Advanced synthetic materials are needed to produce nano‐ and mesoscale structures that function autonomously, catalyze reactions, and convert chemical energy into motion. This paper describes supracolloidal fiber‐like structures that are composed of self‐adhering, or “sticky,” oil‐in‐water emulsion droplets. Polymer zwitterion surfactants serve as the key interfacial components of these materials, enabling multiple functions simultaneously, including acting as droplet‐stabilizing surfactants, interdroplet adhesives, and building blocks of the fibers. This fiber motion, a surprising additional feature of these supracolloidal structures, is observed at the air–water interface and hinged on the chemistry of the polymer surfactant. The origin of this motion is hypothesized to involve transport of polymer from the oil–water interface to the air–water interface, which generates a Marangoni (interfacial) stress. Harnessing this fiber motion with functional polymer surfactants, and selection of the oil phase, produced worm‐like objects capable of rotation, oscillation, and/or response to external fields. Overall, these supracolloidal fibers fill a design gap between self‐propelled nano/microscale particles and macroscale motors, and have the potential to serve as new components of soft, responsive materials structures.
Bicontinuous cubic (Q) lyotropic liquid crystal (LLC)‐derived polymer networks possess periodic, uniform‐size, 3D‐interconnected nanopores that make them highly desirable organic materials for selective molecular separation and uptake applications. To date, there are no reported examples of a Q‐phase network with additional functional properties, such as catalytic reactivity, response to external stimuli, or gated transport, that would expand the usefulness of this class of porous materials. Here, a functionalized gyroid‐type Q polymer network material that can be used for potential gated transport or adaptive uptake applications is presented. This material contains a novel spiropyran‐containing dopant monomer that upon blending and cross‐linking with a gyroid‐forming LLC monomer, yields a gyroid polymer material that retains its phase architecture while reversibly responding to changes in external solution and vapor pH. Studies also demonstrate that this system is capable of strongly binding to aq. Pb2+ions when activated by UV light, allowing it to function as a potential colorimetric sorbent or gated‐response material.
more » « less- Award ID(s):
- 1720530
- PAR ID:
- 10442901
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 10
- Issue:
- 5
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract Smart materials with coupled optical and mechanical responsiveness to external stimuli, as inspired by nature, are of interest for the biomimetic design of the next generation of soft machines and wearable electronics. A tough polymer that shows adaptable and switchable mechanical and fluorescent properties is designed using a fluorescent lanthanide, europium (Eu). The dynamic Eu‐iminodiacetate (IDA) coordination is incorporated to build up the physical cross‐linking network in the polymer film consisting of two interpenetrated networks. Reversible disruption and reformation of Eu‐IDA complexation endow high stiffness, toughness, and stretchability to the polymer elastomer through energy dissipation of dynamic coordination. Water that binds to Eu3+ions shows an interesting impact simultaneously on the mechanical strength and fluorescent emission of the Eu‐containing polymer elastomer. The mechanical states of the polymer, along with the visually optical response through the emission color change of the polymer film, are reversibly switchable with moisture as a stimulus. The coupled response in the mechanical strength and emissive color in one single material is potentially applicable for smart materials requiring an optical readout of their mechanical properties.
-
more » « less
Abstract Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre‐irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu24L24metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between CuII, CuI, and Cu0. The instability of the MOC junctions in the CuIand Cu0states leads to network disassembly, forming CuI/Cu0solutions, respectively, that are stable until re‐oxidation to CuIIand supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks.
-
more » « less
Abstract Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre‐irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu24L24metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between CuII, CuI, and Cu0. The instability of the MOC junctions in the CuIand Cu0states leads to network disassembly, forming CuI/Cu0solutions, respectively, that are stable until re‐oxidation to CuIIand supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks.
-
more » « less
Abstract Neither of us can remember people talking about stimuli‐responsive polymers when we were students. Even though this was still in the last century, it was almost 70 years after Staudinger's seminal paper “Über Polymerisation”![1]By the time we entered graduate school in the early 1990 s, the first papers on polymer light emitting diodes appeared, while research on electrically conducting, nonlinear optical, and other “functional” polymers was already in full swing. Looking back, there were some stimuli‐responsive materials that were around at the time,[2–6]but it took the better part of the last 30 years until the field had developed into what we think is one of the most vibrant areas of polymer science.[8–12]Before the potential usefulness of this class of materials was recognized, researchers were focused on developing polymeric materials that would not respond to external influences, and in fact maintain (in particular) their mechanical properties in a wide range of environments. This has led to the development of many environmentally robust polymers, which have come to impact basically every aspect of our daily life. Ironically, this long‐sought stability now comes back to haunt us in the form of plastic pollution, but this is another story. The concept of materials that adapt their properties in response to changing environmental conditions might appear like a complete reversal with respect to the original goals of creating stable materials. However, eventually a) it was recognized that materials that respond to a specific stimulus in a predictable and useful manner would significantly broaden the potential usefulness of polymers, and b) the field of polymer science had developed to the point where the rational design, preparation, and characterization of such materials became possible. The expression
‘stimuli‐responsive polymer ’ had been first used in the 1980’s, however its use really only gained popularity a few decades later. In the early days, terms such asenvironmentally‐sensitive orenvironmentally‐responsive polymers ,stimuli‐reversible orstimuli‐sensitive polymers , orpolymers with phase transitions have also been used.
