Partner: Eyal Zussman

Technion - Israel Institute of Technology (IL)

Ostatnie publikacje
1.Boas M., Gradys A., Vasilyev G., Burman M., Zussman E., Electrospinning polyelectrolyte complexes: pHresponsive fibers, SOFT MATTER, ISSN: 1744-683X, DOI: 10.1039/c4sm02618g, Vol.11, pp.1739-1747, 2015

Streszczenie:

Fibers were electrospun from a solution comprised of oppositely charged polyelectrolytes, in efforts to achieve highly confined macromolecular packaging. A stoichiometric ratio of poly(allylamine hydrochloride) and poly(acrylic acid) solution was mixed in an ethanol–water co-solvent. Differential scanning calorimetry (DSC) analysis of electrospun fibers demonstrated no indication of glass transition, Tg. Infrared spectroscopy (FTIR) analysis of the fibers as a function of temperature, demonstrated an amidation process at lower temperature compared to cast film. Polarized FTIR indicated a preference of the functional groups to be perpendicular to the fiber axis. These results imply formation of mixed phase fibers with enhanced conditions for intermolecular interactions, due to the highly aligned and confined assembly of the macromolecules. The tunable intermolecular interactions between the functional groups of the polyelectrolytes, impact pH-driven, reversible swelling–deswelling of the fibers. The degree of ionization of PAA at pH 5.5 and pH 1.8 varied from 85% to 18%, correspondingly, causing transformation of ionic interactions to hydrogen bonding between the functional groups. The chemical change led to a massive water diffusion of 500% by weight and to a marked increase of 400% in fiber diameter, at a rate of 0.50 μm s−1. These results allow for manipulation and tailoring of key fiber properties for tissue engineering, membranes, and artificial muscle applications.

Słowa kluczowe:

polyelectrolytes, electrospinning, pH responsive fibers

Afiliacje autorów:

Boas M.-Technion - Israel Institute of Technology (IL)
Gradys A.-IPPT PAN
Vasilyev G.-Technion - Israel Institute of Technology (IL)
Burman M.-Technion - Israel Institute of Technology (IL)
Zussman E.-Technion - Israel Institute of Technology (IL)
40p.
2.Alhazov D., Gradys A., Sajkiewicz P., Arinstein A., Zussman E., Thermo-mechanical behavior of electrospun thermoplastic polyurethane nanofibers, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2013.09.028, Vol.49, pp.3851-3856, 2013

Streszczenie:

Analysis of the thermo-mechanical behavior of electrospun thermoplastic polyurethane (TPU) block co-polymer nanofibers (glass transition temperature ∼−50°C) is presented. Upon heating, nanofibers began to massively contract, at ∼70°C, whereas TPU cast films started to expand. Radial wide-angle X-ray scattering (WAXS) profiles of the nanofibers and the films showed no diffraction peaks related to crystals, whereas their amorphous halo had an asymmetric shape, which can be approximated by two components, associated with hard and soft segments. During heating, noticeable changes in the contribution of these components were only observed in nanofibers. These changes, which were accompanied with an endothermic DSC peak, coinciding with the start of the nanofibers contraction, can be attributed to relaxation of an oriented stretched amorphous phase created during electrospinning. Such structure relaxation becomes possible when a portion of the hard segment clusters, forming an effective physical network, is destroyed upon heating.

Słowa kluczowe:

Block-copolymer, Electrospinning, Nanofibers, Thermo-mechanical properties

Afiliacje autorów:

Alhazov D.-Technion - Israel Institute of Technology (IL)
Gradys A.-IPPT PAN
Sajkiewicz P.-IPPT PAN
Arinstein A.-Technion - Israel Institute of Technology (IL)
Zussman E.-Technion - Israel Institute of Technology (IL)
35p.

Abstrakty konferencyjne
1.Alhazov D., Gradys A., Denis P., Sajkiewicz P., Arinstein A., Zussman E., Thermo-mechanical behavior of electrospun thermoplastic polyurethane nanofibers, EPF2013, European Polymer Congress, 2013-06-16/06-21, Pisa (IT), pp.O2-23, 2013