Functional microparticles from multiscale regulation of multiphase emulsions for mass-transfer intensification

Designable microfluidic ladder networks from backstepping microflow analysis for mass production of monodisperse microdroplets

Controllable mass production of monodisperse droplets plays a key role in numerous fields ranging from scientific research to industrial application. Microfluidic ladder networks show great potential in mass production of monodisperse droplets, but their design with uniform microflow distribution remains challenging due to the lack of a rational design strategy. Here an effective design strategy based on backstepping microflow analysis (BMA) is proposed for the rational development of microfluidic ladder networks for mass production of controllable monodisperse microdroplets. The performance of our BMA rule for rational microfluidic ladder network design is demonstrated by using an existing analogism-derived rule that is widely used for the design of microfluidic ladder networks as the control group. The microfluidic ladder network designed by the BMA rule shows a more uniform flow distribution in each branch microchannel than that designed by the existing rule, as confirmed by single-phase flow simulation. Meanwhile, the microfluidic ladder network designed by the BMA rule allows mass production of droplets with higher size monodispersity in a wider window of flow rates and mass production of polymeric microspheres from such highly monodisperse droplet templates. The proposed BMA rule provides new insights into the microflow distribution behaviors in microfluidic ladder networks based on backstepping microflow analysis and provides a rational guideline for the efficient development of microfluidic ladder networks with uniform flow distribution for mass production of highly monodisperse droplets. Moreover, the BMA method provides a general analysis strategy for microfluidic networks with parallel multiple microchannels for rational scale-up.

Designable Micro-/Nano-Structured Smart Polymeric Materials

Smart polymeric materials with dynamically tunable physico-chemical characteristics in response to changes of environmental stimuli, have received considerable attention in myriad fields. The diverse combination of their micro-/nano-structural and molecular designs creates promising and exciting opportunities for exploiting advanced smart polymeric materials. Engineering micro-/nano-structures into smart polymeric materials with elaborate molecular design enables intricate coordination between their structures and molecular-level response to cooperatively realize smart functions for practical applications. In this review, recent progresses of smart polymeric materials that combine micro-/nano-structures and molecular design to achieve designed advanced functions are highlighted. Smart hydrogels, gating membranes, gratings, milli-particles, micro-particles and microvalves are employed as typical examples to introduce their design and fabrication strategies. Meanwhile, the key roles of interplay between their micro-/nano-structures and responsive properties to realize the desired functions for their applications are emphasized. Finally, perspectives on the current challenges and opportunities of micro-/nano-structured smart polymeric materials for their future development are presented.