Rice flour-based nanostructures via a water-based system: transformation from powder to electrospun nanofibers under hydrogen-bonding induced viscosity, crystallinity and improved mechanical property † Sarekha Woranuch, Autchara Pangon, Kantapat Puagsuntia, Nakarin Subjalearndee and Varol Intasanta * Rice flour is a naturally abundant and renewable biodegradable and biocompatible material. Nevertheless, fabrication of rice flour-based functional nanostructures has been challenging due to the difficulties in finetuning solution parameters. The present work shows a successful synthesis of rice-flour based nanofibers containing PVA by simply allowing rice flour and PVA to solubilize in alkaline conditions prior to electrospinning. Rice flour/PVA blend nanofibers at the rice flour weight content of 25% led to an optimal condition with reinforced hydrogen bonding between the two polymers. The interaction induced good processability and fiber formation with well-defined morphology. In addition, rice flour functioning as a nucleating agent promoted the crystallization of small PVA crystals resulting in an improvement of tensile strength and Young's modulus with respect to PVA nanofibers. This is for the first time showing not only the transformation of rice flour via a water-based system into mechanically robust nanofibers, but also the role of rice flour in inducing crystalline phase in semi-crystalline polymers in blends. The finding is important to bring in unprecedented practical applications for rice flour such as disposable nanofilters, tissue engineering scaffolds, wound dressings, etc.
IntroductionRice starch is a biopolymer obtained from rice our via an alkaline steeping method.1 Starch represents a unique class of polysaccharides due to its rich variety of amylose-amylopectin combinations. While amylose is a linear chain and amorphous part of starch granule, amylopectin constitutes a branched and crystalline component. The interplay between these two key components in a vast degree of amylose fraction lead to various types of rice showing different physical structure and mechanical performance.2,3 Starches have been of high demand due to their non-toxicity, biodegradability, biocompatibility, and ability to form lms, membranes, gels, and bers.
4-6Recently, nanobers have received much attention due to their applications in many areas such as high-performance lter media, sensors, medicine and medical textile materials.
7,8Various methods have been developed to fabricate nanomaterials, e.g. drawing, phase separation, self-assembly, template synthesis and electrospinning.9-12 Compared with other techniques, electrospinning could be applicable for a wide range of polymers, capable of controlling ber morphology with potential for scaling up production.Only a few works have investigated starch-based bers prepared through electrospinning technology. Kong and Ziegler 13 studied the preparation of pure corn starch bers by electro-wet-spinning. The result showed that starch bers had diameters in the order of mi...
