Electrochemically Mediated Atom Transfer Radical Polymerization from a Substrate Surface Manipulated by Bipolar Electrolysis: Fabrication of Gradient and Patterned Polymer Brushes

Fabrication of Gradient and Patterned Organic Thin Films by Bipolar Electrolytic Micelle Disruption Using Redox-Active Surfactants

Bipolar electrochemistry could be regarded as a powerful approach for selective surface modification due to the beneficial feature that a wirelessly controllable potential distribution on bipolar electrodes (BPEs). Herein we report a bipolar electrolytic micelle disruption (BEMD) system for the preparation of shaped organic films. A U-shaped bipolar electrolytic system with a sigmoidal potential gradient on the BPE gave gradient-thin films including various interesting organic compounds, such as a polymerizable monomer, an organic pigment and aggregation induced emission (AIE) molecules. The gradient feature was characterized by UV-Vis absorption, thickness measurements and surface morphology analysis. Corresponding patterned films were also fabricated using a cylindrical bipolar electrolytic setup that enables site-selective application of the potential on the BPE. Such a facile BEMD approach will open a long-term perspective with respect to organic film preparation.

Surface Grafting "Band-Aid" for "Everyone": Filter Paper-Assisted Surface-Initiated Polymerization in the Presence of Air

We report herein a facile and generalized approach to the modification of solid surfaces with polymer brushes under ambient conditions: filter paper-assisted surface-initiated Cu0 -mediated controlled radical polymerization (PSI-CuCRP). The polymerization solution wetted filter paper is sandwiched between a copper plate and an initiator-modified substrate, which allows the creation of a surface-initiated polymerization (SIP) "band-aid" so that everyone can perform the surface grafting selectively with good control over the quality of the polymer brushes employing low concentration and microliter amounts of the monomer solution. The versatility of this method is demonstrated by grafting different homo-, block-, and multicomponent polymer brushes by using the same activation system and reaction conditions, the polymerization process can be precisely controlled to yield uniform polymers and show high chain-end functionality which is exemplified by in situ tetra-copolymerization. The combination of photolithography and paper cutting enables to prepare arbitrary three-dimensional patterned polymer brushes on the surface.

Capillary Microfluidic-Assisted Surface Structuring

A facile and universal oxygen-tolerant, capillary microfluidic-derived, controlled radical polymerization for surface structuring (gradient and patterned polymer brushes) is reported. A syringe pump and a filter paper sheet are used as capillary microfluidic to supply the reaction solution (monomer, solvent, and ligand) to a sandwich-shaped setup by placing a flat copper plate onto an ATRP initiator-modified substrate and resulting in gradient polymer brush formation with controlled thickness, steepness, and grafting area, polymers are showing the high chain-end fidelity. Two different polymer brushes (binary polymer brushes) can be simultaneously grown from both ends of the initiator modified substrate by using this method, which can be used to study the interfacial properties of different polymer brushes.

Oxo-Thiolation of Cationically Polymerizable Alkenes Using Flow Microreactors

The present study describes the cationic oxo-thiolation of polymerizable alkenes by using highly reactive cationic species generated by anodic oxidation. These highly reactive cations were able to activate alkenes before their polymerization. Fast mixing in flow microreactors effectively controlled chemoselectivity, enabling higher reaction temperatures.

Electro-Controlled Living Cationic Polymerization

Cationic polymerizations have long been industrialized; however, stimulus-regulated cationic polymerization remains to be developed. An electrochemically controlled living cationic polymerization is presented for the first time. In the presence of external potential and organic-based electrocatalyst, a series of monomers can be polymerized under a cationic chain-transfer mechanism. The resulting polymers exhibit well-defined molecular mass, narrow dispersity, and good chain-end fidelity. By controlling the external potential to switch the electrocatalyst between its oxidized and reduced states, ON/OFF polymerization can be achieved. This method is a versatile way to a large range of monomers, including vinyl ether-type and p-substituted styrene-type monomers. Given the sustainability feature and broad interest of electrochemical synthetic techniques, we envisaged that this method would lead a new direction of external regulated living ionic polymerization.