β-Cyclodextrin Encapsulation of Anthracene-Based Polymer: A Versatile Approach for Photoluminescence Recovery and Improved Thin Film Performance

In this study, we present the synthesis of a novel host-guest polyrotaxane (PR1) using a microwave-assisted threading approach. The polyrotaxane structure involves the encapsulation of an anthracene-based conjugated polymer (P1) within β-cyclodextrin (β-CD) cavities. The successful formation of PR1 and P1 was confirmed using various spectroscopic and thermal techniques. Optimized geometry and vibrational frequencies of the polymer P1 conducted using DFT calculations at the DFT/B3LYP/6-311+G(d) level of theory showed good agreement with experimental results. Physicochemical and electrical properties of PR1 and the free polymer P1 revealed significant improvements resulting from the encapsulation process. Particularly, enhanced solubility in DMF and DMSO and processability, improved thermal stability, surface homogeneity, and smoothness in PR1 compared to the free polymer. Additionally, the encapsulation process led to an enhanced redox potential of PR1 in comparison to the free polymer. Interestingly, the photoluminescence of thin films of P1 was found to be quenched due to a phenomenon known as aggregation caused quenching (ACQ). However, the encapsulation of the polymer using β-CD rings reduced the formation of aggregates, effectively suppressing the ACQ process. This resulted in the recovery of photoluminescence. Notably, the charge carrier mobility of the encapsulated polymer was maintained at a similar order of magnitude.