1585-90-6Relevant articles and documents
Stereochemical effects on the mechanochemical scission of furan-maleimide Diels-Alder adducts
Wang, Zi,Craig, Stephen L.
, p. 12263 - 12266 (2019)
Clarifying the correlation between the chemical structure of mechanophores and their mechanical reactivity informs the design of mechanochemical systems. One specific correlation that has received much recent attention is that between stereoisomerism and mechanical reactivity. Here, we report previously unobserved differences in the mechanical reactivity of furan-maleimide Diels-Alder (DA) stereoisomers. We evaluated the internal competition between the mechanically triggered retro-DA reaction and the mechanochemical ring opening of gem-dichlorocyclopropane mechanophores in the pulsed sonication of polymer solutions. The relative extent of the two sonomechanochemical reactions in the same polymer shows that the endo DA isomer exhibits greater mechanical lability than its exo isomer. This result contrasts with recent measurements of the relative rates of scission in a similar system and points to potential enhanced sensitivity obtained through the use of internal competition as opposed to absolute rates in assessing mechanical reactivity in sonication studies.
Glass-transition temperature governs the thermal decrosslinking behavior of Diels–Alder crosslinked polymethacrylate networks
Dobbins, Daniel J.,Scheutz, Georg M.,Sun, Hao,Crouse, Christopher A.,Sumerlin, Brent S.
, (2019)
A series of Diels–Alder (DA) crosslinked polymethacrylate networks covering a broad range of glass-transition temperatures (Tg) was prepared to establish the relationship between the Tg and the thermal decrosslinking behavior of these networks. A series of permanently crosslinked and uncrosslinked analogues were also prepared to better understand the thermoset-to-thermoplastic transition occurring in the DA networks at elevated temperatures. The network series were studied using dynamic mechanical analysis, which established an inverse relationship between Tg and decrosslinking ability. Differential scanning calorimetry confirmed the viability of the DA linkages in all formulations, and a trapping experiment with 9-anthracenemethanol demonstrated that even the least responsive network was capable of undergoing decrosslinking given appropriate thermal treatment. While polymer chain mobility has long been understood to be a critical factor in healable materials, this work verifies the importance of this parameter in the decrosslinking of DA networks.
Albumin-polymer conjugate nanoparticles and their interactions with prostate cancer cells in 2D and 3D culture: Comparison between PMMA and PCL
Jiang, Yanyan,Lu, Hongxu,Dag, Aydan,Hart-Smith, Gene,Stenzel, Martina H.
, p. 2017 - 2027 (2016)
Using proteins as the hydrophilic moiety can dramatically improve the biodegradability and biocompatibility of self-assembled amphiphilic nanoparticles in the field of nanomedicine. In this study, we fabricated and evaluated curcumin loaded albumin-polycaprolactone nanoparticles as a novel drug delivery system for prostate carcinoma therapeutics and compared their performance to poly(methyl methacrylate) (PMMA), a non-degradable and amorphous polymer. The maleimide functionalized poly(ε-caprolactone) (PCL) was obtain using ring opening polymerization (ROP) of ε-caprolactone where N-(2-hydroxyethyl)maleimide was used as an initiator. The resorbable albumin-polymer conjugate was prepared by conjugating the hydrophobic maleimide-terminated PCL to the hydrophilic bovine serum albumin (BSA) via a simple Michael addition reaction. PMMA was conjugated in a similar manner. The amphiphilic BSA-polymer conjugates can self-assemble into nanoparticles, displaying well-defined structure, prolonged storage stability, and excellent biocompatibility. The BSA nanoparticles, with encapsulated curcumin, exhibited highly enhanced antitumor activity compared to free curcumin. Furthermore, the high efficacy of the curcumin loaded nanoparticles was verified by effectively inhibiting the growth of three-dimensional LNCaP multicellular tumour spheroids. The cytotoxicity was attributed to the efficient cellular uptake of the nanoparticles through caveolic endocytosis. The direct comparison between PCL and the PMMA revealed that drug loading and release as well as cytotoxicity is not significantly affected by the nature of the polymer. However, it seems that nanoparticles based on PMMA penetrate quicker into LNCaP multicellular tumour spheroids thanks to the increased stability. The faster penetration was found to reduce the toxicity of the nanoparticles as evidenced by the lower number of dead cells. In contrast, the fully degradable PCL-based nanoparticles were more efficient in delivering the drug, thus limiting the growth of LNCaP multicellular tumour spheroids.
4D-Printing of Photoswitchable Actuators
Lu, Xili,Ambulo, Cedric P.,Wang, Suitu,Rivera-Tarazona, Laura K.,Kim, Hyun,Searles, Kyle,Ware, Taylor H.
, p. 5536 - 5543 (2021)
Shape-switching behavior, where a transient stimulus induces an indefinitely stable deformation that can be recovered on exposure to another transient stimulus, is critical to building smart structures from responsive polymers as continue power is not needed to maintain deformations. Herein, we 4D-print shape-switching liquid crystalline elastomers (LCEs) functionalized with supramolecular crosslinks, dynamic covalent crosslinks, and azobenzene. The salient property of shape-switching LCEs is that light induces long-lived, deformation that can be recovered on-demand by heating. UV-light isomerizes azobenzene from trans to cis, and temporarily breaks the supramolecular crosslinks, resulting in a programmed deformation. After UV, the shape-switching LCEs fix more than 90 % of the deformation over 3 days by the reformed supramolecular crosslinks. Using the shape-switching properties, we print Braille-like actuators that can be photoswitched to display different letters. This new class of photoswitchable actuators may impact applications such as deployable devices where continuous application of power is impractical.
Efficient method for the synthesis of functionalized basic maleimides
Salewska, Natalia,Milewska, Maria J.
, p. 999 - 1003 (2014)
A three-step procedure involving Diels-Alder condensation of maleic anhydride with furane, formation of N-substituted imide upon reaction with appropriate diamine, and a final retro Diels-Alder regeneration of the maleic carbon-carbon double bond is proposed for an unequivocal synthesis of N-substituted basic maleimides. The novel method is characterized by mild reaction conditions, easy work-up, high yields, and no need for additional catalysis.
Self-healing polyurethanes with shape recovery
Heo, Yunseon,Sodano, Henry A.
, p. 5261 - 5268,8 (2014)
Two new thermoresponsive self-healing polyurethanes (1DA1T and 1.5DA1T) based on the Diels-Alder (DA) reaction between furan and maleimide moieties are developed that use the shape-memory effect to bring crack faces into intimate contact such that healing can take place. Unlike other self-healing polymers, these polymers do not require external forces to close cracks but rather they use the shape-memory effect to autonomously close the crack. Both polyurethanes have a stable polymer structure and comparable mechanical properties to commercial epoxies. A differential scanning calorimeter is employed to check the glass transition temperature of the polymers as well as the DA and retro-DA (rDA) reaction temperatures. These DA and rDA reactions are confirmed with variable-temperature proton nuclear magnetic resonance. Healing efficiency is calculated using a measurement of the failure load from compact tension testing. The results show that the shape-memory effect can replace external forces to close two crack surfaces and the DA reaction can be repeatedly employed to heal the cracks.
Controlled Covalent Functionalization of 2 H-MoS2 with Molecular or Polymeric Adlayers
Quirós-Ovies, Ramiro,Vázquez Sulleiro, Manuel,Vera-Hidalgo, Mariano,Prieto, Javier,Gómez, I. Jénnifer,Sebastián, Víctor,Santamaría, Jesús,Pérez, Emilio M.
supporting information, p. 6629 - 6634 (2020/04/07)
Most air-stable 2D materials are relatively inert, which makes their chemical modification difficult. In particular, in the case of MoS2, the semiconducting 2 H-MoS2 is much less reactive than its metallic counterpart, 1T-MoS2. As a consequence, there are hardly any reliable methods for the covalent modification of 2 H-MoS2. An ideal method for the chemical functionalization of such materials should be both mild, not requiring the introduction of a large number of defects, and versatile, allowing for the decoration with as many different functional groups as possible. Herein, a comprehensive study on the covalent functionalization of 2 H-MoS2 with maleimides is presented. The use of a base (Et3N) leads to the in situ formation of a succinimide polymer layer, covalently connected to MoS2. In contrast, in the absence of base, functionalization stops at the molecular level. Moreover, the functionalization protocol is mild (occurs at room temperature), fast (nearly complete in 1 h), and very flexible (11 different solvents and 10 different maleimides tested). In practical terms, the procedures described here allow for the chemist to manipulate 2 H-MoS2 in a very flexible way, decorating it with polymers or molecules, and with a wide range of functional groups for subsequent modification. Conceptually, the spurious formation of an organic polymer might be general to other methods of functionalization of 2D materials, where a large excess of molecular reagents is typically used.
