Preparation of Solution Blown Polyamic Acid Nanofibers and Their Imidization into Polyimide Nanofiber Mats.

Jing Li,Guocheng Song,Yan Wang,Jing Zhu,Junrong Yu,Zuming Hu

doi:10.3390/nano7110395

Abstract

Solution blow spinning (SBS) is an innovative process for spinning micro/nanofibers. In this paper, polyamic acid (PAA) nanofibers were fabricated via a SBS apparatus and then imidized into polyimide (PI) nanofibers via thermal process. The morphology and diameter distributions of PAA nanofibers were determined by scanning electron microscope (SEM) and Image Tool software, the processing parameters, including PAA concentration, solution feeding rate, gas pressure, nozzle size, and receiving distance were investigated in details. The fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical changes in the nanofibers after thermal imidization. The results showed that the solution concentration exhibited a notable correlation with spinnability, and the formation of bead defects in PAA nanofibers. Solution feeding rate, gas pressure, nozzle size, and receiving distance affected nanofiber production efficiency and diameter distribution. The average diameters of fibers produced ranged from 129.6 to 197.7 nm by varying SBS parameters. Precisely, PAA nanofibers with good morphology were obtained and the average diameter of nanofibers was 178.2 nm with optimum process parameter. After thermal imidization, the PI nanofibers exhibited obvious adhesion morphology among interconnected fibers, with an increased average diameter of 209.1 nm. The tensile strength of resultant PI nanofiber mat was 12.95 MPa.

Highlights

Novel nanofiber techniques have gained wide interest, since nanofibers possess extraordinary structure features, novel performance, and exhibit tremendously potential application [1]
ES has been densely adopted for continuously making polymeric nanofibers [5], some drawbacks still remain, for instance, the requirement of collector’s conductivity and the safety issue caused by high voltage, it suffers from a relatively low fiber production efficiency, these restrictions prohibit it from being applied in industrialization [6]
The processing parameters are optimized, the effects of polymer concentration, solution feeding rate, gas pressure, nozzle inner diameter, and receiving distance on the nanofibers morphology and diameter distribution of resultant polyamic acid (PAA) nanofibers are systematically evaluated by means of scanning electron microscope (SEM) and image tool analysis software

Summary

Introduction

Novel nanofiber techniques have gained wide interest, since nanofibers possess extraordinary structure features, novel performance, and exhibit tremendously potential application [1]. SBS process is similar to that used in conventional melt blow spinning, it only requires a simple apparatus, a homogeneous polymer solution in a volatile solvent, and a high-velocity gas source [14]. During the SBS process, the solution streams are stretched to ultrathin jets by high-velocity gas flow from outer nozzle and is solidified into nanofibers after solvent evaporation [16].

Results

Conclusion