**1. Introduction**

In general, nanocomposites are defined as the combination of multiphase materials in which at least one of the constituents has one dimension in the nanometer range [1]– [3]. The nanoscale constituent could be one dimensional likenanofibres and nanowires, two-dimensional like nanoclay or three-dimensional like spherical particles in nanoscale range. Nanofibers rein‐ forced polymermultifunctionalitycan be attributed to the combination of the constituent materials. Desired properties of nanofibers reinforced polymercan be obtained by the selection of the constituent materials and the size of the nanofibress based on the required application. Current research has focused in the areas of manufacturing techniques and material combi‐ nation for the fabrication of the nanostructured reinforced polymers [4], [5].

Nanofibers reinforced polymer are progressing with the use of a combination of atomic scale characterization and detailed modeling. In the early 1990s, Toyota Central Research Labora‐ tories in Japan reported working on a Nylon-6 nanocomposite [6], in which a small amount of nano filler resulted in a considerable improvement of thermal and mechanical properties. The properties of nanofibers reinforced polymer materials depend on their morphology and interfacial characteristics as well as on the properties of their individual parents (nanofillers and polymer, in this case).

Dramatic changes in physical properties will be the result of the transition from microparticles to nanoparticles. Nanoscale materials have a large surface area for a given volume [7]. A nanostructured material can have substantially different properties from a larger-dimensional material of the same composition because many important chemical and physical interactions are governed by surfaces and surface properties. In the case of nanoparticles and nanofibers, the surface area per unit volume is inversely proportional to the material's diameter. So, the smaller the diameter, the greater is the surface area per unit volume [7]. Figure 1 shows

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common particle geometries and their respective surface area-to-volume ratios. For the nanofiber and layered material, the surface area to volume ratio is dominated by the first term in the equation, especially for nanomaterials. The second term (2/l and 4/l ) has a very small influence and is often omitted compared to the first term. Therefore, a changefrom the micrometer to nanometer in particle diameter, layer thickness, or fibrous material diameter range, will affect the surface area to volume ratio by three orders of magnitude [8].

when the silicate layers are completely and uniformly dispersed in a continuous polymer matrix. In any case, the physical properties of the resultant nanofibers reinforced polymer will be significantly different, as discussed in the following sections. Similarly, in fibrous or particle-reinforced polymer nanofibers reinforced polymer (PNCs), dispersion of the nano‐ particle and adhesion at the particle–matrix interface play crucial roles in determining the mechanical properties of the nanofibers reinforced polymer. The nanomaterial will not offer improved mechanical properties without proper dispersion. A poorly dispersed nanomaterial may degrade the mechanical properties of the produced reinforced polymers [12]. Addition‐ ally, optimizing the interfacial bond between the nanostructures and the matrix, one can tailor the properties of the overall nanofibers reinforced polymer in a similar manner to what is done in macrocomposites. As an example, good adhesion at the interface will improve properties such as interlaminar shear strength, fatigue, delamination resistance,and corrosion resistance. Finally, it is important to recognize that snanofibers reinforced polymer researches are extremely broad,encompassing areas such as communications, electronics and computing, data storage, aerospace and sporting materials, health and medicine, transportation, energy, environmental, and many other applications. The focus of this chapter is to highlight the state of knowledge in processing, fabrication, characterization, properties, and potential applica‐

Nanofibers Reinforced Polymer Composite Microstructures

http://dx.doi.org/10.5772/57101

167

The advancement in the technology of MicroElectroMechanical Systems (MEMS) has demand for the fabrication of 3D micro/nanostructures and devices. The excitement surrounding the nanoscale science and technology gives us unique opportunities to develop and examine revolutionary processes and materials. Nanofibers reinforced polymer embedded with 2D and 3D micro/nano materials find many applications in the field of medicine, tissue engineering, drug delivery, antibacterial implants or catheters, modification of textiles, and modification of polymers. Many optical, electrical and magnetic applications, have opened up new areas of research for manufacturing nanofibers reinforced polymer with engineered nanoparticles

Researchers have been working on different micro/nano manufacturing techniques. LIGA (German acronym for Lithographie, Galvanoformung, Abformung) [7], [8], Photolithography (6), Electrochemical Fabrication (EFAB) [9], localize electrochemical deposition [10] and laser sintering [13] are some of the techniques used for micro/nano fabrication. Some of these techniques have been used for the fabrication of nanofibers reinforced polymer by dispersing

The LIGA technique was invented approximately 20 years ago. It is a powerful method that facilitates the high volume production of nanofibers reinforced polymer components for many fields of applications [14]. Researchers presented designs, fabrication and experimental results of high power electrostatic microactuators, using LIGA process. This process is capable of producing high aspect ratio microstructures of nanofibers reinforced polymer, as shown in

tions of the nanofibrous reinforced polymer microstructures.

**2. Fabrication techniques**

nanofibers in polymer resins.

materials.

Figure 3 [15].

**Figure 1.** Common particle reinforcements/geometries and their respective surface areatovolume ratios. [8].

Typical nanomaterials currently under investigation include nanoparticles, nanotubes, nanofibers, fullerenes, and nanowires. In general, these materials are broadly classified by their geometries [9]: particle, layered, and fibrous nanomaterials [8], [9]. Carbon black, silica nanoparticle, polyhedral oligomericsislesquioxanes, can be classified as nanoparticle reinforc‐ ing agents, while nanofibers and carbon nanotubes are examples of fibrous materials [9]. When the filler has a nanometer thickness and a high aspect ratio (30–1000) plate-like structure, it is classified as a layered nanomaterial such as an organosilicate [10].

In general, the high aspect ratio of nanomaterials provides the necessary reinforcement properties. The properties of reinforced polymers are greatly influenced by the size of its nanomaterial and the quality of the interfacing between the matrix material and the filler material. Significant differences in composite properties may be obtained depending on the nature of the filler material used whether its layered silicate or nanofiber, cation exchange capacity, or polymer matrix and the method of preparation [11]. As an example, when the polymer is unable to intercalate (or penetrate) between the silicate sheets, a phase-separated composite is obtained, and the properties stay in the same range as those for traditional microcomposites [10]. In an intercalated structure, where a single extended polymer chain can penetrate between the silicate layers, a well-ordered multilayer morphology results with alternating polymeric and inorganic layers. An exfoliated or delaminated structure is obtained when the silicate layers are completely and uniformly dispersed in a continuous polymer matrix. In any case, the physical properties of the resultant nanofibers reinforced polymer will be significantly different, as discussed in the following sections. Similarly, in fibrous or particle-reinforced polymer nanofibers reinforced polymer (PNCs), dispersion of the nano‐ particle and adhesion at the particle–matrix interface play crucial roles in determining the mechanical properties of the nanofibers reinforced polymer. The nanomaterial will not offer improved mechanical properties without proper dispersion. A poorly dispersed nanomaterial may degrade the mechanical properties of the produced reinforced polymers [12]. Addition‐ ally, optimizing the interfacial bond between the nanostructures and the matrix, one can tailor the properties of the overall nanofibers reinforced polymer in a similar manner to what is done in macrocomposites. As an example, good adhesion at the interface will improve properties such as interlaminar shear strength, fatigue, delamination resistance,and corrosion resistance. Finally, it is important to recognize that snanofibers reinforced polymer researches are extremely broad,encompassing areas such as communications, electronics and computing, data storage, aerospace and sporting materials, health and medicine, transportation, energy, environmental, and many other applications. The focus of this chapter is to highlight the state of knowledge in processing, fabrication, characterization, properties, and potential applica‐ tions of the nanofibrous reinforced polymer microstructures.
