From crab and prawn shell to fabric with enhanced waterproofing
Nature has endowed the surface of a leaf with the fascinating property of waterproofing but can we also engineer waterproof materials made from natural origins?
A multidisciplinary international team from India and Singapore has successfully developed a simple method for producing superhydrophobic chitosan-based films-derived from the waste crab shell. Superhydrophobicity is a phenomenon whereby the contact angle of a water droplet on the film is observed to be greater than 150o, in other words, the film repels water.
Chitosan, one of the most abundant natural polysaccharide, is found as chitin in the shells of arthropods such as crabs and shrimp. The new superhydrophobic film is not only highly waterproof but also adequately strong and tough. When coated onto fabrics, it exhibits high durability. It can resist mechanical and hydrophobic deterioration under multiple cycles of laundry. Although high-temperature ironing action causes the superhydrophobicity to decrease, the effect is only temporary and any lost in superhydrophobicity can be recovered in no time.
The team revealed that the unique approach in the processing of the film involves blending the chitosan with octadecylamine and glutaraldehyde. The team is optimistic that this new low-cost sustainable coating approach could lend to applications in textile engineering as well in the other engineering industry from automotive engineering, construction, sports to biomedical engineering, including the waterproofing of single-use and reusable facemasks that are intended for protection against COVID-19.
Moreover, by applying the coating (or film) onto a standard hydrophilic polyurethane sponge, this provides the sponge with exceptional superhydrophobic and superoleophilic properties. This alteration enables the sponge to efficiently and swiftly absorb diverse organic solvents and oils, effectively separating them from oil/water mixtures. This means that such a sponge may be deployed on a large scale for cleaning up coastal water contaminated by oil, especially from an oil spill incident.
The team members are Dr. Roy Sunanda (GLA University, India), Dr. Chhavi Verma and Dr Pradip K Maji from Indian Institute of Technology Roorkee, Dr Barnali Dasgupta Ghosh from Birla Institute of Technology Mesra India, and Dr. Kheng Lim Goh from Newcastle University in Singapore.
The work has been published in ACS Sustainable Chemistry & Engineering [1] (DOI: https://doi.org/10.1021/acssuschemeng.2c00206). For further details and enquiry on potential collaboration, please contact Dr. Roy Sunanda at [email protected] (or [email protected]), or Dr K L Goh at [email protected].
References
[1] A Facile Method for Processing Durable and Sustainable Superhydrophobic Chitosan-Based Coatings Derived from Waste Crab Shell, by Sunanda Roy, Kheng-Lim Goh, Chhavi Verma, Barnali Dasgupta Ghosh,Pradip K. Maji, Kamal Sharma, ACS Sustainable Chem. Eng. 2022, 10, 14, 4694–4704
