Achieving directed motility and separation of colloidal particles is a crucial requirement in a range of technological areas. Herein, we describe a system that exploits the photothermal properties of plasmonic nanoparticles for the assembly and separation of larger microparticles. Irradiating an aqueous suspension of gold or silver nanoparticles with UV light generates thermal convection which can be used to move and organize larger particles. Moving the UV light source allows the relocation of the particle cluster. In addition, thermal convection can be used to separate inert particles of different sizes on an inclined plane. Since fluid motion stems from thermal convection, collection and separation can be reversed simply by turning off the UV light enabling a rapid on‐demand response system.

We present the synthesis, characterization and radical ring-opening polymerization (rROP) capabilities of thionoisochromanone (TIC), a fungi-derivable thionolactone. TIC is the first reported thionolactone to readily homopolymerize under free radical conditions without the presence of a dormant comonomer or repeated initiation. Even more, the resulting polymer is fully degradable under mild, basic conditions. Computations providing molecular-level insights into the mechanistic and energetic details of polymerization identified a unique S,S,O-orthoester intermediate that leads to a sustained chain-end. This sustained chain-end allowed for the synthesis of a block copolymer of TIC and styrene under entirely free radical conditions without explicit radical control methods such as reversible addition-fragmentation chain transfer polymerization (RAFT). We also report the statistical copolymerization of ring-retained TIC and styrene, confirmed by elemental analysis and energy-dispersive X-ray spectroscopy (EDX). Computations into the energetic details of copolymerization indicate kinetic drivers for ring-retaining behavior. This work provides the first example of a sustainable feedstock for rROP and provides the field with the first six-membered monomer susceptible to rROP, expanding the monomer scope to aid our fundamental understanding of thionolactone rROP behavior.

Illuminating an aqueous solution of plasmonic gold or silver nanoparticles with ultraviolet (UV) light generates convective flows. These convective flows can be harnessed to move, assemble, and separate larger microparticles on an incline. More information can be found in the Communication by Anna C. Balazs, Ayusman Sen et al.