(402h) Electrospinning Coacervates – No Chain Entanglements Required

Electrospun fibers are widely used in a number of different applications, such as biosensors and wound dressings. However, because electrospinning commonly involves the use of organic solvents, biocompatibility concerns can arise. To circumvent the challenge of organic solvents, we developed a fully aqueous strategy for electrospinning ultra-stable polyelectrolyte complex (PEC) fibers using complex coacervates. Coacervates are a dense, polymer-rich liquid phase resulting from the electrostatic complexation of oppositely charged macro-ions. The charge neutralization that results from this complexation is one of the aspects of coacervation that facilitates the electrospinning of charged polymers in water. In further considering the parameters that define the electrospinnability of complex coacervates, we hypothesized that the electrostatic attractions driving phase separation could facilitate electrospinning of extremely short polymers. This possibility dramatically contrasts the well-established paradigm for electrospinning, which dictates that physical chain entanglements are necessary to maintain a continuous jet during the spinning process. We investigated the spinnability and rheological characteristics of complex coacervates formed from poly(3-sulfopropyl methacrylate) (PSPMA) and poly([2-(methacryloyloxy)ethyl] trimethylammonium iodide (PTMAEMA) with degrees of polymerization of 20, 50, and 500. We were able to successfully electrospin complex coacervates formed from the shortest polymers, which had an average molecular weight of <5,000 g/mol (20-mers). Rheological characterization of coacervates made of different chain lengths in different salt concentrations correlated well to the electrospinnability of the solutions. These results suggest that the fully aqueous and associative nature of complex coacervation can be harnessed to enable the fabrication of new electrospun materials.