In situ preparation, morphology and electrical properties of carbon nanofiber/polydimethylsiloxane nanocomposites Nabarun Roy • Anil K. Bhowmick Received: 24 April 2011 / Accepted: 12 July 2011 / Published online: 26 July 2011 Ó Springer Science+Business Media, LLC 2011 Abstract For the first time, a series of carbon nanofiber (CNF)/polydimethylsiloxane(PDMS)-based nanocompos- ites was prepared using in situ polymerization technique by critical manipulation of factors, such as method of prepa- ration and chemical modification of filler. Quantification of the degree of dispersion was done by introducing a dis- persion degree parameter. Extent of dispersion was found to improve by amine modification of CNFs. Electrical conductivity was found to undergo profound increase when compared with that of the insulating base polymer. Amine- modified CNF-based nanocomposites showed percolation threshold at lower filler loading compared with unmodified CNF-based nanocomposites. These results of electrical properties measurements were correlated with the results of TEM analysis. Introduction Recent developments in material science involve a novel and attractive approach of incorporation of nanoparticles into polymers, since this facilitates the development of new materials by exploring synergistic effects [1, 2]. The intriguing feature of these advanced materials includes improved thermal, mechanical, electrical, and selective permeation properties [3–5]. Although traditional com- posites contain significant amount of filler, dramatic improvement in properties is observed for low loadings of various nanofillers [6–9]. These improvements in proper- ties are achieved by exploiting several factors, such as degree of dispersion, interface chemistry, and nanoscale morphology. Of the carbon-based fillers, carbon nanotubes and carbon nanofibers (CNFs) exhibit intrinsic mechanical and elec- trical properties [10, 11]. However, due to high specific surface area and energy, these nanofillers tend to aggregate, which makes it very difficult to disperse homogeneously in the host polymer matrix. Surface functionalization is one of the way-outs which significantly improves filler dispersion [12, 13]. Polydimethylsiloxane (PDMS), on the other hand, possesses several virtues such as low temperature flexibil- ity, high thermal stability, biocompatibility, etc. However, its poor electrical properties limit its gamut of applications. Thus, the main aim of this study is to improve the electrical properties of these insulating elastomers. Nanocomposite preparation facilitates improvement in various properties, provided proper dispersion of the filler is achieved. Extensive literature survey reveals that no work has been done till date on CNF/PDMS nanocomposites. The probable reason for this is the huge surface energy differ- ence of PDMS and CNF. PDMS is a semiorganic polymer with very low surface energy (*19.6 mJ/m 2 ) [14], whereas CNF has an appreciably high surface energy of 145–165 mJ/m 2 [15]. This restricts homogeneous disper- sion of nanofibers in the polymer matrix. Thus, preparation of CNF/PDMS nanocomposites is itself challenging and novel. Moreover, the method of in situ preparation of nanocomposite through anionic ring opening polymeriza- tion is completely new. In this article, it is shown for the first time how the in situ preparation of nanocomposite affects the extent of dispersion in comparison with the conventional ex situ prepared nanocomposites. Further- more, the effect of filler functionalization on properties of N. Roy  A. K. Bhowmick (&) Rubber Technology Centre, Indian Institute of Technology, Kharagpur 721302, India e-mail: anilkb@rtc.iitkgp.ernet.in; director@iitp.ac.in A. K. Bhowmick Indian Institute of Technology, Patna 800013, India 123 J Mater Sci (2012) 47:272–281 DOI 10.1007/s10853-011-5795-y