Method for measuring relaxation behaviors of counter ion pairs in polyelectrolyte brush

Abstract

The invention discloses a method for measuring relaxation behaviors of counter ion pairs in a polyelectrolyte brush. The method comprises the following steps: bonding an initiator to a gold chip by chemical reaction; chemically grafting a monomer onto the gold chip by a radical polymerization method to obtain a gold chip with a polyelectrolyte brush; putting the gold chip with the polyelectrolytebrush in a sample cell and soakng it with a solution; obtaining the relaxation frequency of the counter ion pairs inside the polyelectrolyte brush in the solution by cooperatively using an electrochemical workstation and a quartz crystal microbalance electrochemical module. By adopting the method of cooperatively using the electrochemical workstation and the quartz crystal microbalance electrochemical module and by grafting the polyelectrolyte brush on the gold chip, on one hand, a quartz crystal microbalance can be utilized to measure the mass and viscoelasticity changes of polyelectrolyte brush films in different sodium chloride solutions in real time; on the other hand, the electrochemical workstation can also be utilized to simultaneously measure the relaxation behaviors of the counterion pairs inside the polyelectrolyte brush in the different solutions.

Description

Technical field [0001] The invention relates to a method for measuring the relaxation behavior of counter ion pairs inside a polyelectrolyte brush, and belongs to the field of condensed matter physics. Background technique [0002] The polyelectrolyte brush refers to a dense film formed by grafting one end of a charged polymer onto a flat or spherical surface. Polyelectrolyte brushes are believed to have a wide range of applications in people's daily lives, for example, artificial bone joint lubrication, anti-fouling, anti-ice adhesion, etc. Although polyelectrolyte brushes have a wide range of applications, people have not yet obtained a completely clear picture about the distribution of ions in the polyelectrolyte brush, the structure of the chain segments, and the interaction between ions and the chain segments. [0003] As early as 1991, Pincus (Macromolecules 1991, 24, 2912.) used the mean field theory to predict the response behavior of polyelectrolyte brushes to external sa...

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Problems solved by technology

However, due to the different focus, these experimental phenomena were ignored

Later, Dr. Chu Yu (Soft Matter 2014, 10, 5568) also discovered the same phenomenon that the thickness of the polyelectrolyte brush would increase under low salt concentration. In the paper, he gave a detailed description of the thickness change The explanation is that the interaction between the internal ion pairs binds the relaxation of the polymer chain segment. When an external salt enters, the interaction between the ion pairs will be broken, resulting in an increase in the thickness of the polyelectrolyte brush.

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