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A microfluidic approach is described for generating capsules of biopolymer hydrogels at room temperature and with good control of particle size distribution and internal structure. The time of gelation and/or the concentration of the cross-linking agent in the continuous phase are controlled in order to achieve control over the internal structure of biomicrogels from capsules to gradient microgels to microgels with a uniform structure.

The internal trigger approach is applied for multistep microfluidic polymerization reactions conducted in droplets, namely, polyaddition and polycondensation. The microfluidic synthesis has helped in conducting efficient screening of the compositions of the monomer mixtures and for producing polymer particles with a narrow size distribution and a predetermined size.

A predefined self-organization of gold nanorods (NRs) end-terminated with multiple polymer arms ('pom-poms') is described in higher-order structures. The superposition of the two variables controlling the organization of NR has helped in creating a map showing the variation in the longitudinal plasmonic bands of the NRs achieved by their self-assembly.

Fast continuous synthesis of Janus particles (JPs) and three-phase particles with narrow size distribution or ternary particles is effected by a microfluidic method, which includes emulsification of monomer liquids and in-situ photoinitiated polymerization of multiphase droplets. The strategy for precise control over the structure of JPs and their structure-dependent assembly in clusters is presented, demonstrating an asymmetric chemical modification of the surface of JPs by conjugating them with protein molecules.

An approach for the continuous and scalable production of core-shell droplets and polymer capsules in microfluidic devices is reported. Polymer particles of various shapes and morphologies were obtained by photopolymerization of the monomeric shells.

We report the results of a systematic study of the effect of the surface energy of the walls of microchannels on emulsification in parallel flow-focusing microfluidic devices. We investigated the formation of water-in-oil (W/O) and oil-in-water (O/W) emulsions and found that the stability of microfluidic emulsification depends critically on the preferential wetting of the walls of the microfluidic device by the continuous phase. The condition for stable operation of the device is, however, different than that of complete wetting of the walls by the continuous phase at equilibrium. We found that W/O emulsions form when the advancing contact angle of water on the channel wall exceeds 92°. This result is unexpected because at equilibrium even for 92°) is thus more stringent than the equilibrium conditions. Conversely, we observed the stable formation of O/W emulsions for < 92°, that is, when the nonequilibrium transition to complete wetting by oil takes place. These results underlie the importance of pinning and the kinetic wetting effects in microfluidic emulsification. The results suggest that the use of parallel devices can facilitate fast screening of physicochemical conditions for emulsification. [ABSTRACT FROM AUTHOR]