The chemists from RUDN University have developed a new polyethylene production technology which can help in producing more durable and flexible material. The new technology made it possible to double the length of ethylene chains in comparison with those obtained by existing methods for polymers synthesis. The chemists synthesized new types of reagents to achieve this.
Synthesizing Longer Ethyl Chains
The chemists proposed changing the chemical composition of substances involved in the reactions in order to synthesize longer ethyl chains, which would mean stronger polyethylene, without resorting to an increase in the reaction temperature.
The chemists were able to synthesize three complexes of catalysts that included neodymium atoms. During the polymerization reaction, they interacted with magnesium atoms, which is a part of the initiating agent of the reaction.
Experimentation with Reaction Initiating Agent
The scientists began experimenting with a widely used magnesium-based reaction initiating agent, which ensures the growth of ethylene chains at low (below 100 °C) temperatures. It consists of four alkyl groups, two for each magnesium atom. The use of this agent in the polymerization reaction at a temperature of 40 °C allowed the chemists to obtain five chains of ethylene with a length of 16-20 molecules. By increasing the temperature of the solution to 80 °C, scientists obtained ethylene chains of 70-150 molecules in length. However, these chains turned out to be unstable and tend to split into short components.
The researchers came to the conclusion that to synthesize both long and stable ethylene chains it is necessary not to change the physical parameters (pressure and temperature) of the reaction, but to use a different reaction initiating agent, so that each alkyl group is bound to only one magnesium atom. Researchers managed to create such an agent and start the polymerization reaction with it. As a result of the experiment, the scientists obtained three polyethylene chains up to 46 molecules long at 40 °C. The obtained samples of polyethylene were more flexible and durable compared to those that were created using current techniques.
Longer and Strong Polyethylene Chains
All three catalysts, in combination with the new initiating agent the researchers created, gave similar results: Polyethylene chains up to 46 molecules in length. It was confirmed not only by test results, but also by the molecular model developed.
The polyethylene sample synthesized by the new method turned out to be more durable and flexible in comparison with the polyethylene created based on an ordinary reaction initiating agent. The technology has prospects for industrial applications in the production of plastic for food and bio-prostheses.
Source: RUDN University