Polyurethane nanofiber mats

Unnithan, A.R. Barakat, N.A.M. Pichiah, RB.T. Gnanasekaran, G. Nirmala, R. Cha, Y.S. Jung, C.H. El-Newehy, M. Kim, H.Y. Wound-dressing materials with antibacterial activity from electrospun polyurethane-dextran nanofiber mats containing ciprofloxacin HCl. Carbohydr. Polym. 2012, 90 (4), 1786-1793. 

Jeong, E. H., J. Yang, J. H. Youk, Preparation of polyurethane cationomer nanofiber mats for use in antimicrobial nanofilter applications. Materials Letters, 2007, 61(18), 3991-3994. 

TABLE 5.2 Porosimetric and modulus data illustrating the effect of changing solvent composition on electrospun segmented polyurethane nanofiber mat characteristics... 

TABLE 5.4 Tensile properties of thermoplastic polyurethane nanofiber mats... 

MMT is a reinforcing filler in polymers such as poly(urea urethane) (Ge et al. 2000) as evidenced by the very significant increase in mechanical properties of the composite nanofibers. Unfilled polymer nanofiber mats of polyurethane (PU) (M — 150,000 g/mol) were electrospun from llwt% solution in DMAc/THF (7 3wt/wt) into nanofibers with 150nm to 410nm. The tensile properties of these mats are shown in Table 6.4, where the last digit in the nanofiber designation is the weight fraction of MMT in the polymer. Based on the WAXD patterns for the composite nanofibers, MMT appeared to be well dispersed, exfoliated, and oriented in the axial direction of the samples. 

Zhou et al. (2006) studied the mechanical properties of electrospun mats of PLLA/MMT with 1 - 5 wt% of the nanoclay in composite fibers. The nanoclay and PLLA were intimately mixed in a high-speed mixer and the blend electrospun from 10-25 wt% chloroform solution to obtain the composite nanofiber mats. The yield stress (MPa) of the composite nanofiber mats improved more than threefold with the incorporation of 3wt% of the clay, while the modulus doubled. This is consistent with the results in Table 6.4 for polyurethane nanofibers (Hong, J. H., et al. 2005). 

The way in which Cherian et al. fabricated the nanobiocomposites was by stacking the cellulose nanofiber mats between polyurethane films and pressing by compression molding. With the addition of 5 wt% cellulose nanofbers into polyurethane the strength and stiffness increased by nearly 300% and 2600%, respectively. The developed composites were utilized to fabricate various versatile medical implants. Cellulose poly-urethanes-based materials are sufficiently durable and blood compatible for potential use in a prosthetic heart valves and effectively showed less mineralization than glutar-aldehyde-fixed bovine pericardial tissue [231]. 

Another modified spinneret was designed with multiple single jets in order to enhance nanofibers spinning rate of PEO (Theron et al. 2005) or to prepare nanofibrous mats composed of two different and immiscible polymers such as PVA and cellulose acetate. A multiple jet composed of four tips was used in order to blend PVA and cellulose acetate nanofibers in different ratios (Pham et al. 2006). In another study, a collector moving transversely was used in front of a multiple jet composed of two tips in order to produce a mixture of electrospun PEO and polyurethane (PU) nanofibers and a uniform distribution of this mixture was achieved due to the motion of the collector (Kidoaki et al. 2005). 

At moderate strains the modulus of an isotropic fiber mat of pellathene (polyurethane) nanofibers electrospun from 7% DMF was higher than that of the bulk polymer (Pedicini and Farris 2003). Similar data were reported for PAN nanofibers (Fennessey et al. 2006). 

Hassan MS, Amna T, Sheikh FA, Al-Deyab SS, Choi KE, Hwang IH, KMl MS (2013) Bimetallic Zn/Ag doped polyurethane spider net composite nanofibers a novel multipurpose electrospun mat. Ceramics Int 39 2503-2510... 

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