Nanoscale Res Lett (2009) 4:420–430 DOI 10.1007/s11671-009-9262-5 N A N O E X P R E S S Inﬂuence of Nanogels on Mechanical, Dynamic Mechanical, and Thermal Properties of Elastomers Suman Mitra Æ Santanu Chattopadhyay Æ Anil K. Bhowmick Received: 6 October 2008 / Accepted: 27 January 2009 / Published online: 13 February 2009 to the authors 2009 Abstract Use of sulfur crosslinked nanogels to improve various properties of virgin elastomers was investigated for the ﬁrst time. Natural rubber (NR) and styrene butadiene rubber (SBR) nanogels were prepared by prevulcanization of the respective rubber lattices. These nanogels were characterized by dynamic light scattering, atomic force microscopy (AFM), solvent swelling, mechanical, and dynamic mechanical property measurements. Intermixing of gel and matrix at various ratios was carried out. Addition of NR gels greatly improved the green strength of SBR, whereas presence of SBR nanogels induced greater thermal stability in NR. For example, addition of 16 phr of NR gel increased the maximum tensile stress value of neat SBR by more than 48%. Noticeable increase in glass transition temperature of the gel ﬁlled systems was also observed. Morphology of these gel ﬁlled elastomers was studied by a combination of energy dispersive X-ray mapping, trans- mission electron microscopy, and AFM techniques. Particulate ﬁller composite reinforcement models were used to understand the reinforcement mechanism of these nanogels. Keywords Nanogels Mechanical properties Elastomers Gels Thermal properties Electronic supplementary material The online version of this article (doi:10.1007/s11671-009-9262-5) contains supplementary material, which is available to authorized users. S. Mitra S. Chattopadhyay A. K. Bhowmick (&) Rubber Technology Centre, Indian Institute of Technology, Kharagpur 721302, India e-mail: anilkb@rtc.iitkgp.ernet.in 123 Introduction Virgin polymers, especially elastomers have inherently low stiffness and strength. In order to overcome these obvious limitations and to expand their applications in different ﬁelds, particulate ﬁllers, such as carbon black, silica, glass, calcium carbonates, carbon nanotubes, nano clays etc. are often added to polymer. Particulate ﬁllers modify physical and mechanical properties of polymers in many ways. Use of carbon black for improving reinforcement properties of an elastomer has been studied extensively in numerous investigations [1, 2]. Amongst the nonblack ﬁllers, mostly silica provides the best reinforcing properties [3]. In the last decade, it has been shown that dramatic improvements in mechanical and other properties can be achieved by incorporation of a few weight percentages (wt%) of inor- ganic exfoliated clay minerals consisting of mostly layered silicates in polymer matrices [4–10]. These are better known as polymer nanocomposites. Similar enhancements in various properties have also been reported with other types of nanoﬁllers e.g. multiwalled carbon nanotubes and layered double hydroxides [11, 12]. Although not strictly categorized as ﬁller, use of gels to improve various physical properties of elastomers, with an added advantage of superior processability, can be found in the prevailing literature [13–15]. Kawahara et al. [16] have reported the effect of gel on green strength of natural rubber. In most of the above work, the authors have used physically crosslinked or entangled network gels. How- ever, our recent preliminary work with chemically crosslinked nanogels and quasi-nanogels has revealed that addition of these gels leads to a considerable improvement in processability, mechanical, and dynamic mechanical properties of virgin natural rubber (NR) and styrene buta- diene rubber (SBR) [17–19]. Optimization of these