An assembly of polymer chains grafted on a surface is called a “polymer brush” because those form a brush-like thin layer with thickness of approximately 100 nm.
Surfaces of polymer brushes containing ionic functional groups are show super-hydrophilicity due to improving of the surface wettability. Therefore, the surfaces exhibit remarkable properties in water, such as oil-stain repelling (antifouling), protein-adsorption resistance (biocompatibility), and low coefficient of kinetic friction (lubricity).
Moreover, two surfaces grafting polymer brushes can be adhered by attaching with facing each other, and also can be detached by changing ambient conditions.
The polymer brushes are expected to be applied in a wide range of fields.
ポリマーブラシのイメージイラストと化学構造式
研究室ギャラリー
実験風景や観察された画像、研究に関わるイメージイラストを集めました。
銅触媒の還元反応 ―ポリマーブラシの調製のために―
Reduction of Cu catalyst for preparation of polymer brush by AGET ATRP
当研究室でポリマーブラシを調製するためによく使われる重合方法を紹介します。
We are going to introduce a polymerization method that is commonly used in our laboratory to prepare polymer brushes.
A reaction mixture 10 mL for the polymerization and a silicon substrate immobilized a polymerization initiator was added in this sealed test tube. This polymerization solution was prepared by dissolving copper(II) bromide CrBrCrBr2 as a catalyst, its ligand 2,2'-bipyridyl, and a methacrylic acid-type monomer containing a sulfonic acid group in a mixed solvent of methanol and water.
You can see an injection needle which was inserted in the solution and generated bubbles from its head. In this way, bubbles of nitrogen were provided to remove dissolved oxygen in the solution. This nitrogen bubbling had been preliminarily performed for 30 minutes.
Then, as you can see in this video, we inserted another injection needle from above and added an ascorbic acid aqueous solution (colorless and transparent). Immediately, the solution color changed from light blue to reddish brown. This is because the ascorbic acid reduced copper from divalent Cu2+ to monovalent Cu+ as written in a following half reaction.
Cu2+ + e− → Cu+
Firstly, the in-situ generated Cu+ activates the initiator immobilized on the silicon substrate. Then, this initiator reacts with the monomers one after another. This chain propagation produces the polymer brush grafting from the substrate.
In fact, the ascorbic acid is a very familiar reducing substance, also known as “vitamin C”. Using this reducing agent extremely simplify an experimental procedure because of avoiding the trouble of handling the unstable monovalent Cu+.
This polymerization method is called “Activators Generated by Electron Transfer (AGET)” for “Atom Transfer Radical Polymerization (ATRP)”.
Our laboratory can prepare various hydrophilic polymer brushes using AGET ATRP. We conduct a study on the unique characteristics of the polymer brush in a wide range such as the wettability, adhesion, adhesion, and lubrication.
Grafting technics of chain-like polymers on a surface provide the thin layer which is called the polymer brush. In particular, the hydrophilic polymer brush surfaces exhibit remarkable antifouling properties in water: such as repelling of oil stains and preventing of micro-organism settlements.
Two surfaces grafting polymer brushes can be adhered by attaching each other with a small amount of water, and also can be detached by changing ambient conditions. The new adhesion technique is eco-friendly because of organic-solvent free and be expected to be utilized for medical treatments.
Hydrophilic polymer brushes show excellent lubrication properties. The brushes consisting of biocompatible molecules are expected to be applied to coating on surfaces of catheters and artificial joints.
For surface modification, the polymer brushes can be prepared on various surfaces:
glass, silicon, alumina, metals – stainless and titanium, polymer materials – polyethylene, polycarbonate, polylactic acid, nylon, ABS resin, and polyimide, wood materials, and fibrous materials.
In addition, particles such as silica nanoparticles can be functionalized by grafting the polymer brushes for the purpose of improving the dispersibility and the compatibility to solvents.
利用・用途 / 応用分野
Application and purpose
超親水性表面 Super-hydrophilic surface
水中防汚性 Antifouling in water
海洋付着生物忌避 Repellent against sessile marine organisms
微粒子分散 Dispersion of nanoparticles
ブラシによる接着 Adhesion of polymer brushes
気泡のつかない表面 Anti-capturing air-bubbles
生物模倣表面 Biomimetics surface
電化製品の防汚処理 Antifouling treatment of electronic devices
太陽電池表面の防汚処理 Antifouling treatment of solar cells
フジツボ付着抑制 船底塗料 Antifouling ship-bottom paint against barnacle settlements
カテーテル表面のコーティング Coating on catheter surfaces
水潤滑と人工関節 Water lubrication and artificial joints
関連情報
Related information
知的財産権 | 特願2011-545211,他.
Intellectual property | Japan patent JP2011-545211, etc.
メディア関連 | NHK総合「凄ワザ!:汚れないまな板」2017年1月14日20:15-20:45放送
Media Coverage | NHK General TV, “Sugo-waza! The Antifouling Cutting Board” broadcasted on January 14, 2017, at 8:15-8:45 p.m.