Saleem Anwar and collaborators at the Max Planck Polymer Institute in Mainz, Germany, have developed an effective method for manufacturing ferroelectric nylon. This technology provides support for the inexpensive production of ferroelectric nylon films using commercial materials. Such films have a wide range of potential applications, including robotics, biomedical equipment, and energy harvesting.
As we all know, nylon is a synthetic material used in clothing, but some types of nylon have more complex applications. Nylon consists of repeating aliphatic units linked by amides. Aliphatic compounds are open-chain materials formed from carbon and hydrogen atoms, such as methane and ethylene.
Spontaneous polarization
The number of carbon atoms in the repeating aliphatic units of nylon gives it special properties. When the number is odd, nylon is a spontaneously polarized ferroelectric. Therefore, this nylon can be used to make capacitors. With its mechanical properties and ferroelectric properties, odd-numbered nylons are ideal for various applications.
According to the team, "It is a challenge to construct a smooth, optically transparent, and non-pinhole nylon film that crystallizes in the ferroelectric phase."
The team called this solution a low-cost technology that can be performed at room temperature. Nylon is insoluble in most common solvents, so the first step in nylon solution processing is to find a suitable solvent. Anwar and colleagues found that a mixture of trifluoroacetic acid (TFA) and acetone has the correct properties and can be used for solution processing of a small number of odd nylon films.
Ideal crystal phase
Nylon can solidify in different crystal phases, and ferroelectricity occurs only in one of these possible phases. This is the stage where the amorphous hydrogen-bonded chain structure polarizes the compound. Prior to this study, the ferroelectric phase of odd-numbered nylon was produced by solution treatment at room temperature.
Nylon film is made by spin coating the solution on the glass substrate. The sample is then quenched in solution under high vacuum, which will freeze the components in the tissue-free phase and remove residual solvent.
The authors compared the performance of ferroelectric nylon 11 capacitors; capacitors made of conventional ferroelectric polymers. This test focuses on the ability of the capacitor to maintain a polarized state when subjected to continuous stress cycles. In a million stress cycles, the performance of nylon 11 capacitors is better than traditional capacitors.