Nanofibers

Polymer 50 (2009) 3652–3660

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Polymer
journal homepage: www.elsevier.com/locate/polymer

Colloidal poly(styrene-co-butyl acrylate)/multi-walled carbon nanotubes
nanocomposite by heterocoagulation in aqueous media
Sanghyun Hong a, Jinho Hong a, Dongsoo Jung b, Sang Eun Shim a, *
a
b

Department of Chemical Engineering, Inha University, 253Yonghyundong, Namgu, Incheon 402-751, South Korea
Department of Mechanical Engineering, Inha University, 253 Yonghyundong, Namgu, Incheon 402-751, South Korea

article info

abstract

Article history:
Received 20 December 2008
Received in revised form
25 April 2009
Accepted 13 May 2009
Available online 9 June 2009

Colloidal nanocomposite particles were prepared by heterocoagulation ofcarbon nanotubes (CNTs)
dispersion stabilized by cationic hexadecyltrimethylammonium bromide (CTAB) and negatively charged
poly(styrene-co-butyl acrylate), P(St-co-BA), latex prepared by conventional emulsion polymerization in
aqueous medium with the aid of a flocculant, polyaluminium chloride (PAC), at elevated temperature
above the Tg of P(St-co-BA). The hybrid nanocomposite particles wereprepared by a simple procedure
consisting of mixing two dispersions, particle growth, and stabilization steps. The effects of the surface
properties of CNTs, molecular weight of latex polymer, types of flocculants and its optimum concentration were investigated. At a well-controlled condition, the spherical or potato-like particles in the size
range of 10–100 mm were achieved. After film formationof the nanocomposite particles, it was able to
confirm that CNTs were uniformly distributed without agglomeration in the matrix, resulting in the
percolation at a low concentration of CNTs.
Ó 2009 Elsevier Ltd. All rights reserved.

Keywords:
Nanocomposites
Colloids
Heterocoagulation

1. Introduction
Due to the superior physical and chemical properties, carbon
nanotubes (CNTs) havegained significant popularity in materials
science since the discovery [1–3]. Young’s modulus is over 1 TPa
and the tensile strength is about 200 GPa. Additionally, they show
metallic or semimetallic electric property according to the band
structure [4–6]. These outstanding properties can be best exploited
by incorporating CNTs into some forms of matrix. Therefore the
preparation ofCNT-containing composite materials is now a rapidly
growing research area. In polymer society, CNTs are considered as
an ideal filler to open new area by which various novel properties of
composites can be achieved [7,8].
In order to use CNTs as a filler in polymers, it is crucial to make
CNTs uniformly dispersed in host matrix. Either chemical or
physical treatment of CNTs has been practiced to minimizeselfagglomeration of CNTs, thereby to improve uniformity of dispersion. In chemical treatments, CNTs are covalently functionalized to
have hydroxyl or carboxyl group. Although the functional groups
are permanently preserved, the significant damages to the molecular framework of CNTs including sidewall opening, breaking, and
transformation to amorphous carbon are resulted [9]. In turn, the

*Corresponding author. Tel.: þ82 32 860 7475; fax: þ82 32 872 0959.
E-mail address: seshim@inha.ac.kr (S.E. Shim).
0032-3861/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.polymer.2009.05.060

deterioration of the properties of CNTs is experienced. Furthermore, environmental pollution is an inevitable problem. On the
other hand, physical treatments of CNTs canovercome such problems in which CNTs are encapsulated by surfactants or dispersants.
Although the choice of solvent is limited, the physical method has
significant merits since the process is quite simple and the structure and properties of CNTs are unchanged [10].
CNT/polymer nanocomposites have been prepared by several
conventional routes; melt compounding [11], in-situ polymerization [12], and...