Selectively Dissolvable Biopolymer Interface for Textile Recycling

Although usually only accounting for about 1% of the composition of blended materials, 80% of discarded garments in the US contain spandex fibers. Blended spandex fibers are notoriously difficult to reprocess through traditional mechanical and chemical recycling methods. Here, we propose the design of a dissolvable interface layer of chitosan to facilitate spandex separation from blended fabrics through selective dissolution, a common chemical recycling method. In this study, chitosan, an antibacterial biodegradable biopolymer, is coated onto spandex filaments via dip coating. A lab-scale dip-coating and drying process was developed for this study based on limitations of the physical properties of the spandex filaments and the literature available for liquid coating of a fiber. We investigate the relationship between dip coating parameters and final morphology of the chitosan coating and find that both chitosan molecular weight and concentration greatly affect coating thickness. Using FT-IR spectroscopy, we also uncover indications of strong non-covalent interactions between the chitosan coating and spandex filament, suggesting good interfacial adhesion. This work represents foundational knowledge in the development of alternative blended spandex fibers to facilitate textile recycling.

Acknowledgement – This work was supported by the MIT Materials Initiative for Comprehensive Research Opportunity (MICRO) and by the Northwestern University MRSEC REU program funded by the NSF.