Electrospinning branching

The following parameters and processing variables affect the electrospinning process (i) system parameters such as molecular weight, molecular weight distribution and architecture (branched, linear, etc.) of the polymer, and polymer solution properties (viscosity, conductivity, dielectric constant, and surface tension, charge carried by the spinning jet) and (ii) process parameters such as electric potential, flow rate and concentration, distance between the capillary and collection screen, ambient parameters... 

Electrospinning a polymer solution could produce thin fibers with a variety of cross-sectional shapes. Branched fibers, flat ribbons, ribbons with other shapes, and fibers that were split longitudinally from larger fibers were observed. The transverse dimensions of these asymmetric fibers were typically 1000 to 2000 nm, measured in the widest direction. The observation of fibers with these cross-sectional shapes from a number of different kinds of polymers and solvents indicated that fluid mechanical effects, electrical charge carried with the jet, and evaporation of the solvent all contributed to the formation ofthe fibers. ... 

The parameters involved in the electrospinning processes that affect the nanofiber geometry and structure can be divided into two groups (i) System parameters such as polymer molecular weight, molecular weight distribution, polymer architecture (branched, linear), concentration of the polymer solution and its properties, including viscosity, electrical conductivity, and surface tension and (ii) Process parameters such as applied electric voltage, polymer flow rate, distance between the needle tip and the collector, ambient parameters such as temperature, humidity, and air velocity in the chamber, and motion of the collector (Frenot and Chronakis 2003). 

Yarin A L, Kataphinan W and Reneker D H (2005) Branching in electrospinning nanofibers, J Appl Phys 98 064501. 

Figure 10.10 is reprinted from Journal of Applied Physics, Vol. 98, 2005, Authors Yarin A L, Kataphinan W and Reneker D H, Title Branching in electrospinning nanofibers, pp. 064501/1-12, Copyright (2005), with permission from Wiley Periodicals, Inc. 

Hydrogels are one of the most common tissue engineering scaffolds. In its most basic form, a hydrogel consists of a solution of hydrophilic polymer, suspended in water, that forms a gel on cross-linking. Cross-linking may be induced by a radical initiator, usually photo- or heat activated, which cross-links linear or branched polymers. As with electrospinning, there are many polymers and polymer blends that have been made into hydrogels (Li et al., 2015 Lin and Li, 2014 Sun et al., 2014). 

McKee, M. G., T. Park, S. Unal, I. Yilgor, and T. E. Long (2005). Electrospinning of linear and highly branched segmented poly(urethane urea)s. Polymer 46(7) 2011-2015. 

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