Ionic liquid as Functional Dispersant for Nanomaterials in Polymer Matrix-Juniper Publishers
JUNIPER
PUBLISHERS- ACADEMIC JOURNAL OF POLYMER SCIENCE
Abstract
Ionic liquid has been used as a novel dispersant for 
fillers in polymer matrix. Enhanced interfacial interaction between 
reinforcing material and polymer matrix leads to smart materials. Use of
 ionic liquid as a modifier is environmentally friendly method to 
fabricate nanocomposites potential applications.
Keywords:  Ionic liquid; Polymer matrix; Interfacial interaction; Potential applications
Abbrevations: 
 RTILs: Room-Temperature Ionic Liquids; MWCNT: Multiwalled Carbon 
Nanotube; GO: Graphene Oxide; BNNS: Boron Nitride Nanosheets; BIIR: 
Bromo butyl Rubber; ILs: Ionic Liquids; GO-ILs: Modified Graphene Oxide;
 MEMS/NEMS: Micro/Nanoelectromechanical Systems; ZIL: Zwitterionic 
Imidazolium-Based Ionic Liquid
Ionic liquid as a Functional Dispersant for Nanomaterials in Polymer matrix
Potential applications as well as strength and 
durability of polymers can be enriched by the reinforcement using 
various nanosized fillers. However wide spread application of 
nanomaterials as reinforcing agents has limited due to their processing 
difficulty and the tendency to form agglomerates. Incorporation of 
active groups on fillers by emerging chemistry is a good method to 
overcome the problems associated with filler dispersion. At present, 
many advanced strategies have been developed to improve the 
dispersibility and stability of nanofillers in solvents and matrices 
which include (a) the covalent attachment of functional groups through 
chemical reactions (b) the non-covalent adsorption or wrapping of 
various functional molecules. Due to some structural alteration and the 
need of additional solvent during covalent fictionalisation, 
non-covalent functionalization is preferred.
Non-covalent functionalization of fillers by 
Room-Temperature Ionic Liquids (RTILs) has got considerable attention in
 these days. RTILs, usually liquid at or near room temperature are 
non-volatile, non-flammable and thermally stable. They provide an 
environmentally benign “green” alternative to organic solvents for 
chemical synthesis, extractions and bio catalysis [1].
Use of ionic liquid as novel dispersant for fillers 
has been developed as an environment friendly technology to 
functionalize them. Commonly reported dispersants are solid in state 
which needs additional solvent to disperse nanomaterial. In contrast
ionic liquids are fluid at room temperature and are made entirely of 
ions (asymmetric cation and a symmetric anion) [2].
Das et al. first reported the use of ionic liquid as a
 dispersing agent for Multiwalled Carbon Nanotube (MWCNT) [3]. Cation-Ï€ 
interaction between cationic part of ionic liquid and π conjugated MWCNT
 surface is the reason behind the dispersion of MWCNT. Since ionic 
liquid can act a dispersant, it will improve overall performance of the 
nanocomposites. Researches from the same group had tried different ionic
 liquids to functionalize MWCNT and studied its effect on various 
properties of fabricated nanocomposites. These studies showed a clear 
evidence for the enhanced dispersion of MWCNT in presence of ionic 
liquid, improved cure characteristics, mechanical performance, 
dielectric characteristics, electrical conductivity, ionic conductivity,
 thermal stability, thermal conductivity oxidation resistance, thermo 
mechanical properties and processability. Flexible and stable 
electromagnetic shielding materials can be fabricated with the aid of 
ionic liquid modified MWCNT [4,5].
Studies also reported in the area of dispersing other
 fillers like graphene, graphite oxide, graphene oxide, clay, layered 
double hydroxides, silica, carbon black etc. with the aid of ionic 
liquid. On mixing Graphene Oxide (GO) and ionic liquid, ILs had been 
effectively intercalated into the interlayer of GO, which was found to 
be able to raise the exfoliation degree of GO. It is found that both 
thermal stability and the thermal conductivity of Bromobutyl Rubber 
(BIIR) nanocomposites could be improved by incorporating the Ionic 
Liquids (ILs) modified graphene oxide (GO-ILs) [6].
Tribological study of functionalized graphene-IL nanocomposite
ultrathin lubrication films on Si substrates the promising
applications in the lubrication of micro/nanoelectromechanical
systems (MEMS/NEMS) [7]. It is possible to control the pore
size, electrical conductivity and mechanical robustness of the
polyurethane nanocomposite foam by incorporating it with
modified the graphene oxide using 1-methyl imidazole chloride
ionic liquid [8]. Boron Nitride Nanosheets (BNNS) are exfoliated
with the help of ionic liquid by physical adsorption on IL on BNNS
surfaces. Highly thermally conductive and electrically insulating
polymer nanocomposites can be prepares using this material [9].  
  Ionic liquid can be used as interfacial agent or surfactant
or organic modifier for layered double hydroxide in
polymer nanocomposites [10]. Ionic liquids were used as an
environmentally friendly material to improve the processability
of layered silicates containing polymer nanocomposites [11].
Zwitterionic Imidazolium-Based Ionic Liquid (ZIL) was used to
modify both cationic and anionic clay minerals. The ZIL was able
to penetrate into the interlayer space of clay and modified the
interfacial properties [12]. Studies have been reported on the role
of ionic liquid as an interfacial modifier for silica and as a cure
accelerator in polymer nanocomposites [13].
 In conclusion the use of ILs afforded not only high-yield,
mild, facile exfoliation of various fillers but also non-covalent
functionalization of fillers for multifunctional applications.
Merging processing techniques of nanocomposites with ionic
liquid for efficient dispersion of nanomaterials facilitates the
development of new, high performance materials.
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