Key parameters for the selection of composite conductive polymer material structure and conductive material silver coated copper powder

Conductive polymer materials are polymer materials with conjugated main electron systems in the main chain, which can be doped to achieve a conductive state with a conductivity of over 1000S/cm. After 40 years of development, people have conducted in-depth research on the types and mechanisms of conductive polymers, as well as how to improve their conductivity. Various explorations have been made on the synthesis and application of conductive polymers. Due to its unique properties, conductive polymers are not only widely used as conductive materials, but also have potential application value in fields such as energy, optoelectronic devices, sensors, and molecular wires.

The Conductive Mechanism of Conductive Polymer Materials

Composite conductive polymer material

The dispersion state of fillers in composite conductive polymer materials determines the conductivity of the material. From the percolation theory, it can be seen that when isolated and dispersed filler particles are loosely filled in the material, a continuous conductive path may be formed when the volume dispersion reaches a certain critical content. At this point, ions are in two states: one is that charge carriers can flow continuously inside the conductor, and physical contact occurs between ions; Secondly, due to the presence of a thin layer of adhesive between ions, the carriers themselves are activated and move. So, the condition for composite conductive polymer materials to conduct electricity is that the filling material should be dispersed to a certain extent and form a loose network distribution.

The composition of the filler material, the dispersion state of the filler particles, and their interaction with the polymer matrix in composite conductive polymer materials all determine the conductivity of the composite material. In order for the material to have better conductivity, it is necessary to ensure that the filler particles can be well dispersed and form a three-dimensional network structure or honeycomb structure.

Structural conductive polymer materials

In ionic conductive polymer materials, large molecular chains such as polyether and polyester form a helical spatial structure, and cations coordinate and complex with them. Under the promotion of the movement of large molecular chain segments, cations migrate through vacancies in their helical channels, or cations and anions dissolved by large molecules undergo transition diffusion between the gaps of the large molecular chain.

In electronic conductive polymer materials, most of the main polymer is a conjugated system, and the π - bonds in the long chain have high electron activity, especially after forming charge transfer complexes with dopants, they are easily released from the orbitals to form free electrons.

The π electrons within and between polymer chains can form conduction bands due to orbital overlap, providing channels for the transfer and transition of charge carriers. Under the influence of external energy and the vibration of the polymer chain, current can be conducted.

Classification of Conductive Polymer Materials Conductive polymer materials can be divided into two categories: composite materials and structural materials based on their production methods and structures. Although these two types of materials have similar characteristics, there are also significant differences, and their application directions and scopes are also different.

Composite conductive polymer material

It is made by filling composite, surface composite or layered composite of general polymer materials and various conductive substances. The main varieties include conductive plastics, conductive rubber, conductive fiber fabrics, conductive coatings, conductive adhesives, and transparent conductive films. Its performance is closely related to the type, dosage, particle size, and state of conductive fillers, as well as their dispersion state in polymer materials. Common conductive fillers include carbon black, metal powder, metal foil, metal fiber, carbon fiber, etc.

Structural conductive polymer materials

It refers to polymer materials that have conductive properties either by themselves or after doping. According to the conductivity, it can be divided into polymer semiconductors, polymer metals, and polymer superconductors. According to the conductive mechanism, it can be divided into electronic conductive polymer materials and ion conductive polymer materials.