Ultrasound assisted solvent free intercalation of montmorillonite with PEG1000: A new type of organoclay with improved thermal properties

•PEG1000 intercalated MMT composites were prepared by solvent free ultrasonication.•The thermal storage capacity is 104.8Jg−1 in the temperature range 32.9–43.0°C.•Increased heat-transfer area is provided by the numerous clay particles.•Potential for use in new thermal insulation products.