Interfacial Design via Structural Similarity in Polyethylene Terephthalate/Carbon Nanotube Composites: Experimental and Computational Collaborative Approach

In this study, to maximize the interfacial interaction between polyethylene terephthalate (PET) and carbon nanotube (CNT), bis (2‐hydroxyethyl) terephthalate (BHET) was introduced onto multi‐walled carbon nanotube (MWCNTs) as an interfacial design strategy based on structural similarity (MWCNT‐BHETs). Experimental analysis confirmed that the MWCNT‐BHETs exhibited superior dispersibility within the PET matrix and acted as an effective nucleating agent, increasing the crystallization temperature and reducing supercooling. Notably, at 1.0 wt% loading, the tensile strength and initial modulus of the PET composite film improved by 28.8% and 15.1%, respectively, significantly outperforming acid‐treated MWCNTs. To elucidate the reinforcement mechanism, molecular dynamics simulations were performed. The results demonstrated that while pristine CNTs inherently exert an interfacial confinement effect, BHET functionalization on the CNTs amplifies this behavior, leading to a more pronounced reduction in the mean square displacement (MSD) of PET chains. Interestingly, the suppression of chain mobility was maximized as the number of BHET repeating units increased from 1 to 3; however, a saturation effect was observed between 3 and 5 units, with no further change in MSD beyond this range. This suggests a nonlinear correlation between functional group length and mechanical enhancement, highlighting that optimizing interfacial chain length is more critical than simply increasing the degree of functionalization. These insights provide sophisticated guidelines for designing high‐performance polymer composites through a collaborative approach of experimental and computational analysis.