Highlight
New Chemical Design Philosophy
Reaction schema
Achievement/Results
Professor Jeffrey Koberstein and his team at Columbia University, through funding provided by the National Science Foundation’s Integrative Graduate Education and Research Traineeship (NSF-IGERT) grant, have demonstrated and begun to characterize a chemical design philosophy whose range of applications in coatings and macromolecule processing will allow applications that have been hitherto unattainable.
The overall schema of the chemicals, shown in I) in the Figure, consists of a bi-functional molecular bridge with photoactive groups at either end that covalently bond with the macromolecule’s backbone. An optional sidechain can be used for everything from increased solubility to the attachment of antibodies.
These chemicals, designed and synthesized through the support of the NSF-IGERT program, have already demonstrated utility and advancements in the polymer processing, polymer coatings, and polymeric hydrogel fields. They can be used to reduce the environmental and health impact of polymeric processing by reducing solvent and additive requirements, eliminating the dangers of monomer contamination such as the bis-phenol A in polycarbonate water bottles. They can be used to prevent dewetting in protective thin films under high temperature conditions (II)), allowing polymeric protective coatings to be used in applications above the polymer’s glass transition, when the coating usually separates from the substrate. And they can be used to create biomedical hydrogels without the additives or monomers that can lead to toxicity and with optional growth factors or antibodies attached to the network (III)).
These chemicals can also crosslink polymers in the solvent-free glassy state, something previously only achieved through ion or electron beam technologies. The potential of this technology is enormous: a small class of molecules with the ability to crosslink and add functionality to broad classes of polymers. Each molecule has been demonstrated to work on multiple polymers without modification. For example, one of the chemicals currently under investigation works on polystyrene, poly(n-butyl-acrylate), poly(tert-butyl-acrylate), poly(n-isopropylacrylamide), polybutadiene and poly(hydroxyethylmethacrylate). These molecules, which already have multiple uses and wide applicability, can also be modified with optional side chains and functionalities that further increase their versatility.
This simple, inexpensive, and powerful chemistry for industrial and consumer polymer applications has wide potential use. One of the specific molecules currently under investigation, bis-benzophenone (bis-BP), has been designed to react in the presence of ultraviolet light, allowing safe and rapid processing. It also requires no solvent to react, allowing less toxic processing and eliminating the danger of solvent leaching in the finished product. It reacts with premade commodity polymers, eliminating the environmental and health dangers of unreacted monomer in the finished product. It is a significant improvement over other techniques that require “cocktails” of chemicals to facilitate crosslinking because it is also the only additive required. The ease of processing, safety, and robustness of this molecule allows it to also be used in protective coatings. Many protective coatings fail at high temperatures because they bead up at high temperatures due to surface tension. This is prevented after the use of this molecule, as shown in II) in the Figure. Parts A) and C) of II) show thin films of polystyrene with bis-BP which are largely intact, while B) and D) show thin films of only polystyrene in which the coating has beaded up and is therefore useless. This opens up applications in aerospace, industry, and commercial products.
The molecular schema has already shown results in polymer processing and thin films; it has further application in the wound healing and surgical fields through hydrogel technology. Hydrogels are macromolecular gels that swell to many times their original size in the presence of water. They are currently being used in the medical field in bandages, and are the subject of extensive and rapid innovation within the biomedical field. Current active research involves adding functionality to hydrogels. This functionality includes the addition of growth hormones, antibodies, and other biological moieties that would improve wound healing rates, drug targeting, antibacterial efficacy, and many others. Polyhydroxyethylmethacrylate, hydrogels of which have been made with bis-BP as shown in III), is one of the polymers being extensively studied by biomedical researchers, and the flexibility of the schema developed by Professor Koberstein and his collaborators allows the simple addition of growth factors, antibodies, or other beneficial moieties to the wound filling hydrogels through the optional side chain shown in I). The addition of factors to the bis-BP is chemically simple and does not interfere with the crosslinking functionality, allowing the creation of functionalized pHEMA hydrogels from commodity pHEMA with no potentially toxic monomer.
Professor Koberstein, his group at Columbia University in the City of New York, his multi-disciplinary and multi-departmental collaborators at Columbia University and beyond have, through funding by the NSF-IGERT, developed a flexible schema for crosslinking macromolecules through molecular bridging that is already being studied for wide-ranging applications including healthy and environmentally safe macromolecule processing, high performance coatings, and wound filling and wound healing materials.
Address Goals
The achievements of Professor Koberstein and his group, as described in the above highlights sections, address the numerous strategic goals of the National Science Foundation’s Integrative Graduate Education and Research Traineeship (MSF-IGERT) and, more specifically, the primary and secondary goals of Discovery and Learning. To better build a scientifically competitive nation, the NSF created the IGERT program to train the next generation of students for the research challenges of tomorrow.
The primary goal is that of Discovery: To foster research that will advance the frontiers of knowledge, emphasizing areas of greatest opportunity and potential benefit and establishing the Nation as a global leaser in fundamental transformational science and engineering. The above described work by fulfills this goal through wide applicability, improved environmental and human health, and easily applied chemistry. A small fraction of the range of applications for this new chemistry has already been discussed above and includes environmentally safer solvent-free polymer processing, polymer thin films, and biomedical applications in wound healing, hydrogels, and drug delivery. The wide range of applications offers almost limitless opportunity and potential benefit at little cost, which would put the Nation on the forefront of new applications that have yet to be developed. This is research into a powerful new tool that provides enormous practical opportunities and significant practical potential. The research allows the Nation to be on the forefront of an emerging macromolecular technology. This is transformative science and engineering at its heart.
This work has already been presented in four national meetings, including those of the American Physical Society and American Chemical Society. It has also been the subject of two papers in peer-reviewed scientific journals. It will be presented at this year’s Gordon Conference on Surfaces and Adhesion and two more papers are being written at this time. These papers and presentations have been authored and presented by both graduate students and undergraduates of multiple nationalities, ethnicities, and departments. This is part of how the work has fulfilled the secondary goal of the NSF-IGERT program: Learning. The Learning strategic goal is to cultivate a world-class, broadly inclusive science and engineering workforce and expand the scientific literacy of all citizens. The work on this project has been performed by three graduate students and over five undergraduates from chemistry, chemical engineering, and biomedical backgrounds. This has fostered learning in each of them, and they have each presented their work to their peers in a multidisciplinary setting, further improving their scientific acumen and ability to communicate their work to others. They are a multi-ethnic, multi-departmental, and multi-nationality group whose interactions help foster broadly inclusive science and engineering. Professor Koberstein’s group and collaborators also bring their knowledge and experience to all citizens through tutoring, teaching weekend science at local high schools, and presentations and tours of the lab for high schools students. This helps expose all citizens to the potentials and realities of scientific research and expands citizens’ scientific literacy. This fulfills the secondary strategic goal of Learning.
Professor Koberstein, his group at Columbia University, and his multi-disciplinary and multi-departmental collaborators at Columbia University and beyond have, through funding by the National Science Foundation’s Integrative Graduate Education and Research Traineeship, demonstrated the NSF strategic goals of Discovery and Learning through the wide applicability and utility of their research and extensive community outreach through tutoring, teaching, and presentations and tours of the lab.
