Effects of Chain Conformation and Entanglement on the Electrospinning of Pure Alginate

Abstract

As a natural biopolymer, sodium alginate (SA) has been widely used in the biomedical field in the form of powder, liquid, gel, and compact solid, but not in the form of nanofiber. Electrospinning is an effective method to fabricate nanofibers. However, electrospinning of SA from its aqueous solution is still a challenge. In this study, an effort has been made to solve this problem and find the key reasons that hinder the electrospinning of alginate aqueous solution. Through this research, it was found that pure SA nanofibers could be fabricated successfully by introducing a strong polar cosolvent, glycerol, into the SA aqueous solutions. The study on the properties of the modified SA solution showed that increasing glycerol content increased the viscosity of the SA solution greatly and, meanwhile, decreased the surface tension and the conductivity of the SA solution. The rheological results indicated that the increase in glycerol content could result in the enhanced entanglements of SA chains. Two schematic molecular models were proposed to depict the change of SA chain conformation in aqueous solution with and without glycerol. The main contribution of glycerol to the electrospinning process is to improve the flexibility and entanglement of SA chains by disrupting the strong inter- and intramolecular hydrogen bondings among SA chains, then forming new hydrogen bondings with SA chains.

A review on electrospun bio-based polymers for water treatment

“…On the other hand, some solvents may be added either to increase [55,56] or decrease the electric properties of the spinning solution [12,19]. The most used solvents in electrospinning are shown in Table 1.…”

“…The most used solvents in electrospinning are shown in Table 1. Solvents with good volatility, moderate vapour pressure, moderate boiling point, good conductivity and good cohesion with the polymer is important in the electrospinning process [12,[56][57][58][59][60][61]. The solubility of the polymer, however, does not guarantee the solution spinnability [12].…”

“…They are categorized according to the monomeric units that build up the complex polymeric structure, namely polynucleids (ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)), polypeptides (proteins), and polysaccharides (cellulose, and chitosan). The electrospinnability of most biopolymers is still a challenge because of numerous factors [11][12][13][14][15]. These include their rigid structure, high conductivity, high surface tension, and their gelation at fairly low concentrations.…”

Green Synthesis: Nanoparticles and Nanofibres Based on Tree Gums for Environmental Applications

“…Electrospinning is one of the most proficient and sophisticated methods for the fabrication of nanofibres on a large scale and with a large surface area to volume ratio, high porosity and stability [19]. The electrospinning process parameters such as system and process variable requirements have been meticulously reported in the literature [20,21]. In order to develop 'green electrospinning' technology it is necessary to use non-toxic, cheap, and environmental friendly solvents and materials.…”

Biocompatible sodium alginate fibers by aqueous processing and physical crosslinking

“…Even at concentrations below gelation, insufficient polymer chains as well as intermolecular repulsion between anionic groups hinder chain entanglement required for fiber formation. Electrospinning of sodium alginate (SA) has only been possible from either solutions in organic solvents (Bhattarai et al, 2006;Nie et al, 2008) or aqueous mixtures containing synthetic water-soluble polymers, such as poly(vinyl alcohol) (PVA) (Islam & Karim, 2010;Lee et al, 2007;Safi, Morshed, Hosseini Ravandi, & Ghiaci, 2007;Shalumon et al, 2011) and poly(ethylene oxide) (PEO) (Alborzi, Lim, & Kakuda, 2010;Bhattarai et al, 2006;Bonino et al, 2011;Kong, Yu, Ji, & Xia, 2009;Lu, Zhu, Guo, Hu & Yu, 2006;Ma, Fang, Liu, Zhu, & Nie, 2012;Nie et al, 2009;Safi et al, 2007;Zhang, 2007). From aqueous media, uniform fibers with SA as the dominant polymer could only be electrospun from mixtures with PEO.…”