Soybean Oil Based Fibers Made Without Solvent or Heat

Abstract

Thiol–ene chemistry was harnessed to enable production of thermochemically stable thermoset fibers containing 50–87 wt % acrylated epoxidized soybean oil and 49–72% biobased carbon without using solvent or heat. In this demonstration, the fibers were made by simultaneous electrospinning and photocuring of a liquid monomer mixture, which could be translated to other fiber manufacturing processes such as melt blowing or Forcespinning. Scanning electron micrographs illustrate the fiber quality and an average diameter of about 30 μm. Photochemical conversion kinetics of functional groups during light exposure were measured by real-time Fourier transform infrared spectroscopy, providing insight into the advantages of using high-functionality monomers and thiol–ene chemistry in this application.

Manipulating characteristic timescales and fiber morphology in simultaneous centrifugal spinning and photopolymerization

“…A useful way to describe the curing kinetics of a cross-linked network is by its gel point, the point at which a continuous, crosslinked network is formed and the gel time (T gel ), the time for a monomer mixture to reach the gel point. According to the gelation theory developed by Bowman and coworkers, the gel point of a mixed chain growth and step growth cross-linked network such as the one under investigation in this report can be calculated using the equation below [20,38]:…”

“…where r is the stoichiometric ratio of thiol to ene, f ene and f SH are the functionality of ene and thiol monomer, respectively, p a is the gel point in terms of degree of acrylate conversion, and k CC /k CS is the ratio of the propagation constant for acrylateeacrylate reactions to the chain transfer constant of acrylateethiol reactions, which has been previously reported to be around 1.5 [20,38,39]. The gel point was calculated to be 2.2% of the acrylate double bond conversion.…”

“…The gel point was calculated to be 2.2% of the acrylate double bond conversion. The double bond conversion over time was tracked by the reduction of the peak area of the acrylate group at 1636 cm À1 [19,20,40]. Fig.…”

“…In this method, a mixture containing monomers and a photoinitiator was simultaneously electrospun and photopolymerized via UV initiated thiol-ene chemistry to produce solid fibers in ambient conditions. The method was also made even greener by replacing more than 50 wt% of petroleum based monomer with a bio-renewable soybean oil derived monomer without sacrificing the final fiber quality [20]. Despite the very limited curing time during the fiber spinning process, the fibers made by this method contained a highly crosslinked network, which imparted high thermal stability, chemical resistance, and mechanical strength to the resulting fibers [19].…”

Schwefel in der modernen Materialwissenschaft

“…Neben der Anwendung der Mikrofluidik zur Herstellung von Fasern wurden zur Herstellung von Thiol‐En‐Fasern auch andere Methoden demonstriert . Insbesondere beschrieben Ellison und Mitarbeiter die Herstellung von Thiol‐En‐Fasern mittels Elektrospinnen, unter anderem von Fasern auf der Basis von Sojabohnenöl …”