Main-chain stimuli-responsive polymers synthesized via polymerization techniques that do not rely on metal-based catalysis are highly desirable for economic reasons and to avoid metal-polymer interactions. Herein, we introduce a metal-free head-to-tail organobase-catalyzed hydroxyl-yne click polymerization of an AB-type monomer to realize photoswitchable polymers featuring α-bismines as main-chain repeating units. The prepared main-chain α-bisimine-based polymers show excellent photoswitching in solution. We further post-functionalize the obtained polymers with various thiol compounds via thiol-Michael reactions to significantly lower the glass transition temperature (), likely to be beneficial for the photoswitching process in the solid state. Thus, the herein introduced polymerization technique not only provides metal-free access to main-chain stimuli-responsive polymers, but also allows for the flexible post-modification of the obtained polymers to generate advanced macromolecular architectures with tunable properties.
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http://dx.doi.org/10.1021/acsmacrolett.4c00216 | DOI Listing |
Angew Chem Int Ed Engl
October 2024
Pritzker School of Molecular Engineering, University of Chicago, IL 60637, Chicago, USA.
The integration of mechanically interlocked molecules (MIMs) into polymeric materials has led to the development of mechanically interlocked polymers (MIPs). One class of MIPs that have gained attention in recent years are slide-ring gels (SRGs), which are generally accessed by crosslinking rings on a main-chain polyrotaxane. The mobility of the interlocked crosslinking moieties along the polymer backbone imparts enhanced properties onto these networks.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Laboratory of Synthesis and Natural Products I, nstitute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH 5304, 1015, Lausanne, Switzerland.
We report in this paper a novel Cu-catalyzed synthesis of polysubstituted 1-pyrrolines. The reaction of β,γ-unsaturated oxime esters 4 with terminal alkynes 5 in the presence of a catalytic amount of Cu(OAc) and 2,2'-biquinoline affords the corresponding 1,6-enynimines, which undergo a highly stereoselective Alder-ene reaction to afford 1-pyrrolines with concomitant generation of a quaternary carbon and a 2-azadiene motif. It represents an unusual [4+1] heteroannulation reaction wherein terminal alkynes act as a one carbon donor and are 1,1-difunctionalized.
View Article and Find Full Text PDFChem Sci
August 2024
School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
The advent of reversible deactivation radical polymerization (RDRP) revolutionized polymer chemistry and paved the way for accessing synthetic polymers with controlled sequences based on vinylic monomers. An inherent limitation of vinylic polymers stems from their all-carbon backbone, which limits both function and degradability. Herein, we report a synthetic strategy utilizing radical ring-opening polymerization (rROP) of complementary photoreactive cyclic monomers in combination with RDRP to embed photoresponsive functionality into desired blocks of polyvinyl polymers.
View Article and Find Full Text PDFChem Sci
July 2024
Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, College of Chemistry, Xiangtan University Xiangtan 411105 P. R. China
Two soluble conjugated ladder polymers (cLPs), decorated with multiple electron-poor species (, cyano groups, fused pentagons, and N-heterocyclic rings), have been synthesized from the newly developed tetraketo-functionalized double aza[5]helicene building blocks using a single-step Knoevenagel polycondensation strategy. This facile approach features mild conditions (, room temperature) and high efficiency, allowing us to quickly access a nonalternant ladder-like conjugated system with the formation of multicyano substituents in the backbone. Analysis by H NMR, FT-Raman, and FT-IR spectra confirms the successful synthesis of the resulting cLPs.
View Article and Find Full Text PDFNat Commun
July 2024
Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-Si, Gyeonggi-do, 17104, South Korea.
Monitoring mechanical stresses in microchannels is challenging. Herein, we report the development of a mechanofluorescence sensor system featuring a fluorogenic single polydiacetylene (PDA) particle, fabricated using a co-flow microfluidic method. We construct a stenotic vessel-mimicking capillary channel, in which the hydrodynamically captured PDA particle is subjected to controlled fluid flows.
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