Photo‐Reversible Supramolecular Hydrogels Assembled by α‐Cyclodextrin and Azobenzene Substituted Poly(acrylic acid)s: Effect of Substitution Degree, Concentration, and Tethered Chain Length

Wang, Mingwei; Zhang, Xiaojun; Li, Li; Wang, Junyou; Wang, Jie; Ma, Jun; Yuan, Zhenyu; Lincoln, Stephen F.; Guo, Xuhong

doi:10.1002/mame.201500295

Cited by 25 publications

(14 citation statements)

References 40 publications

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“…For example, in systems where both azobenzene and α-CD are incorporated into polymer chains, the binding constant decreases from 2000 M –1 to 35 M –1 for α-CD- trans -azobenzene and α-CD- cis -azobenzene, respectively, 50 though the exact binding constants can vary based on the chemical details. 51 Additionally, isomerization is reversible by illumination with visible light ( Figure 1 A, red dashed curve), allowing for the formation and destruction of supramolecular complexes on demand.…”

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confidence: 99%

Reconfiguring Gaussian Curvature of Hydrogel Sheets with Photoswitchable Host–Guest Interactions

et al. 2020

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Photoinduced shape morphing has implications in fields ranging from soft robotics to biomedical devices. Despite considerable effort in this area, it remains a challenge to design materials that can be both rapidly deployed and reconfigured into multiple different three-dimensional forms, particularly in aqueous environments. In this work, we present a simple method to program and rewrite spatial variations in swelling and, therefore, Gaussian curvature in thin sheets of hydrogels using photoswitchable supramolecular complexation of azobenzene pendent groups with dissolved α-cyclodextrin. We show that the extent of swelling can be programmed via the proportion of azobenzene isomers, with a 60% decrease in areal swelling from the all trans to the predominantly cis state near room temperature. The use of thin gel sheets provides fast response times in the range of a few tens of seconds, while the shape change is persistent in the absence of light thanks to the slow rate of thermal cis–trans isomerization. Finally, we demonstrate that a single gel sheet can be programmed with a first swelling pattern via spatially defined illumination with ultraviolet light, then erased with white light, and finally redeployed with a different swelling pattern.

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confidence: 99%

Reconfiguring Gaussian Curvature of Hydrogel Sheets with Photoswitchable Host–Guest Interactions

et al. 2020

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“…The differences between the absorption spectra were identified as providing evidence of the isomerization reaction [29]. Thus, UV-vis spectra can be compared more generally as solution or hydrogel chemistries change, to confirm structural changes of the relevant molecules [29,32].…”

Section: Absorption Spectroscopymentioning

confidence: 99%

Advanced Methods for the Characterization of Supramolecular Hydrogels

Denzer

Kulchar

Huang

et al. 2021

Gels

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With the increased research on supramolecular hydrogels, many spectroscopic, diffraction, microscopic, and rheological techniques have been employed to better understand and characterize the material properties of these hydrogels. Specifically, spectroscopic methods are used to characterize the structure of supramolecular hydrogels on the atomic and molecular scales. Diffraction techniques rely on measurements of crystallinity and help in analyzing the structure of supramolecular hydrogels, whereas microscopy allows researchers to inspect these hydrogels at high resolution and acquire a deeper understanding of the morphology and structure of the materials. Furthermore, mechanical characterization is also important for the application of supramolecular hydrogels in different fields. This can be achieved through atomic force microscopy measurements where a probe interacts with the surface of the material. Additionally, rheological characterization can investigate the stiffness as well as the shear-thinning and self-healing properties of the hydrogels. Further, mechanical and surface characterization can be performed by micro-rheology, dynamic light scattering, and tribology methods, among others. In this review, we highlight state-of-the-art techniques for these different characterization methods, focusing on examples where they have been applied to supramolecular hydrogels, and we also provide future directions for research on the various strategies used to analyze this promising type of material.

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“…[22][23][24] Supramolecular hydrogels with the capability to absorb large amounts of water are made via self-assembly through noncovalent interactions such as hydrogen bonding, π-π stacking, Vander Waals interactions, and coordination bonds. [25][26][27][28] In SP hydrogels based on hydrogen bonding, also, multiple hydrogen bonding motifs, such as UPy group, have been used as physical cross-linking units to form reversible networks. 29,30 However, structural specifications of the UPy carrying synthons greatly influence physical and mechanical properties of the resulting SPs.…”

Section: Among Common Tpes Linear Triblock Copolymers Has Recentlymentioning

confidence: 99%

Impact of supramolecular interactions on swelling and release behavior of UPy functionalized HEMA‐based hydrogels

Maleki

Shokrollahi

Barzin

2018

Polymers for Advanced Techs

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Supramolecular polymeric hydrogels based on copolymers of 2‐hydroxyethyl methacrylate (HEMA) and HEMA functionalized with ureidopyrimidinone (quadruple H‐bonding motifs and HU comonomer) were prepared at different HU comonomer ratios (PH‐Sn, n = HU mol%). For comparison, HEMA homopolymers (PH‐Cn, n = mol% of a chemical cross‐linker) were synthesized. In contrast to PH‐S0, PH‐Sn copolymers act like cross‐linked hydrogels and absorb large amounts of water while retaining shape. Viscosities of the hydrogels decreased, and elastic and loss moduli increased with increasing HU content. Compression modulus of the swollen PH‐Sn hydrogels increased with HU content and varied between 54 and 240 kPa. Study of metronidazole loading/release behaviors of PH‐S6 hydrogel against PH‐C6 revealed a negligible burst effect for the former and a sustained release that continued for about 120 hours. We conclude that modification of poly(2‐hydroxyethyl methacrylate) with HU through urethane linkages is an effective strategy to developing physical hydrogels with predictable behavior for biomedical applications.

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Photo‐Reversible Supramolecular Hydrogels Assembled by α‐Cyclodextrin and Azobenzene Substituted Poly(acrylic acid)s: Effect of Substitution Degree, Concentration, and Tethered Chain Length

Cited by 25 publications

References 40 publications

Reconfiguring Gaussian Curvature of Hydrogel Sheets with Photoswitchable Host–Guest Interactions

Reconfiguring Gaussian Curvature of Hydrogel Sheets with Photoswitchable Host–Guest Interactions

Advanced Methods for the Characterization of Supramolecular Hydrogels

Impact of supramolecular interactions on swelling and release behavior of UPy functionalized HEMA‐based hydrogels

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