*Article* **Spray-Assisted Interfacial Polymerization to Form CuII/I@CMC-PANI Film: An Efficient Dip Catalyst for A<sup>3</sup> Reaction**

**Zhian Xu 1, Liang Xiao 1, Xuetao Fan 1, Dongtao Lin 1, Liting Ma 2, Guochao Nie 2,\* and Yiqun Li 1,\***


**Abstract:** A novel and interesting method for the preparation of carboxymethylcellulose–polyaniline film-supported copper catalyst (CuII/I@CMC-PANI) has been developed via spray-assisted interfacial polymerization. Using copper sulfate as an initiator, spraying technology was introduced to form a unique interface that is perfectly beneficial to the polymerization of aniline monomers onto carboxymethylcellulose macromolecule chains. To further confirm the composition and structure of the as-prepared hybrid film, it was systematically characterized by inductively coupled plasma (ICP), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis (TGA) techniques. The Cu content in the fresh CuII/I@CMC-PANI film was determined to be 1.805 mmol/g, and spherical nanoparticles with an average size of ca. 10.04 nm could be observed in the hybrid film. The CuII/I@CMC-PANI hybrid film was exerted as a dip catalyst to catalyze the aldehyde–alkyne–amine (A3) coupling reactions. High yields of the products (up to 97%) were obtained in this catalytic system, and the catalyst could be easily picked up from the reaction mixture by tweezers and reused for at least six consecutive runs, without any discernible losses in its activity in the model reaction. The dip catalyst of CuII/I@CMC-PANI, with easy fabrication, convenient deployment, superior catalytic activity, and grea<sup>t</sup> reusability, is expected to be very useful in organic synthesis.

**Keywords:** interfacial polymerization; spraying method; carboxymethylcellulose; polyaniline; copper catalyst; dip catalyst; A<sup>3</sup> reaction
