reports about its
use in the nanocomposites grafted with polymers.
As a US Food and Drug Administration-approved
biomedical polymer, biodegradable poly(ε-caprolactone)
(PCL) and PCL-based biomaterials have been increasingly
investigated for pharmacological and biomedical applica-
tions [14, 15]. Moreover, PCL is of great interest in
biomedical research because of its low cost, slow degrada-
tion, high permeability to many drugs, and nontoxicity [16].
The science of “click chemistry” introduced by Sharp-
less, can be used for the synthesis of drug molecules
through practical and reliable reactions [17]. An example of
the click reaction is the copper(I)-catalyzed variant of the
Huisgen reaction, which involves 1,3-dipolar cycloaddition
J. Chen
:
H. Wang (*)
:
W. Luo
:
J. Xiang
:
L. Zhang
:
B. Sun
Department of Chemistry, Ankang University,
Ankang,
Shannxi 725000, People’s Republic of China
e-mail: wanghdakxy@163.com
Colloid Polym Sci (2010) 288:173–179
DOI 10.1007/s00396-009-2150-9