Macroscopic vertical alignment of nanodomains in thin films of semiconductor amphiphilic block copolymers

Sulfonated Block Copolymers: Synthesis, Chemical Modification, Self-Assembly Morphologies, and Recent Applications

Scientific research based on the self-assembly behavior of block copolymers (BCs) comprising charged-neutral segments has emerged as a novel strategy mainly looking for the optimization of efficiency in the generation and storage of electrical energy. The sulfonation reaction re- presents one of the most commonly employed methodologies by scientific investigations to reach the desired amphiphilic character, leading to enough ion concentration to modify and control the entire self-assembly behavior of the BCs. Recently, several works have studied and exploited these changes, inducing improvement on the mechanical properties, ionic conduction capabilities, colloidal solubility, interface activity, and stabilization of dispersed particles, among others. This review aims to present a description of recent works focused on obtaining amphiphilic block copolymers, specifically those that were synthesized by a living/controlled polymerization method and that have introduced the amphiphilic character by the sulfonation of one of the segments. Additionally, relevant works that have evidenced morphological and/or structural changes regarding the pristine BC as a result of the chemical modification are discussed. Finally, several emerging practical applications are analyzed to highlight the main drawbacks and challenges that should be addressed to overcome the development and understanding of these complex systems.

Topological Design of Highly Anisotropic Aligned Hole Transporting Molecular Bottlebrushes for Solution-Processed OLEDs

Polyvinyl polymers bearing pendant hole transport functionalities have been extensively explored for solution-processed hole transport layer (HTL) technologies, yet there are only rare examples of high anisotropic packing of the HT moieties of these polymers into substrate-parallel orientations within HTL films. For small molecules, substrate-parallel alignment of HT moieties is a well-established approach to improve overall device performance. To address the longstanding challenge of extension from vapor-deposited small molecules to solution-processable polymer systems, a fundamental chemistry tactic is reported here, involving the positioning of HT side chains within macromolecular frameworks by the construction of HT polymers having bottlebrush topologies. Applying state-of-the-art polymer synthetic techniques, various functional subunits, including triphenylamine (TPA) for hole transport and adhesion to the substrate, and perfluoro alkyl-substituted benzyloxy styrene for migration to the air interface, were organized with exquisite control over the composition and placement throughout the bottlebrush topology. Upon assembling the HT bottlebrush (HTB) polymers into monolayered HTL films on various substrates through spin-casting and thermal annealing, the backbones of HTBs were vertically aligned while the grafts with pendant TPAs were extended parallel to the substrate. The overall design realized high TPA π-stacking along the out-of-plane direction of the substrate in the HTLs, which doubled the efficiency of organic light-emitting diodes compared with linear poly(vinyl triphenylamine)s.

RAFT polymerization to form stimuli-responsive polymers

Stimuli-responsive polymers respond to a variety of external stimuli, which include optical, electrical, thermal, mechanical, redox, pH, chemical, environmental and biological signals. This paper is concerned with the process of forming such polymers by RAFT polymerization.

Efficient click-addition sequence for polymer–polymer couplings

Controlled radical polymerization methods and click chemistry form a versatile toolbox for creating complex polymer architectures.

High Molecular Weight Block Copolymers by Sequential Monomer Addition via Cu(0)-Mediated Living Radical Polymerization (SET-LRP): An Optimized Approach

The synthesis of well-defined high molecular weight block copolymers by sequential in situ chain extensions via Cu(0)-mediated living radical polymerization is reported. Optimal conditions for iterative high molecular weight block formation were determined using model homopolymer quasiblock systems, including methyl acrylate (MA), ethyl acrylate (EA), and n-butyl acrylate (nBA; each block DP_n ≈ 100). The PDI after each chain extension was below 1.2, with good agreement between theoretical and experimental molecular weights, while the conversion of monomer incorporation into each distinct block was 95-100% (up to 6 blocks). To demonstrate this approach for true block copolymer materials, well-defined block polymers containing MA, ethylene glycol methyl ether acrylate (EGMEA), and tert-butyl acrylate (tBA) were prepared in high purity: diblock P(MA-b-EGMEA) and triblock P(MA-b-tBA-b-MA). These were prepared in high yields, on multigram scales, and with purification only required at the final step. To the best of our knowledge, this is the first time that high molecular weight block copolymers have been reported using this novel technique.