Electrospun nanofiber matrices

Fig. 4 (a) Photograph of the overall 3D woodpile structure with dimensions of 9 x 9 x 3.5 mm. (b) Hybrid basic unit layer composed of microfibers and the electrospun nanofiber matrix, (c, d) Magnified images of (b) (Adapted from [64])... 

Hong Y, Li D, Zheng J, Zou G (2006) In situ growth of ZnO nanocrystals from solid electrospun nanofiber matrixes. Langmuir 22 7331-7334... 

P(3HB-co-4HB) copolymers are known to be biocompatible material. The biocompatible nature of these copolymers allows it to be utilized for various medical applications. These PHA polymers have been tested in tissue engineering applications as surgical sutures, bone plates, implants, gauzes, osteosynthetic materials, and also as matrix material assisting slow release of drugs and hormones (Zinn et al. 2001 Williams and Martin 2002 Sudesh 2004 Chen and Wu 2005 Freier 2006). Recently, electrospun nanofibers of P(3HB-co-4HB) have been evaluated as scaffolds in vivo and in vitro (Ying et al. 2008). 

The reinforcing effects of nanofibers in an epoxy matrix and in a rubber matrix using electrospun nanofibers of polybenzimidazole (PBl) was observed. The average diameter of the electrospun fibers was around 300 nm. The nanofibers toughened the brittle epoxy resin. The fracture toughness and modulus of the nanofiber (15 wt.%)-reinforced epoxy composite were both higher than for an epoxy composite made with PBl fibrils (17 wt.%], which were whisker-like particles. 

In the PANI.TSA/PLA blended electrospun nanofibers no phase segregation of PANI in a PLA matrix was observed, while phase segregation was observed in cast films with the same composition. Due to rapid solvent evaporation in the electrospinning process, no crystalline structures in fiber mats were formed compared to cast films. Highly homogeneous electroactive fibers can be useful in the construction of electronic devices and sensors. Similar behavior was observed in the PVDF-TrFE/PANI-PSSA electrospun nanofibers. 

Electrospun nanofibers can be compacted or combined with other polymers to prepare polymer-polymer composites. If there is no or only poor adhesion between the fibers and the matrix, a beaded structure as shown in Fig. 7.5 or other local thickenings along the fibers can prevent pulling-out effects and, therefore, increase the strength of the composites. Nanofibers are illustrated in more detail in Section 9.4. 

Xu, C. Y., R. Inai, M. Kotaki, and S. Ramakrishna (2004b). Electrospun nanofiber fabrication as synthetic extracellular matrix and its potential for vascular tissue engineering. Tissue Engineering 10(7-8) 1160-1168. 

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