**2. Importance of nano fibers to the present day perspective**

Today's world is facing many challenges to run things in a smooth manner. Many man made things outburst as a threat to human life. In order to overcome such challenges researchers looked into fabrication of nano fibers that have substantial benefits in various fields. For example, globalization and modernization brought many hazardous things like plastic into day to day life of common man. Plastic is one of major pollutant that cannot decompose easily into Earth. Likewise, many materials are bringing challenges for better livelihood.

Nano fibers are alternative resources for many materials due to their excellent properties. These materials are emerging as substituents for original materials due to their low cost, low density, high porosity, high energy. These unique features enable nano fibers for novel applications.

Nano science and nano technology have been vital applicative for scientific world since antiquity. Impact of nano on the present world empowers and drives one to develop new aspects in many areas. Researchers thrive to dwell the inherence of nano to synthesize from different materials. Fibrous materials have been used as best replacement for many non-renewable sources with less cost. They have been used in day to day applications like mobiles, solar cells, batteries, filtration membranes etc. In many cases these materials are taken from end users or wastes. For example, cellulose nano whiskers can be prepared from coconut fiber [1]. Sea algae is also being used to prepare nano fibers with numerous applications [2]. Different methods like electron spinning, self-assembly, template synthesis, thermal induction and phase separation etc. are used to make nano fibers [3]. These methods include chemical and mechanical techniques. Nano fibers extracted from natural and synthetic polymers are authentic besties to nature.

Flexibility, high tensile strength is the major advantage of these fibers with enhanced properties. Knowing about the various types of nano fibers, their synthesis, properties with basic as well as commercial applications at one glance is the main emphasis of this chapter.

#### **3. Generation of nano fibers**

Nano fibers are generated from diverse materials show differences in physical properties as well as application potentials. Natural polymers, synthetic polymers, carbon based materials, metals, ceramics, semiconducting materials and composite materials are used for the preparation of nano fibers [4]. **Figure 1** shows the materials used to synthesize nano fibers. Each of these materials have specific importance and applications.

#### **4. Natural and synthetic polymers**

Dominance of renewable sources in the preparation of nano fibrous materials has been increased drastically in this decade due to their environment friendly properties. These renewable sources include polymers were paid much attention from their biocompatible, bio degradable and bio active nature. Starting from

**3**

*New Perspective of Nano Fibers: Synthesis and Applications*

physical properties proliferation, adhesion, migration, cell adhesion are most

Collagen, Cellulose, silk fibroin, keratin, gelatin and polysaccharides (chitosan, alginate) are the natural polymers and can be used to synthesize nano fibers using

Collagen is an excellent protein in the extra cellular matrix found in connective tissues of body. The structure of collagen is helical with amino acids bound together which is elongated fibril also known as collagen helix. Nano fibrous materials generated from this regenerative biopolymer are used in reconstruction

Nano structured cellulose fibers are commonly referred as cellulose nano fibers. Cellulose nano crystal, cellulose nano fibers, nano fibrillated cellulose and bacterial nano cellulose are the nano fibered cellulose with different physical, chemical and

These fibrils are with high aspect ratio that is 5–20 nm width and some micrometers length. Many plant based products, biological products, sea products are the basis of cellulose. As an example the nano fibers from cellulose develops microfiber

Silk fibroin is produced from silkworms and spiders. It has excellent mechanical properties with biological compatibility, morphological flexibility used to produce nano fibers mostly using electrospun technique [11]. The stability of fibers from silk is obtained from chemical treatments such as methanol, ethanol, propanol and water vapor. If viscoelasticity of silk fibroins is increased with blending them with polymers an improvement in mechanical properties were observed while biological

evitable properties the makes one to rely to produce nano fibers.

various techniques [5–7].

*Synthesis of nano fibers from various materials.*

**4.1 Collagen**

**Figure 1.**

of tissues [8].

**4.2 Cellulose**

biological properties [9].

3D printing network [10].

properties remain [12].

**4.3 Silk fibroins**

*DOI: http://dx.doi.org/10.5772/intechopen.97460*

*New Perspective of Nano Fibers: Synthesis and Applications DOI: http://dx.doi.org/10.5772/intechopen.97460*

**Figure 1.** *Synthesis of nano fibers from various materials.*

physical properties proliferation, adhesion, migration, cell adhesion are most evitable properties the makes one to rely to produce nano fibers.

Collagen, Cellulose, silk fibroin, keratin, gelatin and polysaccharides (chitosan, alginate) are the natural polymers and can be used to synthesize nano fibers using various techniques [5–7].

### **4.1 Collagen**

*Nanofibers - Synthesis, Properties and Applications*

matrices that have large beneficiations to mankind.

materials are bringing challenges for better livelihood.

and synthetic polymers are authentic besties to nature.

main emphasis of this chapter.

**3. Generation of nano fibers**

**4. Natural and synthetic polymers**

and applications.

enable nano fibers for novel applications.

**2. Importance of nano fibers to the present day perspective**

Unambiguous properties of nano fibers intend to modify or reinforce polymer

Today's world is facing many challenges to run things in a smooth manner. Many

Nano fibers are alternative resources for many materials due to their excellent properties. These materials are emerging as substituents for original materials due to their low cost, low density, high porosity, high energy. These unique features

Nano science and nano technology have been vital applicative for scientific world since antiquity. Impact of nano on the present world empowers and drives one to develop new aspects in many areas. Researchers thrive to dwell the inherence of nano to synthesize from different materials. Fibrous materials have been used as best replacement for many non-renewable sources with less cost. They have been used in day to day applications like mobiles, solar cells, batteries, filtration membranes etc. In many cases these materials are taken from end users or wastes. For example, cellulose nano whiskers can be prepared from coconut fiber [1]. Sea algae is also being used to prepare nano fibers with numerous applications [2]. Different methods like electron spinning, self-assembly, template synthesis, thermal induction and phase separation etc. are used to make nano fibers [3]. These methods include chemical and mechanical techniques. Nano fibers extracted from natural

Flexibility, high tensile strength is the major advantage of these fibers with enhanced properties. Knowing about the various types of nano fibers, their synthesis, properties with basic as well as commercial applications at one glance is the

Nano fibers are generated from diverse materials show differences in physical properties as well as application potentials. Natural polymers, synthetic polymers, carbon based materials, metals, ceramics, semiconducting materials and composite materials are used for the preparation of nano fibers [4]. **Figure 1** shows the materials used to synthesize nano fibers. Each of these materials have specific importance

Dominance of renewable sources in the preparation of nano fibrous materials has been increased drastically in this decade due to their environment friendly properties. These renewable sources include polymers were paid much attention from their biocompatible, bio degradable and bio active nature. Starting from

man made things outburst as a threat to human life. In order to overcome such challenges researchers looked into fabrication of nano fibers that have substantial benefits in various fields. For example, globalization and modernization brought many hazardous things like plastic into day to day life of common man. Plastic is one of major pollutant that cannot decompose easily into Earth. Likewise, many

**2**

Collagen is an excellent protein in the extra cellular matrix found in connective tissues of body. The structure of collagen is helical with amino acids bound together which is elongated fibril also known as collagen helix. Nano fibrous materials generated from this regenerative biopolymer are used in reconstruction of tissues [8].

## **4.2 Cellulose**

Nano structured cellulose fibers are commonly referred as cellulose nano fibers. Cellulose nano crystal, cellulose nano fibers, nano fibrillated cellulose and bacterial nano cellulose are the nano fibered cellulose with different physical, chemical and biological properties [9].

These fibrils are with high aspect ratio that is 5–20 nm width and some micrometers length. Many plant based products, biological products, sea products are the basis of cellulose. As an example the nano fibers from cellulose develops microfiber 3D printing network [10].

### **4.3 Silk fibroins**

Silk fibroin is produced from silkworms and spiders. It has excellent mechanical properties with biological compatibility, morphological flexibility used to produce nano fibers mostly using electrospun technique [11]. The stability of fibers from silk is obtained from chemical treatments such as methanol, ethanol, propanol and water vapor. If viscoelasticity of silk fibroins is increased with blending them with polymers an improvement in mechanical properties were observed while biological properties remain [12].

#### **4.4 Keratin**

One of the most abundant non-food protein is Keratin. Components of hair, feathers, nails, horns of mammals and birds are the many sources of keratin [13]. Despite of having so many good characteristics the keratin wastes are being pollutants. If the wastes are brunt they would release toxins due to Sulphur content. Instead of burning them and make as pollutants one can produce nano fibrous out of keratin by electrospinning technique that finds application in tissue engineering and many filtration devices [14].

For example, human hair mixed with polycaprolactone (PCL) in proper proportions to produce nanofibrous membranes that have excellent applications to develop composite materials and also can be used in various biomedical applications [15].

#### **4.5 Gelatin**

Gelatin is a natural polymer which is renewable acquired by fractional hydrolysis of collagen. It is most favorable bioengineering material due to its low cost, high biocompatibility and biodegradability [16]. Electrospun gelatin nano fibers face a difficult in water solubility with poor mechanical strength. To overcome this problem crosslinking technique like drying, heating and UV light exposure with some chemical treatments are induced [17].

#### **4.6 Polysaccharides**

Chitosan is one of polysaccharide obtained from deacetylation of chitin polymer. It is a natural source found in exoskeleton of insects, crustaceans and fungi. With excellence in properties like biodegradability, biocompatibility, nontoxicity chitosan suits for biomedical applications. Large variety of fungi, yeasts, bacteria can be inhibited by chitosan and through electrospinning technique nano fibers are prepared [18]. These specifications made chitosan ample with opportunities in biomedical and other fields of industry.

## **5. Synthetic polymers**

Polyvinyl alcohol Polycaprolactone (PCL), polyurethane (PU), poly(lacticco-glycolicacid) (PLGA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and poly(ethylene-co-vinyl acetate) (PEVA) are the synthesized polymers that can be used to prepare nano fibers with different techniques [19–21]. Poly Lactic acid (PLA), Poly glycolic acid (PGA) and their copolymer (PLGA) are biodegradable found applications in medical field [22].

These all are water soluble polymers with good mechanical properties. Some of these synthesized polymers are strong enough with good antimicrobial and antifungal activities. Combining with natural polymers these synthesized new scaffolds were prepared for various applications [23].

#### **6. Semiconducting materials**

In the present day scenario semiconducting materials looks forward to develop many new technologies that relates to environment and society. Reduction of a material to its nano size exhibit numerous novel properties with a wide range of applications include energy materials, optoelectronic devices, biomedical imaging

**5**

*New Perspective of Nano Fibers: Synthesis and Applications*

etc. [23]. The size dependent tuneable band gaps of semiconductors exhibit excellent properties and are used to generate nano fibers. Many fibrous materials that possess semiconducting properties can be prepared from versatile techniques. Three different sources acetylene, ethanol and cotton were used to prepare semiconductor carbon nano fibers. Many electronic functionalities like light emitting diodes, photonic compounds, field effect transistors are used to fabricate nano fibers [24].

Metals and composite materials have explicit optical, physical and electrical properties. These special features avail the materials amalgamate with nano fibrils to develop new fibrous materials [25]. The newly developed materials exhibit stability, flexibility, bio compatibility, selectivity and improved sensitivity.

Formation of stable organic as well as inorganic molecules is possible from high flexible nature of carbon. Notable mechanical, thermal, electrical properties versatile carbon materials and intrudes the formation of carbon nano fibers [26].

Nano fibers from these materials can be obtained from various physical, chemical

Synthesis of nano fibers include various chemical and mechanical and optical methods. From their early preparation till to date so many techniques keep on coming to generate fibrous materials in nano size. Nano fibers are generated from various technologies electrospinning, self-assembly, template based synthesis, polymerization, sonochemical synthesis [27]. **Figure 2** shows the synthesis mechanism of nano fibers from various techniques. Along with these methods freeze drying or lyophilization is another technique used to produce nano fibers from cellulose materials. There are few ongoing and upcoming new technologies to synthesize nano fibers. Few of them are electro-hydrodynamic writing, plasma induced synthesis, solution blow spinning, centrifugal jet spinning, CO2 laser

Of all the availability techniques electrospinning is adaptable mechanism for the production of nano fibers [28–31]. In this technique simple experimental arrangement is used to prepare nano fibers. An electric source, a syringe with nozzle, a counter electrode, target and a pump is the experimental setup to generate fibers at nano scale as shown in **Figure 3**. The principle of this technique is the electrostatic repulsion force produced in a high electrical field. The ejected solution forms into Tylor cone due to the potential difference. The solvent in the solution evaporates that leads to the formation of nano fibers and collected at collector. New improvisation in conventional electrospinning technique is done to generate nano fibers with enhanced properties. There are several types of electrospinning methods that includes multi axial, Co-axial, tri axial electrospinning, bi-component, mutlineedle electrospinning, needle less- bubble, two-layer fluid, splashing electrospinning are the techniques implementing to improve the nano

Majority of fibrous materials from natural and synthetic polymers are generated

These CNF's also acts as essences for composite materials.

or mechanical techniques explained in detail further in this chapter.

*DOI: http://dx.doi.org/10.5772/intechopen.97460*

**6.1 Metals and composite materials**

**6.2 Carbon based materials**

**7. Synthesis Mechanism**

supersonic drawing.

fiber productivity [32].

from electrospinning and its related techniques.

*New Perspective of Nano Fibers: Synthesis and Applications DOI: http://dx.doi.org/10.5772/intechopen.97460*

etc. [23]. The size dependent tuneable band gaps of semiconductors exhibit excellent properties and are used to generate nano fibers. Many fibrous materials that possess semiconducting properties can be prepared from versatile techniques. Three different sources acetylene, ethanol and cotton were used to prepare semiconductor carbon nano fibers. Many electronic functionalities like light emitting diodes, photonic compounds, field effect transistors are used to fabricate nano fibers [24].

#### **6.1 Metals and composite materials**

Metals and composite materials have explicit optical, physical and electrical properties. These special features avail the materials amalgamate with nano fibrils to develop new fibrous materials [25]. The newly developed materials exhibit stability, flexibility, bio compatibility, selectivity and improved sensitivity.

#### **6.2 Carbon based materials**

*Nanofibers - Synthesis, Properties and Applications*

and many filtration devices [14].

some chemical treatments are induced [17].

biomedical and other fields of industry.

One of the most abundant non-food protein is Keratin. Components of hair, feathers, nails, horns of mammals and birds are the many sources of keratin [13]. Despite of having so many good characteristics the keratin wastes are being pollutants. If the wastes are brunt they would release toxins due to Sulphur content. Instead of burning them and make as pollutants one can produce nano fibrous out of keratin by electrospinning technique that finds application in tissue engineering

For example, human hair mixed with polycaprolactone (PCL) in proper proportions to produce nanofibrous membranes that have excellent applications to develop composite materials and also can be used in various biomedical applications [15].

Gelatin is a natural polymer which is renewable acquired by fractional hydrolysis of collagen. It is most favorable bioengineering material due to its low cost, high biocompatibility and biodegradability [16]. Electrospun gelatin nano fibers face a difficult in water solubility with poor mechanical strength. To overcome this problem crosslinking technique like drying, heating and UV light exposure with

Chitosan is one of polysaccharide obtained from deacetylation of chitin polymer. It is a natural source found in exoskeleton of insects, crustaceans and fungi. With excellence in properties like biodegradability, biocompatibility, nontoxicity chitosan suits for biomedical applications. Large variety of fungi, yeasts, bacteria can be inhibited by chitosan and through electrospinning technique nano fibers are prepared [18]. These specifications made chitosan ample with opportunities in

Polyvinyl alcohol Polycaprolactone (PCL), polyurethane (PU), poly(lactic-

These all are water soluble polymers with good mechanical properties. Some of these synthesized polymers are strong enough with good antimicrobial and antifungal activities. Combining with natural polymers these synthesized new scaffolds

In the present day scenario semiconducting materials looks forward to develop many new technologies that relates to environment and society. Reduction of a material to its nano size exhibit numerous novel properties with a wide range of applications include energy materials, optoelectronic devices, biomedical imaging

co-glycolicacid) (PLGA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and poly(ethylene-co-vinyl acetate) (PEVA) are the synthesized polymers that can be used to prepare nano fibers with different techniques [19–21]. Poly Lactic acid (PLA), Poly glycolic acid (PGA) and their copolymer (PLGA) are

biodegradable found applications in medical field [22].

were prepared for various applications [23].

**6. Semiconducting materials**

**4.4 Keratin**

**4.5 Gelatin**

**4.6 Polysaccharides**

**5. Synthetic polymers**

**4**

Formation of stable organic as well as inorganic molecules is possible from high flexible nature of carbon. Notable mechanical, thermal, electrical properties versatile carbon materials and intrudes the formation of carbon nano fibers [26]. These CNF's also acts as essences for composite materials.

Nano fibers from these materials can be obtained from various physical, chemical or mechanical techniques explained in detail further in this chapter.

## **7. Synthesis Mechanism**

Synthesis of nano fibers include various chemical and mechanical and optical methods. From their early preparation till to date so many techniques keep on coming to generate fibrous materials in nano size. Nano fibers are generated from various technologies electrospinning, self-assembly, template based synthesis, polymerization, sonochemical synthesis [27]. **Figure 2** shows the synthesis mechanism of nano fibers from various techniques. Along with these methods freeze drying or lyophilization is another technique used to produce nano fibers from cellulose materials. There are few ongoing and upcoming new technologies to synthesize nano fibers. Few of them are electro-hydrodynamic writing, plasma induced synthesis, solution blow spinning, centrifugal jet spinning, CO2 laser supersonic drawing.

Of all the availability techniques electrospinning is adaptable mechanism for the production of nano fibers [28–31]. In this technique simple experimental arrangement is used to prepare nano fibers. An electric source, a syringe with nozzle, a counter electrode, target and a pump is the experimental setup to generate fibers at nano scale as shown in **Figure 3**. The principle of this technique is the electrostatic repulsion force produced in a high electrical field. The ejected solution forms into Tylor cone due to the potential difference. The solvent in the solution evaporates that leads to the formation of nano fibers and collected at collector. New improvisation in conventional electrospinning technique is done to generate nano fibers with enhanced properties. There are several types of electrospinning methods that includes multi axial, Co-axial, tri axial electrospinning, bi-component, mutlineedle electrospinning, needle less- bubble, two-layer fluid, splashing electrospinning are the techniques implementing to improve the nano fiber productivity [32].

Majority of fibrous materials from natural and synthetic polymers are generated from electrospinning and its related techniques.

**Figure 2.**

*Representation of Conventional and Modern Methods for synthesis of nano fibers.*

**Figure 3.**

*Representation of nanofiber production with basic electrospinning method [32].*
