ARTICLE Investigation of improved dielectric and thermal properties of ternary nanocomposite PMMA/MXene/ZnO fabricated by in-situ bulk polymerization Yasir Ul Haq 1 | Imran Murtaza 1 | Sadaf Mazhar 2 | Naeem Ahmad 1 | Awais A. Qarni 3 | Zeeshan Ul Haq 4 | Shahid A. Khan 2 | Mahmood Iqbal 5 1 Spintronics Laboratory, Department of Physics, International Islamic University, Islamabad, Pakistan 2 Institute of Chemical Sciences, University of Peshawar, Peshawar, Pakistan 3 Department of Chemistry, Chemnitz Technical University, Chemnitz, Germany 4 Department of Physics, University of Peshawar, Peshawar, Pakistan 5 Pakistan Council of Scientific and Industrial Research Laboratories Complex, Peshawar, Pakistan Correspondence Imran Murtaza, Spintronics Laboratory, Department of Physics, International Islamic University Islamabad 44000, Pakistan. Email: imran.murtaza@iiu.edu.pk, imran. murtaza11@gmail.com Abstract Electric power system applications demand for high-temperature dielectric materials. The improved performance of polymer nanocomposites requires improvement in their thermal conductivity & stability, dielectric stability and processing technique. However, they often lose their dielectric properties with a rise in temperature. Here, we offer a solution by incorporating electrically conducting material (MXene) and semiconducting inorganic nanoparticles (ZnO NPs) into an insulating PMMA polymer matrix to maintain high dielec- tric constant, both at the room and high temperature. Therefore, to achieve desirable thermal and dielectric properties is the main objective of the present study based on the homogeneous distribution of the nanofillers by in-situ bulk polymerization assisted by strong sonication in the corresponding polymer. The introduction of MXene and ZnO NPs into the PMMA not only acquires a substantial increment in the dielectric constant, to attain a value 437, with minimum energy loss of 0.36 at 25 Hz, but also improves the thermal conduc- tivity of PMMA up to 14 times by causing the reduction of thermal resistance, which is actually responsible for the poor thermal conductivity of amorphous pure PMMA polymer. More importantly, hybrid PMMA/4:2 wt% MXene:ZnO nanocomposite leads to an excellent thermal stability. Moreover, further char- acterization of the synthesized nanocomposites by FTIR, SEM and XRD leads to the evaluation of strong interaction of ternary components with PMMA matrix. KEYWORDS batteries and fuel cells, composites, dielectric properties, nanoparticles, nanowires and nanocrystals, structure-property relationships 1 | INTRODUCTION Since polymers are lightweight, convenient to transform into any shape and economical, the polymer matrix serves as a substrate in many electronic and computer components. However, polymers, owing to their amor- phous and heat-insulating nature with lower thermal conductivity, disturb the efficiency of the circuits used in electronic packaging, transformers and many other applications. [1–6] Therefore, the electronic industry is Received: 10 September 2019 Revised: 2 February 2020 Accepted: 16 February 2020 DOI: 10.1002/app.49197 J Appl Polym Sci. 2020;e49197. wileyonlinelibrary.com/journal/app © 2020 Wiley Periodicals, Inc. 1 of 16 https://doi.org/10.1002/app.49197