On Demand Light‐Degradable Polymers Based on 9,10‐Dialkoxyanthracenes

Light induced degradation of polymers has drawn increasing interest due to the need for externally controllable modulation of materials properties. However, the portfolio of polymers, that undergo precisely controllable degradation, is limited and typically requires UV light. A novel class of backbonedegradable polymers that undergo aerobic degradation in the presence of visible light, yet remain stable against broad-spectrum light under anaerobic conditions is reported. In this design, the polymer backbone is comprised of 9,10-dialkoxyanthracene units that are selectively cleaved by singlet oxygen in the presence of green light as confirmed by NMR and UV/vis spectroscopy. The resulting polymers have been processed by electrohydrodynamic (EHD) co-jetting into bicompartmental microfibers, where one hemisphere is selectively degraded on demand

On Demand Light‐Degradable Polymers Based on 9,10‐Dialkoxyanthracenes

Light induced degradation of polymers has drawn increasing interest due to the need for externally controllable modulation of materials properties. However, the portfolio of polymers, that undergo precisely controllable degradation, is limited and typically requires UV light. A novel class of backbone‐degradable polymers that undergo aerobic degradation in the presence of visible light, yet remain stable against broad‐spectrum light under anaerobic conditions is reported. In this design, the polymer backbone is comprised of 9,10‐dialkoxyanthracene units that are selectively cleaved by singlet oxygen in the presence of green light as confirmed by NMR and UV/vis spectroscopy. The resulting polymers have been processed by electrohydrodynamic (EHD) co‐jetting into bicompartmental microfibers, where one hemisphere is selectively degraded on demand.Light stability and the possibility of degradation in the presence of singlet oxygen and visible light is realized by a novel class of backbone‐degradable polymers containing 9,10‐dialkoxyanthracene units in the polymer backbone. The degradation can be observed with confocal microscopy on fibers fabricated from this polymer and is confirmed by NMR and UV/vis spectroscopy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156157/3/marc202000314-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156157/2/marc202000314.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156157/1/marc202000314_am.pd

Directed Particle Transport via Reconfigurable Fiber Networks

Mass transport limitations of particulates within conventional microanalytical systems are often cited as the root cause for low sensitivity but can be overcome by directed analyte transport, such as via biomolecular motors or gradient surfaces. An ongoing challenge is the development of materials that are passive in nature (i.e., no external power source required), but can reconfigure to perform work, such as transporting particle‐based analytes. Mimicking biology’s concepts of autonomous and reconfigurable materials systems, like the Drosera capensis leaf, reconfigurable fiber networks that effectively concentrate particulates within a localized spot that can act as a detection patch are developed. These networks, prepared by electrohydrodynamic co‐jetting, draw their reconfigurability from a bicompartmental fiber architecture. Upon exposure to neutral pH, a differential swelling of both fiber compartments gives rise to interfacial tension and ultimately results in shape reconfiguration of the fiber network. Compared to free particles, the reconfigurable fiber networks display a 57‐fold increase in analyte detectability, average transport efficiencies of 91.9 ± 2.4%, and separation selectivity between different surface properties of 95 ± 3%. The integration of biomimetic materials into microanalytical systems, exemplified in this study, offers ample opportunities to design novel and effective detection schemes that circumvent mass transport limitations.Biomimetic hydrogel fibers deposited in a structured spiderweb network via electrohydrodynamic co‐jet writing allow for precise control over the direction of their bending motion. The shape reconfigurable network exhibits high selectivity and efficiency in actively transporting particulates. Based on these results, their potential in overcoming mass transport limitations in microanalytical systems is demonstrated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/174803/1/adfm202204080-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/174803/2/adfm202204080_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/174803/3/adfm202204080.pd

Cooperative Switching in Large‐Area Assemblies of Magnetic Janus Particles

Magnetic Janus particles (MJPs) have received considerable attention for their rich assembly behavior and their potential technological role in applications ranging from simple magnetophoretic displays to smart cloaking devices. However, further progress is hampered by the lack of predictive understanding of the cooperative self‐assembly behavior of MJPs and appropriate dynamic control mechanisms. In this paper, a detailed experimental and theoretical investigation into the magnetically directed spatiotemporal self‐assembly and switching of MJPs is presented. For this purpose, a novel type of MJPs with defined hemispherical compartments carrying superparamagnetic iron oxide nanoparticles as well as a novel simulation model to describe their cooperative switching behavior is established. Combination of the theoretical and experimental work culminates in a simple method to direct assemblies of MJPs, even at high particle concentrations. In addition, a magnetophoretic display with switchable MJPs is developed on the basis of the theoretical findings to demonstrate the potential usefulness of controlled large‐area assemblies of magnetic Janus particles.Anisotropic particles that have one hemisphere selectively loaded with magnetite nanoparticles rotate in response to magnetic fields as indicated by visually observable color changes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155896/1/adfm201907865-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155896/2/adfm201907865.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155896/3/adfm201907865_am.pd