*Article* **Effect of Process Control Parameters on the Filtration Performance of PAN–CTAB Nanofiber/Nanonet Web Combined with Meltblown Nonwoven**

**Hyo Kyoung Kang 1,2, Hyun Ju Oh <sup>1</sup> , Jung Yeon Kim <sup>1</sup> , Hak Yong Kim 2,3,\* and Yeong Og Choi 1,\***

	- <sup>3</sup> Department of Nano Convergence Engineering, Jeonbuk National University, Jeonju 54896, Korea
	- **\*** Correspondence: dragon4875@gmail.com (H.Y.K.); yochoi@kitech.re.kr (Y.O.C.);
		- Tel.: +82-(0)63-270-2351 (H.Y.K.); +82-(0)31-8040-6084 (Y.O.C.)

**Abstract:** Nanofibers have potential applications as filters for particles with diameters <10 µm owing to their large specific surface area, macropores, and controllable geometry or diameter. The filtration efficiency can be increased by creating nanonets (<50 nm) whose diameter is smaller than that of nanofibers. This study investigates the effect of process conditions on the generation of nanonet structures from a polyacrylonitrile (PAN) solution containing cation surfactants; in addition, the filtration performance is analyzed. The applied electrospinning voltage and the electrostatic treatment of meltblown polypropylene (used as a substrate) are the most influential process parameters of nanonet formation. Electrospun polyacrylonitrile–cetylmethylammonium bromide (PAN–CTAB) showed a nanofiber/nanonet structure and improved thermal and mechanical properties compared with those of the electrospun PAN. The pore size distribution and filter efficiency of the PAN nanofiber web and PAN–CTAB nanofiber/nanonet web with meltblown were measured. The resulting PAN–CTAB nanofiber/nanonet air filter showed a high filtration efficiency of 99% and a low pressure drop of 7.7 mmH2O at an air flow rate of 80 L/min. The process control methods for the nanonet structures studied herein provide a new approach for developing functional materials for air-filtration applications.

**Keywords:** nanonet; polyacrylonitrile; surfactant; electrospinning; meltblown; nanofiber/nanonet
