Block Copolymer Colloidal Particles with Unique Structures through Three-dimensional Confined Assembly and Disassembly

Structured block copolymer(BCP) particles have gained increasing attention due to their potential applications in separation,catalysis, controlled release, and other fields. Three-dimensional(3D) confined assembly has been proved as a facile yet robust approach for generating BCP particles with controllable shapes and internal structures. In this feature article, we summarized the preparation of structured polymeric particles through 3D confined self-assembly of BCPs. The effects of interfacial interactions, degree of confinement,and additives on the shape and internal structure of BCP microparticles were comprehensively discussed. In addition, we highlighted the recent progress in using disassembly as a route to synthesize colloidal particles with unique structures. Two strategies were introduced in this part:(a) disassembling the discrete domains resulted in mesoporous microparticles;(b) disassembling the continuous domains led to the dissociation of microparticles into micelle-like nano-objects. The applications of the structured colloidal particles in photonic crystals,controlled release, and directed growth of inorganic materials were also presented. Finally, we discussed the current challenges and future opportunities in this promising area.

Cotunneling transport in ultra-narrow gold nanowire bundles

We investigate the charge transport in close-packed ultra-narrow （1.5 nm diameter） gold nanowires stabilized by oleylamine ligands. We give evidence of charging effects in the weakly coupled one-dimensional （1D） nanowires, monitored by the temperature and the bias voltage. At low temperature, in the Coulomb blockade regime, the current flow reveals an original cooperative multi-hopping process between 1D-segments of Au-NWs, minimising the charging energy cost. Above the Coulomb blockade threshold voltage and at high temperature, the charge transport evolves into a sequential tunneling regime between the nearest- nanowires. Our analysis shows that the effective length of the Au-NWs inside the bundle is similar to the 1D localisation length of the electronic wave function （of the order of 120 nm _＋ 20 nm）, but almost two orders of magnitude larger than the diameter of the nanowire. This result confirms the high structural quality of the Au-NW segments.

Soft electrostatic trapping in nanofluidics

Trapping and manipulation of nano-objects in solution are of great interest and have emerged in a plethora of fields spanning from soft condensed matter to biophysics and medical diagnostics.We report on establishing a nanofluidic system for reliable and contact-free trapping as well as manipulation of charged nano-objects using elastic polydimethylsiloxane(PDMS)-based materials.This trapping principle is based on electrostatic repulsion between charged nanofluidic walls and confined charged objects,called geometry-induced electrostatic(GIE)trapping.With gold nanoparticles as probes,we study the performance of the devices by measuring the stiffness and potential depths of the implemented traps,and compare the results with numerical simulations.When trapping 100 nm particles,we observe potential depths of up to Q≅24 k_(B)T that provide stable trapping for many days.Taking advantage of the soft material properties of PDMS,we actively tune the trapping strength and potential depth by elastically reducing the device channel height,which boosts the potential depth up to Q~200 k_(B)T,providing practically permanent contactfree trapping.Due to a high-throughput and low-cost fabrication process,ease of use,and excellent trapping performance,our method provides a reliable platform for research and applications in study and manipulation of single nano-objects in fluids.