Electrospinning: production of fibers due the presence of small amounts of high molecular weight polymer in polydisperse and low concentration solutions

摘要

Fiber-spinning has become one of the major topic of research in recent year due to its ability to produce micro to nano meter thick fibers using polymer solutions at room temperatures and to form thick non-woven fabrics. These fabrics have potential applications in areas such as non-wetting and breathable clothing, wound dressing and template for growing artificial skin etc. Many techniques have been invented or rediscovered for making micro to nano meter thick fibers; examples are electro- spinning, spray-spinning, forced-spinning etc. During fiber production depending of the conditions, there can be only beads (without fibers), beads with fibers or just fibers. The control parameters that are important in producing only fibers (or predominantly fibers) are still not clear. A review of literature on this topic shows different parameters to be important. A few of these control parameters are the concentration (C) of polymer solution should be above the overlap concentration (C*), solution must have certain number of entanglements, should show extensional thickening, solution should be capable of forming a network etc. It is well know in literature that a polydisperse polymer solution gives fibers at concentrations well below C*. Recently we have shown, fibers can be produced by blending high concentration low molecular weight (Mw) polymer with low concentration high Mw polymer such that the effective Mw is similar to the polydisperse sample1. This experimental evidence points that the extensibility averaged molecular weight (ML ) and the extensibility averaged CL* might be a major factor that controls the fiber formation. In this talk we will discuss the results in terms of some of the above mentioned control parameters on fiber formation using a well-characterized PMMA solution.1. Siddarth Srinivasan, Shreerang S. Chhatre, Joseph M. Mabry, Robert E. Cohen, Gareth H. McKinley, Solution spraying of poly(methyl methacrylate) blends to fabricate microtextured, superoleophobic surfaces, Polymer 52 (2011) 3209-3218