Highly Ordered Dielectric Mirrors via the Self-Assembly of Dendronized Block Copolymers

Abstract

Dendronized block copolymers were synthesized by ruthenium-mediated ring-opening methathesis polymerization of exo-norbornene functionalized dendrimer monomers, and their self-assembly to dielectric mirrors was investigated. The rigid-rod main-chain conformation of these polymers drastically lowers the energetic barrier for reorganization, enabling their rapid self-assembly to long-range, highly ordered nanostructures. The high fidelity of these dielectric mirrors is attributed to the uniform polymer architecture achieved from the construction of discrete dendritic repeat units. These materials exhibit light-reflecting properties due to the multilayer architecture, presenting an attractive bottom-up approach to efficient dielectric mirrors with narrow band gaps. The wavelength of reflectance scales linearly with block-copolymer molecular weight, ranging from the ultraviolet, through the visible, to the near-infrared. This allows for the modulation of photonic properties through synthetic control of the polymer molecular weight. This work represents a significant advancement in closing the gap between the precision obtained from top-down and bottom-up approaches.

Structure, function, self-assembly, and applications of bottlebrush copolymers

“…Grubbs et al studied the photonic properties of a series of PS/PLA bottlebrush block copolymer to understand the role of molecular weight and processing conditions on domain size 112 These assembled rapidly on solvent casting and exhibited a tuneable selective reflection band over a broad range of wavelengths 115 .…”

Thermomechanical Behavior and Local Dynamics of Dendronized Block Copolymers and Constituent Homopolymers

“…The synthesis of the homopolymers and BCPs used in the present study is described elsewhere. 7 The molecular weight, the polydispersity, and the lamellar spacing are listed in Table 1. The polymer films were deposited on glass slides, previously washed with methanol and hexanes, through controlled evaporation from dichloromethane (2 g/L).…”

“…Through minimizing the BCP's ability to engage in chain entanglement, the reorganization to large domain sized nanostructured materials is facilitated. 7 Specifically, we have been focusing on molecular brush and dendronized BCPs as a route to access one-dimensional photonic crystals through the self-assembly of BCPs. These copolymers consist of a polymeric main chain that unifies a densely packed array of bulky repeat units.…”

Side Chain Liquid Crystalline Polymers: Advances and Applications

“…With the consideration of the high tolerance of functional groups e.g. fullerene, the convenient synthesis by ring-opening metathesis polymerization (ROMP), (Ball et al 2006;Bielawski and Grubbs 2007) and the excellent properties of polynorbornenes, (Maier 2001;Piunova et al 2013), the exploration of MJLCPs with polynorbornene main chain, is of great interest (Zhu et al 2014). …”