The spatial distribution of nanoparticles in a particular host polymer matrix can be improved by using brush coated nanoparticles. In this work we have grafted styrene-acrylonitrile (SAN) onto the surface of graphene oxide (GO) and investigated as to how the demixing temperature, morphology and volume cooperativity of PMMA/SAN blends are influenced. Grafting of polymer chains on the surface of nanoparticles usually involves the use of large amounts of solvents, many which are detrimental to the environment besides involving cumbersome processes. SAN-g-GO was prepared by a robust solvent-free strategy wherein the cyano group in SAN was replaced by oxazoline groups during melt mixing in the presence of zinc acetate and ethanol amine. These newly created oxazoline groups reacted with the COOH group of GO under melt extrusion resulting in grafting of SAN on the surface of GO sheets. The effect of SAN-g-GO nanoparticles on the demixing, local segmental motions and morphology evolution for different annealing times was carefully investigated in a classical LCST system, PMMA/SAN blend, using melt rheology, modulated DSC and AFM, respectively. The changes in viscoelastic behavior in the vicinity of demixing are investigated systematically for the control, and blends with GO and SAN-g-GO. Various models were used to gain insight into the spinodal decomposition temperatures of the blends. Interestingly, the demixing temperature determined rheologically and the spinodal decomposition temperature increased significantly in the presence of polymer grafted nanoparticles in comparison to the control and blends with GO. The evolution of the morphology, interfacial driven coarsening as a function of temperature and the localization of nanoparticles were assessed using atomic force microscopy. The cooperatively re-arranging regions estimated from calorimetric measurements begin to suggest enhanced dynamic heterogeneity in the presence of GO and SAN-g-GO in the blends. Taken together, our study reveals that the solvent-free approach of grafting SAN onto GO delays demixing, suppresses coalescence and alters cooperative relaxation in PMMA/SAN blends.

Polymer blending is an effective method which can be used to fabricate new versatile materials with enhanced properties. Blending of two polymers can either result in a miscible or immiscible...

Innovations in the telecommunication industry and its growth in the direction of wireless technologies has effectuated electromagnetic interference as its ramification. The progressive miniaturization of gadgets has made circuitry complex...

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Polymer-based composites have emerged as promising candidates for microwave attenuation. It is now understood that, in order to enhance this attenuation, the amount of functional nanoparticles in the system has to be very high. However, this is limited by the processing challenges because the mixing parameters affect the way the nanoparticles are dispersed in a polymer nanocomposite. Although it is possible to achieve good mixing with the help of current state-of-art technology, the maximum amount of nanoparticles that can be incorporated is limited by several factors. Herein, a unique strategy (nanoinfiltration) is described to increase the filler concentration based on the dynamics of polymer chains in the presence of a solvent that is reported for increasing the filler concentration. Upon spin coating of a polymer solution containing well-dispersed nanoparticles, the solvent causes the polymer to swell, thereby increasing the available free volume where the nanoparticles can get trapped. Interesting morphologies were observed when nanoparticles of different shapes [spherelike Fe 3 O 4 , rodlike multiwalled carbon nanotubes (MWCNTs), and sheetlike graphene oxide (GO) and also hybrid structures like reduced graphene oxide, rGO−Fe 3 O 4 and rGO−MoS 2 were spin-coated. This establishes a strong correlation between the morphology of the nanoparticles and the free volume and characteristic length of the polymer chain. This approach was extended to design conducting nanocomposites in order to explore them for EMI shielding applications. Herein, we have employed nanoinfiltration to embed different nanoparticles into a composite of recycled polystyrene with multiwalled carbon nanotube (PS− MWCNT). It was observed that the shielding effectiveness of PS−MWCNT was enhanced up to −35 dB after being subjected to nanoinfiltration with rGO−MoS 2 . In order to evaluate the efficacy of this strategy, PS−MWCNT was sandwiched between two sheets of porous poly(vinylidene fluoride) containing rGO−MoS 2 . In doing so, a sharp decrease in the value of the EMI shielding effectiveness was observed. This hence suggests that nanoinfiltration proves to be a useful tool to enhance the radiation shielding property of conducting nanocomposites.