Structure–property relationship of SELF-sustained homogeneous ternary nanocomposites: Key issues to evaluate properties of rrP3HT wrapped MWNT dispersed in TPU

An interesting correlation between nature of wrapping, wrapping thickness and crystallinity of regioregular poly(3-hexyl thiophene) (rrP3HT) wrapped multi-walled nanotube (MWNT) arises due to different loading of rrP3HT and their combined effect on the properties of a ternary system prepared by uniform dispersion of wrapped CNT into thermoplastic polyurethane (TPU) are highlighted in the article. Data accumulated through different techniques demonstrate that 2.5 wt.% of rrP3HT with 0.5 wt.% of MWNT can be the ideal ratio of filler to achieve highest properties in these stable self-sustained homogeneous composites. Wrapping of rrP3HT on the wall of CNT through π–π and/or CH–π interaction is ascertained from shifting in peak position and Iasym/Isym ratio of CC bond of rrP3HT in FTIR spectroscopy. Strong quenching of fluorescence intensity of rrP3HT in composite further support π–π interaction between rrP3HT and CNTs. SEM micrograph of rrP3HT/TPU blends suggest uniform globular dispersion of polythiophene into TPU matrix without any separate phase domain and addition of CNTs considerably reduce globule size. Single Tg(∼−40 °C, DMA, DSC, TMA) clearly ascertain the miscibility of composite. An ‘order to order transition’ through coil to rod transformation leads to strong, sharp red shifting (∼150 nm shift compared to pristine rrP3HT) in emission peaks of rr-poly (3-hexylthiophene) in blends. Further red shifting and highest quenching is observed in case of 2.5% rrP3HT loaded ternary system whereas blue shifting and quenching in case of 0.5 wt.% (non-uniform wrapping) and 5 wt.% (agglomerates) rrP3HT loading.