Electrospun Nanofibers

Mehdi Afshari

• Publisher: Woodhead Publishing
• Year: 2016
• Topic: Technology & Engineering
• eBook ISBN:
  9780081009116
• Subtopic: Industrial Engineering
• Index: Technology & Engineering

Electrospun Nanofibers covers advances in the electrospinning process including characterization, testing and modeling of electrospun nanofibers, and electrospinning for particular fiber types and applications. Electrospun Nanofibers offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science. Electrospinning is the most commercially successful process for the production of nanofibers and rising demand is driving research and development in this field. Rapid progress is being made both in terms of the electrospinning process and in the production of nanofibers with superior chemical and physical properties. Electrospinning is becoming more efficient and more specialized in order to produce particular fiber types such as bicomponent and composite fibers, patterned and 3D nanofibers, carbon nanofibers and nanotubes, and nanofibers derived from chitosan. - Provides systematic and comprehensive coverage of the manufacture, properties, and applications of nanofibers - Covers recent developments in nanofibers materials including electrospinning of bicomponent, chitosan, carbon, and conductive fibers - Brings together expertise from academia and industry to provide comprehensive, up-to-date information on nanofiber research and development - Offers systematic and comprehensive coverage for academic researchers, industry professionals, and postgraduate students working in the field of fiber science

1

Introduction

M. Afshari E. I. DuPont de Nemours, Richmond, VA, United States

Abstract

This chapter reviews briefly the history of electrospinning and recent accelerated rate of research in this field. We also summarize topics discussed in each chapter of the book.

Keywords

Electrospinning; Electrospun; Nanofiber

It has been a long-lasting dream of humans to control changes in the world around us and accept those that satisfy our needs. There has been an enormous amount of progress in material science and producing materials with different chemistries, structures, and properties from natural and synthetic materials by starting from small molecules and creating macromolecules or polymers. As Feynman [1] mentioned in 1959, “there's plenty of room at the bottom.” Basically, he introduced the nanotechnology and importance of the structure of materials that expanded to almost all aspects of science (physics, chemistry, biology, engineering, and materials) and controls changes at the nanoscale, which led to innovative developments in the past several decades. The subjective definition of nanomaterials is materials that range in size from atoms, or molecule size, up to 500 nm. Nanotechnology dramatically influenced developments in the field of material science. The ever-growing library of nanostructures with variable sizes, shapes, and compositions has opened up great opportunities for the design of functional materials [2]. Control material structure at the molecular level has been enabled by the innovative nanoscale manipulation that is critical for improving the performance of materials [3,4].

Some of the unique advantages of nanomaterials are high surface area, flexibility in surface functionality, and highly porous membranes with excellent interconnectivity that create enhancements in various fields such as biomedical, energy harvest and storage, electronics (supercapacitors and nanosensors), healthcare and cosmetics, protective clothing, environmental protection, and filtration. In the field of nanotechnology, nanofibers, nanoparticles, nanotubes, and nanowires are the most investigated forms of materials. Nanofibers, due to their high surface area, aspect ratio, flexibility, etc., have attracted lots of interest from both academia and industry. Several methods have been used for producing nanofibers, including electrospinning, melt or solution blowing, phase separation, self-assembly, and template synthesis. However, electrospinning is the most versatile technique to produce nanofibers due to the unique capabilities used to produce nanofibers from different materials (eg, polymers, ceramics, and metals) with different morphologies, patterns, and functionalities. It is interesting that the history of the electrospinning process goes back to the observation of water behavior under the influence of electrostatics in 1700s [5]. Lamor [6] also used electrodynamics to explain the excitation of dielectric liquid under the influence of an electric charge. Eventually, Cooley [7] and Morton [8] invented electrospinning to produce fibers in 1902. Based on a keyword [electrospinning, electrospun, nanofiber] search included in articles using SciFinder Scholar on Oct. 22, 2015, there are 64,685 published articles, of which 50,405 articles are published in the English language. During 2010–15, 35,561 articles (70%) were published that clearly explain the accelerated rate of research in the field of electrospinning/nanofibers in the last few years. The keyword search using the Web of Science (ISI) also indicated this (see Table 1.1).

Table 1.1

Keyword search in title using Web of Science (Nov. 23, 2015)

Keyword in title	Total no. of articles	No. and (%) of articles published in 2010–15	English language	No. and (%) of publications from the United States	No. and (%) of publications from China	No. and (%) of publications from South Korea
Electrospinning	4407	2924 (66%)	2844	353 (12.4%)	1319 (46.3%)	273 (9.6%)
Electrospinnning or electrospun or nanofiber	14,641	10,396 (70%)	10,219	2095 (20.5%)	3606 (35.2%)	1089 (10.6%)

This book is the result of an enormous amount of work by the authors of each chapter to collect and review the progress in different aspects of nanofiber technologies and applications in order to provide the readers a flavor of recent developments made in the field of electrospinning. The topics discussed in each chapter are as follows.

1.1 Part 1: The electrospinning process

1.1.1 Chapter 2: Melt-electrospinning of nanofibers

This chapter summarizes the melt-electrospinning technique for producing nanofibers from thermoplastic polymers, including their characterization techniques and properties, and highlights various applications of nanofibers in bioengineering, sensing, and other areas.

1.1.2 Chapter 3: Coaxial electrospinning of nanofibers

This chapter explores the principles and mechanism of modified electrospinning in the form of coaxial electrospinning, involving an arrangement of multiple concentric spinnerets meant to co-spin compound nano/micro scale fibers. The coaxial electrospinning acted as precursors for a number of sophisticated applications, such as fabrication of hollow and porous structures, and encapsulation of biological agents for transport to the desired parts in the body. The viability and feasibility of these remarkable nanostructures in drug delivery and tissue engineering, energy generation and storage, and environmental decontamination are analyzed.

1.1.3 Chapter 4: Solution electrospinning of nanofibers

This chapter reviews the electrospinning process, variables that affect the electrospinning, and some examples from recent literature on the electrospinning of natural and synthetic polymers and polymer blends.

1.1.4 Chapter 5: Controlling nanofiber morphology through the electrospinning process

The chapter provides an overview of the relationship between processing parameters and morphology of the electrospun nanofibers. These parameters are categorized into three groups: solution properties, process parameters, and ambient conditions. To achieve nanofibers of controlled structures and desirable functions, these parameters should be adjusted properly, and understanding them is very important to understanding the transformation of polymer solutions into nanofibers.

1.1.5 Chapter 6: Improving fiber alignment during electrospinning

A great deal of effort has been made in electrospinning to generate aligned electrospun (ES) fibers and assemblies with controlled fiber directionality. This chapter reviews the current trends in electrospinning nanofibrous membranes with a focus on improving the fiber orientation with discussion of relevant mechanisms involved in the spinning process and overcoming challenges in aligning ultrafine fibers for practical applications.

1.1.6 Chapter 7: Geometrical characterization of electrospun nanofibers

In order to characterize and achieve the desired properties, characterization of geometry and configuration of electrospun nanofibers becomes an important subject during manufacturing and in the final application. This chapter discusses various physical, imaging, and modeling methods of geometrical characterizations of electrospun nanofibers. In addition to importance, the challenges and limitation of geometrical factors and characterization methods have been described. It is expected that soft computing and improved imaging accuracy can be used for improving modeling and characterization of nanofiber geometry.

1.2 Part II: Structure and property characterization, testing, and modeling of electrospun nanofibers

1.2.1 Chapter 8: Chemical characterization of electrospun nanofibers

Chemical characterization of electrospun nanofibers is an important factor in understanding the relationship between structure and properties of nanofibrous materials. This chapter reviews several chemical characterization methods, such as nuclear magnetic resonance, gel permeation chromatography, elemental analysis, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy.

1.2.2 Chapter 9: Physical characterization of electrospun nanofibers

The electrospinning process can use various starting materials, and there are diverse electrospinning processes that can provide particular properties. In this chapter we classify electrospun nanofibers into four categories: electrospun polymer nanofibers, electrospun metal nanofibers, electrospun carbon nanofibers, and electrospun composite nanofibers. Physical characterizations methods such as SEM, TEM, AFM, BET, and conductivity for each category are systematically introduced and illustrated with specific examples.

1.2.3 Chapter 10: Structure–property relationship of electrospun fibers

This chapter discusses the importance of structure of electrospun fibers such as molecular orientation and crystallinity, among others that affect the morphology and microstructure of electrospun nanofibers and change in properties. The objective of this chapter is to provide the readers a flavor of recent developments made in the field of electrospinning to help understand the structure–property relationship of these nanofibers and to appreciate noteworthy advances made in this field in recent times. Understanding crystallization behav...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributors
• Woodhead Publishing Series in Textiles
• 1: Introduction
• Section One: The electrospinning process
• Section Two: Structure and property characterization testing and modeling of electrospun nanofibers
• Section Three: Electrospinning for particular fiber types and applications
• Index