Electrospinning as a new technique to control the crystal morphology and molecular orientation of polyoxymethylene nanofibers

J Am Chem Soc. 2008 Nov 19;130(46):15460-6. doi: 10.1021/ja804185s. Epub 2008 Oct 25.

Abstract

Electrospinning is widely accepted as a simple and versatile technique for producing nanofibers. The present work, however, introduces a new concept of the electrospinning method for controlling the crystal morphology and molecular orientation of the nanofibers through an illustration of a case study of polyoxymethylene (POM) nanofibers. Isotropic and anisotropic electrospun POM nanofibers are successfully prepared by using a stationary collector and a rotating disk collector. By controlling the voltage and the take-up velocity of the disk rotator, the morphology changes between an extended chain crystal (ECC) and a folded chain crystal (FCC) as clarified by a detailed analysis of the X-ray diffraction and polarized infrared spectra of the POM nanofibers. Herman's orientation function and dichroic ratio lead us to a schematic conclusion--that (i) molecular orientation is parallel to the fiber axis in both isotropic and anisotropic POM nanofibers, (ii) a single nanofiber consists of a nanofibril assembly with a size of 60-70 A and tilting at a certain degree, and (iii) the higher the take-up velocity, the smaller the nanofibril under the (9/5) helical structure of the POM chains. It should be emphasized here that the electrospinning method is no longer a single nanofiber producer but that it can be applied as a new instrument to control the morphology and chain orientation characteristics of polymer materials, opening a new research field in polymer science where we can understand the relationship between structure at the molecular level and the properties and performance at the macroscopic level.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallization
  • Electrons*
  • Microscopy, Electron, Scanning
  • Nanoparticles / chemistry*
  • Nanoparticles / ultrastructure*
  • Resins, Synthetic / chemistry*
  • Spectroscopy, Fourier Transform Infrared

Substances

  • Resins, Synthetic
  • delrin