Manipulation and Deposition of Complex, Functional Block Copolymer Nanostructures using Optical Tweezers

Block copolymer self-assembly has enabled the creation of a range of solution-phase nanostructures with applications from optoelectronics and biomedicine to catalysis. However, to incorporate such materials into devices a method that facilitates their precise manipulation and deposition is desirable. Herein we describe how optical tweezers can be used to trap, manipulate, and pattern individual cylindrical micelles and larger hybrid micellar materials. Through the combination of TIRF imaging and optical trapping we can precisely control the three-dimensional motion of individual cylindrical block copolymer micelles in solution, enabling the creation of customizable arrays. We also demonstrate that dynamic holographic assembly enables the creation of ordered customizable arrays of complex hybrid block copolymer structures. By creating a program which automatically identifies, traps, and then deposits multiple assemblies simultaneously we have been able to dramatically speed up this normally slow process, enabling the fabrication of arrays of hybrid structures containing hundreds of assemblies in minutes rather than hours

A facile photoinitiated polymerisation route for the preparation of photonic elastomers with chiral nematic order

Photonic crystal elastomers that can change colour upon stretching or compression have potential applications in mechanical sensors and optical coatings. However, facile synthetic strategies are required for these materials to be made on a commercially viable scale. To address this issue, we report a photoinitiated polymerisation method to prepare stretchable chiral nematic cellulose nanocrystal (CNC) elastomer composites that exhibit reversible visible colour upon the application of mechanical stress. The initial CNC-elastomer composite is colourless, but when it is stretched (or compressed), the helical pitch of the chiral nematic structure is reduced to lengths corresponding to the wavelengths of the visible region, resulting in colouration. By increasing the percentage elongation of the material (ca. 50–300%), the structural colour can be tuned from red to blue. The colour of the material was characterised by reflectance optical spectroscopy and reflectance circular dichroism to confirm the wavelength and polarisation of the reflected light.</p

Fluorous Cylindrical Micelles of Controlled Length by Crystallization-Driven Self-Assembly of Block Copolymers in Fluorinated Media

Fluorous solvents have recently found broad applications in medical treatments as well as catalytic transformations, yet the controlled self-assembly of nanomaterials in fluorinated media has remained a challenge. Herein, we report the synthesis of block copolymers containing a crystalline polyferrocenylsilane metalloblock and a highly fluorinated coil block and their controlled self-assembly in fluorinated media. Using the crystallization-driven self-assembly approach, cylindrical micelles have been prepared with controlled lengths and narrow length polydispersities by self-seeding. Finally, by partial functionalization of these block copolymers with fluorescent dye molecules, we show that well-defined, functional nanomaterials can be obtained in the fluorous phase