Effect of Filler Dimensionality on the Order-Disorder Transition of a Model Block Copolymer Nanocomposite

Content Provider	Semantic Scholar
Author	Jain, Anurag Gutmann, Jochen Stefan Zhang, Yuanming Gruner, Sol M. Wiesner, Ulrich B.
Abstract	Introduction. The majority of commercially available polymeric materials consist of a polymer matrix whose properties are augmented by the addition of filler materials. Representative filler materials consist of carbon black or silicates.1,2 They can have spherical, rodlike, or platelike geometry, the latter derived, for example, from clay nanoparticles.2 Typically the fillers are used to enhance the properties of the polymer matrix, such as tensile strength, modulus, or heat distortion temperature. While in the past large fillers have often been used, industrial as well as academic research is currently focusing on nanocomposites.3 As a result of the large surface area of nanoscopic fillers, very small amounts can induce significant changes in polymer properties. As an example, in ref 4, it has been shown that for a styrene methylvinyloxazoline copolymer matrix, the addition of as little as 5 wt % modified montmorillonite clay nanoparticles increases the tensile modulus 1.4 times. Systematic theoretical studies of thermodynamic and dynamic properties of block-copolymer-based nanocomposites have only been conducted recently owing to their complexity.5-11 In these simulations, the filler particles are of an ideal nature; i.e., they are completely dispersed, their geometry is very well-defined, and their surface is often taken to be either completely wettable or nonwettable by the polymer matrix. These assumptions are very difficult to realize experimentally, as it is, for example, very challenging to exfoliate the lamellae of clay type fillers completely. Thus, there is clearly a need for a model system that allows the creation of nanoscale filler materials with well-defined geometries and surface potentials. We have recently shown that the block copolymer assisted sol-gel synthesis of silica type materials allows an unprecedented control over the shape and size of the resulting nanoparticles.12-14 Furthermore, the surface of the silica particles is decorated with polymer chains as a consequence of their synthesis,13 resulting in a controlled surface potential. In the present study we use the aforementioned approach to synthesize nanoobjects with spherical, rodlike, and platelike geometry and a layer of polyisoprene hairs on their surface. These nano-objects are used as fillers in a poly(styrene-b-isoprene) block copolymer (PS-b-PI) matrix to generate model nanocomposites. In this model system, the filler particles have a well-controlled dimensionality and are preferentially wetted by the polyisoprene block of the matrix copolymer. In this first report the influence of filler dimensionality on the order-disorder phase transition of the matrix block copolymer is investigated.
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Alternate Webpage(s)	http://bigbro.biophys.cornell.edu/publications/168_Jain_2002.pdf
Language	English
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Subject Keyword	Carbon Black Clay animation Copolymer Distortion Experiment Filler (substance) GNU nano Hair Modulus robot Montmorrillonite Nanocomposite Phase Transition Physical object Polymer Silicon Dioxide Simulation Sol-gel Solution Dosage Form Star filler Styrene Styrene:MCnc:Pt:Bld:Qn The Matrix Thermodynamics isoprene tensile strength
Content Type	Text
Resource Type	Article