(518j) Bijel Helices Via Rotational Microfluidics

BIJELS stands for “Bicontinuous Interfacially Jammed Emulsion Gels” and is a type of material that has generated considerable interest in the scientific community due to its unique structure and properties [1]. BIJELS are composed of two immiscible fluids that form a Bicontinuous network of interconnected channels stabilized by an interfacial layer of colloidal particles. BIJELS have potential applications in variety of fields, including drug delivery, sensing, catalysis, tissue engineering, and passive cooling. Despite their potential, there is still much to learn about the fundamental properties of BIJELS and how they can be tailored for specific applications. STrIPS (Solvent Transfer Induced Phase Separation) is a relatively easier technique discovered to date to generate BIJELS in various shapes such as particles, fibers and membranes in a continuous fashion [2,3].

Our latest findings demonstrate the transformation of multiple STrIPS-BIJEL fibers into more complex helical arrangements. We investigated a microfluidic twisting method to fabricate micro-ropes of nanostructured BIJEL fibers [4]. This method shows how weak microfibers with tensile strengths of a few kPa can be reinforced by 4 orders of magnitude by means of microfluidic twisting. Microfluidic twisting allows to produce continuous BIJEL fiber ropes of controllable architecture. Modelling the fluid flow field reveals the rope geometry dependence on a subtle force balance composed of rotational and translational shear stresses. However, the direction of the centrifugal force determines whether microropes undergo undulation during microfluidic twisting. The undulation of ropes can be avoided by decreasing the density of the fiber casting mixture, or upon increasing the density of the co-flowing liquid, enabling a controlled and continuous collection of uniform microropes [5]. We envision this microfluidic twisting method to enable the fabrication of new composite materials with applications in flexible electronics, micro robotics, actuators, and tissue engineering.

References:

[2] K. Stratford, R. Adhikari, I. Pagonabarraga, J.C. Desplat, M.E. Cates, Science (2005)

[2] M.F. Haase, K. J. Stebe, D. Lee, Advanced Materials (2015)

[3] M.A. Khan, A.J. Sprockel, K.A. Macmillan, M.T. Alting, S.P. Kharal, S.B. Ansah, M.F. Haase, Advanced Materials (2022)

[4] S.P. Kharal, R.P. Hesketh, M.F. Haase, Advanced Functional Materials (2020)

[5] S.P. Kharal, M.F. Haase, Small (2022)