Integration of Polymer Synthesis and Self‐Assembly for Controlled Periodicity and Photonic Properties

Abstract

Materials chemistry and self‐assembly properties are usually treated separately, largely limiting the real‐time control of their nanostructures and resulting macroscopic properties in advanced self‐assembled materials. This study shows a model system that integrates synthesis and self‐assembly to achieve controlled periodicity and photonic properties in block copolymers (BCPs) at defined locations. First, the BCP thin films containing a pre‐dissolved photo‐initiator are swollen with monomer vapors. Upon exposure to UV light, the photoreaction synthesizes homopolymers within the film, which simultaneously blend with the BCPs and modify the periodicity in the exposed regions. This technique is successfully adapted to cylindrical polystyrene‐b‐polyisoprene‐b‐polystyrene and lamellar polystyrene‐b‐poly(2‐vinyl pyridine) BCP thin films. This capability is especially useful in the practical application of photonic crystals, where it is shown that the stop band position of polystyrene‐b‐quaternized‐poly(2‐vinyl pyridine) photonic gel films can be successfully modulated in situ. A large‐scale pattern is then fabricated by using a photomask. This study provides a model system for integrating materials synthesis and self‐assembly to achieve spatially defined control over structural periodicity and macroscopic properties in self‐assembled materials.

Synthesis and Study of the Optical Properties of PMMA Microspheres and Opals

“…From the data in Table 4 , we note that the calculated solid volume fractions exceed the theoretical value of 0.74 for an fcc sphere from hard materials. This is probably because PMMA spheres are considered soft material spheres [ 42 ].…”

Recent Advances in Block Copolymer Self‐Assembly for the Fabrication of Photonic Films and Pigments

“…Beyond developing new methods to tune PS-b-P2VP, such as applying vapor-or liquid-phase infiltration, [116,117] recent studies have also explored more novel LBCPs and their application in photonic materials. A notable example is polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) by Gallei and co-workers.…”

Developing Anisotropy in Self‐Assembled Block Copolymers: Methods, Properties, and Applications

“…While numerous efforts have been pursued to achieve a perfect "single-crystal" morphology over the entire substrate, many applications actually require complex nanopatterns, meaning fabricating regions that contain different features on one substrate with each region being locally aligned. [296,[546][547][548][549][550] Kinetic trapping of a nonequilibrium morphology in a local area with assistance from lithographic patterning provides some degree of flexibility to alter local structure orientation and/or degree of order, but such methods may not be able to produce a highly diverse nanopattern. Alternatively, selective deposition of different BCPs on different regions can lead to a hierarchical nanopattern, but it becomes more challenging when the complexity of final patterning increases since each BCP corresponds to only one fixed size and morphology.…”

“…[477,[551][552][553][554][555][556][557] Recently, an in-film polymerization approach is demonstrated to enable local production of homopolymers within a BCP film matrix in order to alter nanostruc-tures (both size and morphology) with simultaneous improvement of the degree of ordering from monomer vapors, leading to distinct morphologies on one substrate when a photomask is applied. [549,550] While this in-film polymerization is still limited with a batch process, this approach opens a new avenue for on-demand nanopattern manipulation over a defined area. Moving forward, it is likely that combining in-film polymerization with other previously established aligning techniques would enable exact registration of local nanostructures over different regions.…”