32620-90-9Relevant articles and documents
A Mechanochemical Reaction Cascade for Controlling Load-Strengthening of a Mechanochromic Polymer
Boulatov, Roman,Pan, Yifei,Tian, Yancong,Wang, Chenxu,Weng, Wengui,Xiang, Shishuai,Xu, Piaoxue,Zhang, Huan
, p. 21980 - 21985 (2020)
We demonstrate an intermolecular reaction cascade to control the force which triggers crosslinking of a mechanochromic polymer of spirothiopyran (STP). Mechanochromism arises from rapid reversible force-sensitive isomerization of STP to a merocyanine, which reacts rapidly with activated C=C bonds. The concentration of such bonds, and hence the crosslinking rate, is controlled by force-dependent dissociation of a Diels–Alder adduct of anthracene and maleimide. Because the adduct requires ca. 1 nN higher force to dissociate at the same rate as that of STP isomerization, the cascade limits crosslinking to overstressed regions of the material, which are at the highest rate of material damage. Using comb polymers decreased the minimum concentration of mechanophores required to crosslinking by about 100-fold compared to previous examples of load-strengthening materials. The approach described has potential for controlling a broad range of reaction sequences triggered by mechanical load.
Bridging from the Sequence to Architecture: Graft Copolymers Engineering via Successive Latent Monomer and Grafting-from Strategies?
Zhang, Yajie,Cao, Xiaohuan,Gao, Yang,Xie, Yujie,Huang, Zhihao,Zhang, Zhengbiao,Zhu, Xiulin
, p. 1273 - 1280 (2021)
The on-demand building copolymer structures, from sequence to architecture, is crucial in understanding the relation between polymer structure and property, meanwhile motivating the innovation of polymer hierarchy. However, the challenge is conspicuous for complicated polymer structures from inherently intricate polymerization. In this work, copolymers with tailored grafting density and distributions were achieved using successive latent monomer and grafting-from strategies. The hydroxyl group functionalized furan/maleimide adduct (FMOH) was selected as the latent monomer for RAFT polymerization of an array of copolymers with tailored localization of hydroxyl group along the main chain. The hydroxyl group further initiated the ring opening polymerization (ROP) of L-lactide or ε-caprolactone, resulting in a library of multicomponent copolymers via grafting-from strategy. The initiating efficiency reached to ~100% with variable molecular weight (21300—58600 Da) and narrow distributions (DM 1.25), indicating that such graft copolymers possessed controlled density and distribution of side chains as its linear template. The investigation on thermal properties of the well-defined graft copolymers implied that the precise tailoring over copolymer structures at the molecule level could lead to tunable chemical/physical properties. This work bridged polymer from sequence to architecture, unveiled a new method in creating graft copolymers with programmable structures and provided the insight into the structure/property relationship.
Nucleus-Targeted Organoiridium–Albumin Conjugate for Photodynamic Cancer Therapy
Zhang, Pingyu,Huang, Huaiyi,Banerjee, Samya,Clarkson, Guy J.,Ge, Chen,Imberti, Cinzia,Sadler, Peter J.
, p. 2350 - 2354 (2019)
An organoiridium–albumin bioconjugate (Ir1-HSA) was synthesized by reaction of a pendant maleimide ligand with human serum albumin. The phosphorescence of Ir1-HSA was enhanced significantly compared to parent complex Ir1. The long phosphorescence lifetime and high 1O2 quantum yield of Ir1-HSA are highly favorable properties for photodynamic therapy. Ir1-HSA mainly accumulated in the nucleus of living cancer cells and showed remarkable photocytotoxicity against a range of cancer cell lines and tumor spheroids (light IC50; 0.8–5 μm, photo-cytotoxicity index PI=40–60), while remaining non-toxic to normal cells and normal cell spheroids, even after photo-irradiation. This nucleus-targeting organoiridium-albumin is a strong candidate photosensitizer for anticancer photodynamic therapy.
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.
, (2019/11/13)
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.
