ABSTRACT
Direct conversion of light into mechanical work, known as the photomechanical effect, is an emerging field of research, largely driven by the development of novel molecular and polymeric material systems. However, the fundamental impediment is that the previously explored materials and structures do not simultaneously offer fast and wavelength-selective response, reversible actuation, low-cost fabrication and large deflection. Here, we demonstrate highly versatile photoactuators, oscillators and motors based on polymer/single-walled carbon nanotube bilayers that meet all the above requirements. By utilizing nanotubes with different chirality distributions, chromatic actuators that are responsive to selected wavelength ranges are achieved. The bilayer structures are further configured as smart 'curtains' and light-driven motors, demonstrating two examples of envisioned applications.
ABSTRACT
Microreactors are an emerging technology for the controlled synthesis of nanoparticles. The Multi-Temperature zone Microreactor (MTM) described in this work utilizes thermally isolated heated and cooled regions for the purpose of separating nucleation and growth processes as well as to provide a platform for a systematic study on the effect of reaction conditions on nanoparticle synthesis.
ABSTRACT
Soft lithography methods are emerging as useful tools for high-resolution, three-dimensional patterning of polymers and nanoparticles. However, the low Young's modulus of the standard template material, poly(dimethylsiloxane) (PDMS), limits attainable resolution, fidelity, and alignment capability. While much research has been performed to find other more rigid polymer template materials, the high solvent and vapor permeability that is characteristic of PDMS is often sacrificed, preventing their use in those processes reliant on this property. In this work, a highly rigid, chemically robust, optically transparent and vapor-permeable poly(4-methyl-2-pentyne) template is developed. The combination of high rigidity and high vapor permeability enables high resolution patterning with simplified ink handling. This material was nanopatterned to create a template for patterning polymers and nanoparticles, achieving a resolution of better than 350 nm.
Subject(s)
Crystallization/methods , Dimethylpolysiloxanes/chemistry , Molecular Imprinting/methods , Nanostructures/chemistry , Nanostructures/ultrastructure , Polyenes/chemistry , Elastic Modulus , Gases/chemistry , Hardness , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Porosity , Surface PropertiesABSTRACT
A novel microfluidic molding process was used to form microscale features of gold nanoparticles on polyimide, glass, and silicon substrates. This technique uses permeation pumping to pattern and concentrate a nanoparticle ink inside microfluidic channels created in a porous polymer template in contact with a substrate. The nanoparticle ink is self-concentrated in the microchannels, resulting in dense, close-packed nanoparticle features. The method allows for better control over the structure of printed features at a resolution that is comparable to inkjet printing, and is purely additive with no residual layers or etching required. The process uses low temperatures and pressures and takes place in an ambient environment. After patterning, the gold nanoparticles were sintered into continuous and conductive gold traces.
