Schematic illustration showing the spontaneous synthesis of a homogeneous thermoresponsive polymer network composed of narrow molecular weight distribution polymers. Image: Yukikazu Takeoka.Polymer gel materials have found applications in medicine, civil engineering, architecture and space exploration. Their appeal lies in the potential for synthesizing functional materials with consistent properties via simple and easily reproducible methods. But the compromise between method simplicity and optimized material performance means that not all gel materials fulfil their potential.
Now, a group of researchers at Nagoya University in Japan has established a process that combines a spontaneous synthesis process with the high molecular weight control required for producing high-performance materials. They report their findings in a paper in NPG Asia Materials.
The straightforward nature of preparing polymer gels makes them attractive for numerous applications. However, controlling reactions so that all of the polymer molecules grow to the same length and then cross-link in a regular fashion can be challenging. This can lead to the formation of inconsistencies in the polymer structure and the occurrence of short-chain branching during the assembly of the monomers, both of which can result in low-quality materials.
"We have demonstrated a system that uses differences in reaction kinetics to create highly consistent materials," says corresponding author Yukikazu Takeoka. "Using a single catalyst that allows chain growth to proceed before cross-linking begins, we have been able to create networks comprised of polymers with narrow molecular weight distributions, simply by mixing the required reagents."
Balancing the rapid polymerization of a chosen monomer with a sufficiently slow cross-linking process resulted in a spontaneous reaction that gave rise to a regular homogeneous matrix. The stable gel was shown to exhibit responsive properties controlled by both temperature and solvent composition.
"Narrowing the molecular weight distribution of polymers in a gel network leads to a more consistent, higher-performing material," explains lead author Yuto Jochi. "It is our hope that we can further refine our reaction conditions to tailor both polymer molecular weight and stoichiometry of cross-linking to produce completely homogenous networks that can be used in a variety of applications, such as drug delivery and lenses."
This spontaneous synthesis route is able to produce polymer gel matrices with the necessary homogeneity and quality to be used in applications requiring properties such as molecular sieving, high mechanical strength, transparency, stimuli responsiveness and biocompatibility.
This story is adapted from material from Nagoya University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.