**1. Introduction**

Solution blow spinning (SBS) is a rising preparation technique to produce polymer films with ultrafine fibers and high specific surface area [1]. A regular SBS apparatus consists of a high velocity air source, a syringe pump, a concentric nozzle system, and a collector [2]. The polymer solution in the inner nozzle is elongated into fine fiber by the surrounding high velocity airflow in the outer nozzle. Moreover, because SBS uses high velocity airflow to form fibers, there is no requirement for the conductivity of the solution compared to electrospinning. As the solvent rapidly evaporates in the process of moving towards the collector, ultrafine fibers deposited and formed a nanofibrous film on the collector [3]. The SBS has served a wide range of purposes that include biosensors, the aerospace industry, impurity removers, and wearable electronics [4]. The development of nanofiber films for food packaging using SBS, however, has undergone little research. For the present, the utilization of nanofiber film in food packaging is primarily manufactured by the electrospinning method [5–9]. Nonetheless, previous works show that the fiber production efficiency of SBS could be much higher than electrospinning. Tandon et al. [10] found that SBS was three times more efficient in fiber production than electrospinning; and

**Citation:** Yang, Z.; Shen, C.; Zou, Y.; Wu, D.; Zhang, H.; Chen, K. Application of Solution Blow Spinning for Rapid Fabrication of Gelatin/Nylon 66 Nanofibrous Film. *Foods* **2021**, *10*, 2339. https://doi.org/ 10.3390/foods10102339

Academic Editor: Christos Ritzoulis

Received: 14 September 2021 Accepted: 28 September 2021 Published: 30 September 2021

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in the study of Sett et al. [11], the fiber productivity of SBS was even up to 30 times higher than that of electrospinning. Shen et al. [12] also found that the SBS process could reach a rapid feed rate of 3 mL/h, while the feed rate of the electrospinning is generally between 0.1 mL/h and 0.6 mL/h. In this regard, the SBS technology has demonstrated its promising potential for the fast production of large area nanofiber film for food packaging.

Gelatin (GA) is a single-stranded protein obtained by hydrolysis of collagen, with favorable biocompatibility, biodegradability and nontoxicity, and has been utilized extensively in the food, pharmaceutical and photographic industries [13–15]. However, due to the solubility in aqueous solution and poor mechanical properties, gelatin nanofibers usually require modification by chemical cross-linking agents [16,17]. Bigi et al. [18] investigated the mechanical and swelling properties of glutaraldehyde (GTA) crosslinked gelatin films, and found that the use of GTA allowed to regulate the physical-chemical properties of gelatin films. But the residue and cytotoxicity of chemical agents have limited its application in the food field [19].

Various studies have shown that many synthetic polymers such as poly(caprolactone) (PCL), poly(glycolic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) can be used with natural polymers to produce polymer composites with improved performance [20–24]. Among these synthetic polymers, nylon 66 (polyamide 66, PA66) is a multifunctional synthetic thermoplastic polymer broadly used in textiles, parachutes, biomedical fields, and functional materials [25]. It was reported that PA66 has been successfully used to modify epoxy resins to achieve tensile toughness enhancement [26], however there has been limited work related to the use of PA66 for the modification of natural polymers, especially gelatin. Owing to its anti-abrasion resistance, high mechanical strength, light weight, relatively low cost and, very importantly, biological safety [27–31], PA66 can be used as a potential modification material for gelatin.

In this work, SBS was used to rapidly fabricate GA/PA66 composite nanofiber films to address the need for food packaging materials to be prepared on a large scale. The feasibility of PA66 as the modifier to enhance comprehensive performance of gelatin in mechanical properties and the ability to resist dissolution was evaluated. The morphology, diameter distribution, molecular interaction, crystal structures, thermal stability, mechanical strength, water contact angle (WCA) and water vapor permeability (WVP) of the GA, GA/PA66 and PA66 films were characterized. In addition, the prospects of SBS for rapid preparation of food packaging are discussed.
