Crosslinked nanofibers

Crosslinking renders the nanofibers insoluble in all solvents. When a crosslinked fiber mat is placed in a good solvent, it absorbs the solvent and swells rather than dissolving in it. In filters, sensors, and biological applications such insolubility can be desirable. 

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Interconnected fibrous membranes generated by electrospinning an aqueous mixture of polymers. The crosslinked nanofibers shown to act like anionic hydrogels. 

Fig. 1 Nanofiber modification strategies. In step 1, many polymer and solution properties will affect the size, stability, and reactivity of nanofihers in the final mat, including multipolymer blending strategies, incorporation of soluble factors/drugs/spheres, and/or loading concentrations. In step 2, during spinning, the ambient conditions and voltage applied must be tailored for each polymer source and can be dictated by the nature of the collector or the number of jets employed simultaneously. In step 5, the as-spun mat can be modified by various crosslinking techniques to stabilize the polymers or, in the case of soluble or carrier polymers, these can be leached out by subsequent liquid washes...

Vondran JL, Sun W, Schauer CL (2008) Crosslinked, electrospun chitosan-poly(ethylene oxide) nanofiber mats. J Appl Polym Sci 109(2) 968-975... 

In a PHIC chain, the backbone, covered by a corona of hexyl groups, consists of a Unear sequence of imide units. Their counterparts in the PS-PCEMA nanofiber are the cross-linked PCEMA cylindrical core and the PS chains as the corona. Other than the size difference, the PHIC molecule and the PS-PCEMA nanofiber bear a remarkable structural resemblance. If the PCEMA crosslinking density is high, the PtBA chains in a PS-PCEMA-PtBA nanofiber and the PAA chains in a PS-PCEMA-PAA nanotube become trapped inside the cores even if the solvent is good for both PtBA and PAA. Thus, the triblock copolymer nanofibers and nanotubes can be viewed as giant polymer chains as well [18]. 

Figures 12.1.14-12.1.16 show a variety of shapes which have been observed. These include nanospheres, assemblies of cylindrical aggregates, and nanofibers." Nanospheres were obtained by the gradual removal of solvent by dialysis, fibers were produced by a series of processes involving dissolution, crosslinking, and annealing. Figure 12.1.17 sheds some light on the mechanism of aggregate formation. Two elements are clearly visible from micrographs knots and strands. Based on studies of carbohydrate amphiphiles, it is concluded that knots are formed early in the process by spinodal decomposition. Formation of...

Electrospun conducting polymer nanofibers (diameter ca. 120 nm) also exhibited a desirable electrochromic property [438]. The electrospun conducting polymer nanofibers formed an interconnected network by solid/ swollen-state oxidative crosslinking without significant perturbation of the morphology. Nanofibers showed relatively fast switching times of 2-3 s. 

Cay, A. and Miraftab, M. (2013) Properties of electrospun poly(vinyl alcohol) hydrogel nanofibers crosslinked with 1,2,3,4-butanetetracarboxylic acid. J. 

The authors successfully prepared chemically cross-linked temperature-responsive electrospun nanofibers by thermal curing [llj. As a member of the NIPAAm family, N-hydroxymethylacrylamide (HMAAm) was copolymerized with NIPAAm by free-radical copolymerization because temperature-responsive HMAAm can be cross-linked by self-condensation at high temperatures (above 110°C). As a result of cross-linking, very stable nanofibers in aqueous solution were obtained and manipulated as a bulk material. By extension of the above-mentioned examples, the authors successfully prepared temperature-responsive electrospun nanofibers by photocuring [12]. The temperature-responsive nanofiber mats were prepared using the copolymers NIPAAm and 2-carboxyisopropylacrylamide conjugated to 4-aminobenzophenone, a photoinitiator. The crosslinked temperature-responsive nanofibers were obtained by UV irradiation for 30 min (Fig. 5.4.3). Chemically cross-linked nanofibers were also reported by... 

Vivod S L, Meador M A B, Nguyen B N, Quade D, Randall J (2(X)8) Di-isocyanate crosslinked aerogels with l,6-bis(trimethoxysilyl)hexane incorporated in silica backbone. Polym Preprints 49 521-522 Vivod S L, Meador M A B, Capadona L A, Sullivan R M, Ghosn L J, Clark N, McCorkle L, Quade D J (2(X)8) Carbon nanofiber incorporated silica based aerogels with di-isocyanate cross-linking. Polym Preprints 49 306 307... 

This section studies the effect of the structure and composition of carbon nanofibers obtained by co-catalyst washed and not washed from the metal catalyst on the kinetics and properties of vulcanized ethylene propylene diene rubber. It is shown that the fibers obtained on the co-catalyst accelerate the crosslinking of EPDM, improve the physical and mechanical properties, increase the molecular mobility. The purpose of this research—investigation of the carbon nanofibers influence produced by co-catalysts on the physical and mechanical properties and structure of synthetic EPDM. 

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