Structure–Property Relationships of Benzenetrisamide Derivatives as Polypropylene Nucleating Agents: Experimental Evaluation and Predictive Method

Benzene-trisamide (BTA) derivatives have been investigated as efficient nucleating agents for polypropylene. However, a fundamental understanding of their structure–property relationships was lacking. In this work, five side-chain isomeric BTA derivatives were designed, which feature an N -phenylamide core with isomeric side chains: tert -butyl (NA-Te), sec -butyl (NA-Di), isobutyl (NA-Th), cyclobutyl (NA-Cy), n -butyl (NA-Nb). Derivatives were successfully synthesized with structure confirmed by 1 H nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared spectrometer (FTIR). Differential scanning calorimetry (DSC) results showed that all five structures enhanced the crystallization temperature ( T c ) of iPP. Notably, NA-Te and NA-Di exhibited the highest nucleation effectiveness, increasing T c by 14.6 and 10.0 °C, respectively. Furthermore, they reduced the haze of iPP by 74.9% and 67.7%, demonstrating their outstanding optical clarity. The experimental results demonstrated that slight modifications to the side-chain structure led to a marked divergence in the nucleation efficiency. The structure–property relationship of NAs in iPP was elucidated by examining the interactions between NAs and iPP chains through Materials Studio (MS). It was found that NA-Te and NA-Di exhibited stronger interaction compared to other derivatives, which explains their enhanced nucleation efficiency at the molecular level. The simulation results were validated by rheological test, with the NA-Te and NA-Di showing slightly increased complex viscosity over the other three derivatives. The predictive method for evaluating structure–property relationships was proposed and further validated by its application to three new BTA derivatives with C5 side chains. This research enriched the nucleation mechanism of BTA derivatives and offers crucial guidelines for developing high-efficiency polypropylene nucleating agents.