Control of Morphology in Polymer Blends through Light Self-Trapping: An in Situ Study of Structure Evolution, Reaction Kinetics, and Phase Separation

Abstract

We report on how polymer morphology is controlled through the self-trapping of transmitted optical beams in photoreactive polymer blends. Self-trapped optical beams, characterized by divergence-free propagation, drives the growth of a congruent arrangement of polymer filaments in the blends. With suitable component weight fractions and exposure intensity, binary phase morphologies form in precisely the same pattern as the beams’ arrangement, thereby producing 2D structures in polymer blend volumes of large depth and area. Morphology evolution and the formation processes were observed by in situ microscopy. In situ confocal Raman measurements of polymer conversion and molecular weight increase along the filament regions reveal that polymerization undergoes autoacceleration, followed by the onset of mixing instability which leads to phase separation. These phenomena begin at the front end of the filament and propagate along its length over the depth of the blend. Control over morphology is discussed with respect to the competitive processes of phase separation and photo-cross-linking.

Superhydrophobic Polymer Composite Surfaces Developed via Photopolymerization

“…However, the system is in a weakly cross-linked, sol–gel-type state wherein NP diffusion can still occur. 25 , 32 These results confirm the presence of NPs on the surface, and consequently, nanoscale roughness, which is necessary for imparting superhydrophobic properties to the otherwise hydrophilic polymer.…”

Direct Light‐Writing of Nanoparticle‐Based Metallo‐Dielectric Optical Waveguide Arrays Over Silicon Solar Cells for Wide‐Angle Light Collecting Modules

“…Raman Volume Mapping : 3D composition maps of the Ag nanoparticle distribution were generated by 3D mapping of the material's Raman spectra, as described previously, then rendering a 3D volume for a Raman peak for silver (994 cm −1 ).…”

“…The waveguide arrays are produced in a photo‐reactive blend of high and low refractive index polymers irradiated with arrays of microscale optical beams. Each beam undergoes self‐trapping owing to photopolymerization‐induced optical nonlinearity, resulting in divergence‐free propagation of the beams across the medium . The sustained polymerization in the regions of the optical beams results in photopolymerization‐induced phase separation of the low‐index polymer into the surrounding dark regions, thereby producing the core‐cladding architecture with cylindrical geometry, namely, a microscale fiber optic.…”

“…In this work, metallo‐dielectric waveguide array structures are produced by combining light‐induced self‐writing in a two‐component photopolymerizable blend with concurrent in situ synthesis of silver nanoparticles via photo‐reduction of a silver salt (AgSbF 6 ) . The waveguide array structures are processed directly over a silicon solar cell via casting the precursor resin and then irradiating the resin from above with an array of microscale UV optical beams, which undergo self‐trapping, making the approach easily integrated into the processing of modules.…”

Mechanochromic Fluorescent Polymers Enabled by AIE Processes

“…Traditional techniques for detecting mechano‐induced structural or morphological changes in polymers often relied on electron microscopies, such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. [ 4 ] Although these techniques have been widely used, they are generally expensive and time‐consuming. The sample preparation procedures are often troublesome and may irreversibly change the bulk sample structure.…”