Intramolecular Cyclization-Induced Self-Assembly of Poly(amic acid) for Rapid Adsorption of Victoria Blue R

Abstract

Rapid industrialization has led to the massive release of dye pollutants, posing a significant risk to aquatic ecosystems and human health. Polymeric nanosheets are highly attractive candidates for water remediation due to their abundant, accessible active sites. Herein, an intramolecular cyclization-induced self-assembly (ICISA) strategy is employed to construct polymeric nanosheets on the basis of reactivity of an amphiphilic poly(amic acid) (PAA) for rapid cationic dye adsorption. Upon thermal annealing, an intramolecular cyclization reaction occurs to generate polyimide (PI) segments in the polymer backbone, affording poly(amic acid-stat-imide) (P(AA-stat-I)), which enhances polymer solvophobicity and crystallinity, inducing ICISA of P(AA-stat-I) and leading to the formation of nanosheets. Benefiting from their multilayered structure and rich functional groups of carboxyl and amide, the nanosheets demonstrate ultrafast and efficient adsorption toward Victoria Blue R in water, with over 92.90% removal achieved in only 2 min and an adsorption capacity of up to 188.98 mg g–1. Mechanistic investigations reveal that the adsorption process is driven synergistically by electrostatic interaction, hydrogen bonding, and π–π stacking. This study employs an ICISA strategy for the versatile fabrication of polymeric nanosheets for high-performance adsorption of cationic dyes.