Multifunctional Homopolymer Vesicles for Facile Immobilization of Gold Nanoparticles and Effective Water Remediation

Abstract

Homopolymers have been considered as a nonideal building block for creating well-defined nanostructures due to their fuzzy boundary between hydrophobic and hydrophilic moieties. However, this unique fuzzy boundary may provide some opportunities for fabricating functional nanomaterials. Presented in this paper is a pH-responsive multifunctional homopolymer vesicle based on poly[2-hydroxy-3-(naphthalen-1-ylamino)propyl methacrylate] (PHNA). This vesicle is confirmed to be an excellent supporter for gold nanoparticles (AuNPs) to facilitate the reduction reaction of 4-nitrophenol (4-NP). The pH-responsive vesicle membrane favors the effective embedding and full immobilization of AuNPs because it is kinetically frozen under neutral and basic environments, preventing AuNPs from aggregation. Meanwhile, there is a synergistic effect between the AuNPs and the supporter (PHNA vesicle). Due to the π–π interaction between the naphthalene pendants in every repeat unit of PHNA and the extra aromatic compounds, a substrate-rich (high concentration of 4-NP) microenvironment can be created around AuNPs, which can dramatically accelerate the AuNPs-catalyzed reactions. In addition, we proposed a method for more accurately determining the membrane thickness of rigid polymer vesicles from TEM images based on “stack-up” vesicles, which may overturn the measuring method commonly used by far. Moreover, proof-of-concept studies showed that those homopolymer vesicles may be used as a powerful adsorbent for effective water remediation to remove trace carcinogenic organic pollutants such as polycyclic aromatic hydrocarbons to below parts per billion (ppb) level at a very fast rate based on the π–π interaction between the naphthalene pendants in PHNA vesicle and polycyclic aromatic hydrocarbons. Overall, this multifunctional homopolymer vesicle provides an alternative insight on preparing effective recyclable AuNPs-decorated nanoreactor and powerful water remediation adsorbent