Understanding hydrophobic interactions in cellulose nanofibres

This travel grant will enable Prof. Stephen Eichhorn (University of Bristol) to undertake collaborative work together with Prof. Tetsuo Kondo (Kyushu University, Japan) in the area of hydrophobic interactions in cellulose nanofibres. Cellulose is the most utilised material on the planet. Current annual production stands at a staggering 10^12 tonnes. Given its density this is about 20 times the volume of steel. It is primarily produced by plant cell walls but can also by some gram-negative bacteria and one known animal (tunicates). The structure of cellulose is such that chemical groups which decorate the sugar units making up the chains of the polymeric structure, are involved in hydrogen bonding - like in ice. This presents a dichotomy, in that although the basic sugars that make up cellulose are soluble in water, the polymer cellulose is not. This is usually attributed to the extensive hydrogen bonding present but given that the material will not dissolve in most solvents, this is now thought to not be the only contributing factor. Recently, the concept of a hydrophobic interaction (where two water 'hating' surfaces come together) within the cellulose structure, between the faces of the glucose rings, has been postulated - the so-called 'Lindman effect - as a limiting factor in its solvation. The hydrophobic effect itself is well-understood for relatively simple molecules, but for cellulose and complex macromolecules our understanding is still very much in development. Better understanding of this effect in cellulose could lead to greater exploitation of the material, particularly its use in composites by exploiting the inherent hydrophobicity of certain surfaces of a new form of cellulose nanofibre (a fibre with lateral dimensions <100nm). This form of cellulose nanofibre is produced by the group at Kyushu University using high pressure water jets - called Aqueous Counter Collision. The purpose of this grant is to form a collaboration to better understand the properties of this material. Professor Eichhorn currently has a large EPSRC funded program of research investigating the formation of hydrogels (EP/N03340X/2) using cellulose nanofibers; one potential area of exploitation is their use in composite materials. Professor Kondo has just received funding from NEDO (New Energy and Industrial Technology Development Organization)- Feasibility Study Program to study the interaction of thermoplastic polymers with cellulose. The work from these grants, combined with this travel, will enable the group to establish some new research lines in this area.

Immediate impact will be within the academic community, through dissemination of the results in good quality journal papers (e.g. Biomacromolecules, ACS Applied Materials & Interfaces and Cellulose). We also aim to disseminate our results through participation in conferences, such as the ACS' Cellulose and Renewable Materials Division and EPNOE. We will plan to propose symposia where we can disseminate these results. The International Cellulose Conference (ICC5) will be held in Japan in 2022, and we propose to present our work there also. Both Professors Eichhorn and Kondo are working closely with industry partners on their projects associated with this research, and it would be expected that with continuation funding, through the EPSRC-JSPS joint Core-To-Core programme that we would be able to have an impact on the production of new types of thermoplastic based composites. Following this travel grant we fully expect to be able to apply for additional funding to support these initiatives.