RAFT polymerization allows the synthesis of well-defined (co)polymer architectures comprising primary benzene sulfonamide groups, either using an acrylamido sulfonamide monomer or a sulfonamide-functional trithiocarbonate RAFT agent. This work unlocks the potential for accessing a new generation of pH-responsive block copolymers and functional polymeric vectors with targeting properties for biomedical applications.
Fan-out wafer-level packaging (FOWLP) urgently demands low dielectric constant and dissipation factor interlayer dielectric materials to mitigate high transmission loss at high frequencies. Polyimides (PIs) are widely used as interlayer dielectric materials in FOWLP due to their excellent comprehensive properties. However, addressing the challenge of decreasing the dielectric constant and dissipation factor of PIs at high frequencies to meet the application requirements remains an active pursuit in both industry and academia. In this study, we designed and synthesized a novel diamine monomer featuring bis(trifluoromethyl) pendant groups, denoted as 4,4′-((3′,5′-bis(trifluoromethyl)-[1,1′-biphenyl]-3,5-diyl)bis(oxy))dianiline (HFBODA). The binary polymerization of this diamine monomer with common dianhydrides led to promising outcomes. Remarkably, among the prepared PIs, 6FDA-HFBODA exhibited excellent properties (Td,5% = 521 °C, Tg = 240 °C, Dk = 2.63 and Df = 3.72 × 10−3) at 10 GHz. Additionally, BPADA-HFBODA demonstrated an ultra-low Df value of 2.30 × 10−3 at 10 GHz. The relationship between the charge density of imide in PIs and the dissipation factor of PIs was investigated for the first time. By introducing strong electron-withdrawing groups to the side group of PI, the effect of the imide ring on the orientation polarization was greatly declined; thus, the dissipation factor of PI at high frequency was significantly decreased. Besides, the relationship between the structures and other essential properties of PIs in this study was systematically explored. This work provides a novel diamine and demonstrates the role of trifluoromethyl located in the side group in lowering the dissipation factors of PIs at high frequencies. The introduction of a bis(trifluoromethyl) pendant group led to a reduction in polarizability and an increase in free volume within the PIs. Moreover, the electron-withdrawing effect of the trifluoromethyl group substantially minimized the probability of internal friction among dipoles, resulting in reduced dielectric constants and dissipation factors. These findings provide crucial insights and guidance for the future design and research of low dielectric constant and dissipation factor PIs, particularly for high-frequency applications in fan-out wafer-level packaging.
Xanthene-modified 1,2-dioxetane (Xa-Ad) derivatives were designed and synthesized using a facile protocol, and their mechanical activity was identified for the first time to the best of our knowledge. When these derivatives were incorporated into polymer main chains or crosslinked networks, the resultant polymers were mechanochemiluminescent (MCL). Bright chemiluminescence was observed when stretching the bulk polymer. Xa-Ad, as a new MCL mechanophore, was found according to DFT simulations and experimental results to exhibit a force threshold lower than that of bis(adamantyl) dioxetane, the only chemiluminescent mechanophore reported so far. The current study has not only increased the structural diversity of MCL mechanophores, but has also offered an efficient way to modulate the corresponding mechanochemical activity.
The transition to sustainable routes boosts the growth of academic research focused on replacements for isocyanate-based polyurethanes (PUs). Non-isocyanate polyurethanes (NIPUs) produced by aminolysis of cyclic carbonates are treated as promising replacements for PUs. Herein, we report a novel cross-linked NIPU material prepared from resveratrol and CO2. The rigid conjugated structure of resveratrol gives NIPUs excellent mechanical properties, with the capacity to produce robust materials with tensile stresses reaching 92 MPa. In addition, functional pre-monomers can be obtained by alcoholysis of cross-linked NIPUs, and bio-based cyclic carbonates can be regenerated by a ring-closing reaction. The regenerated bio-based cyclic carbonates remain as monomers with the same reactive efficiency, and the re-prepared NIPUs exhibit the same structures and properties. This work investigates an ecologically friendly synthetic pathway for the production of high-performance and chemically recyclable cross-linked NIPU materials using renewable resources, which will enrich the synthetic strategy and recycling of NIPU-based chemistry.
Polymer architecture can influence the morphology of polymer self-assemblies. However, although the ability to control the nanostructure of self-assemblies is crucial for optimizing their potential applications, the ways in which changes in macromolecular architecture affect the structures of self-assemblies and the conformation of polymer chains in self-assemblies remain virtually unknown. Herein, we investigate the self-assembly behavior of four amphiphilic copolymers with different chain configurations, namely, AB, ABA, 3-arm block copolymers, and cyclic graft copolymers. We demonstrate that changes in the macromolecular architecture can result in the formation of different nanostructures, including unilamellar vesicles, cylindrical micelles, spherical micelles, and multilamellar vesicles. X-ray and light-scattering measurements also reveal that the conformations of the polymer chains in the self-assemblies are different, which contributes to the differences in their nanostructures. Our findings provide insights into the ways in which changes in polymer architecture affect self-assembly behavior and suggest that the macromolecular architecture should be considered an important factor for controlling the structure of molecular assemblies.
Ring-opening copolymerization is an important means to combine the properties of two or more monomers and fine-tune the properties of polymers. The copolymerization of two different types of monomers with full recyclability, however, has been rare. Here, we copolymerized the rigid 4-hydroxyproline-derived thiolactone with various lipoic acid derivatives that have flexible backbones to prepare poly(thioester-co-disulfide) copolymers with tunable thermal and mechanical properties. Owing to the full recyclability of both types of monomers, the resulting copolymers can be completely depolymerized to recycle both monomers in high monomer yields. This work provides a detailed understanding regarding the kinetics and controllability of the copolymerization system of thiolactone and 1,2-dithiolane, which may facilitate the design, modification, and strengthening of new recyclable polymer materials in the future.
The introduction of thioester linkages into the backbone of free-radical polymerization-produced polymers has received recently renewed interest due to their use in preparing (bio)degradable polymers. To access monomers capable of introducing the thioester functionality, a novel monothiolated analogue of the cyclic ketene acetal (CKA) class of radical ring-opening polymerization (rROP) monomers was synthesized and examined, specifically O,S-BMDO. Interestingly, O,S-BMDO offers an example of an orthogonal rROP monomer, being capable of introducing thioesters, thionoesters, or a mixture of both functional groups into the polymer backbone, with the ratio of these functional groups affected by the comonomer and the reaction conditions. This unusual effect was explored both experimentally and computationally. This report constitutes the first time a thionoester-containing repeating unit has been introduced directly by radical polymerization. In addition, the polymerization of O,S-BMDO can produce a rare poly(thionoester) homopolymer.
Although the common data-driven studies for material development use property values present in the database, the effectiveness of analysing and exploring the areas without property values in the database has hardly been clarified. The necessity to analyse such areas is evident from the fact that only 44% of polymer chemical structure entries with property values are used for studies, while the remaining 56% are not in the analysis of glass transition temperatures using the PoLyInfo database. In this study, a method for discovering polymer materials with undiscovered properties was demonstrated and experimentally verified. The study utilised a comprehensive database of polymer materials and properties with an exceptional search procedure that defines unexplored areas in the database. In addition, a filter based on the physicochemical mechanism of polymers was used to remove the common molecular structures to reveal polymers with contradictory properties. Similarly, a mechanism-based filter was also used to narrow down the candidates efficiently. We investigated a practically challenging heat-resistant transparent polymer material with this procedure and experimentally verified the screening candidate obtained by molecular dynamic simulations and machine-learning predictions. Consequently, potential polymer materials were discovered with thermal degradation temperature, Tdeg, higher than 300 °C without glass transition in the entire temperature range, and high transparency (more than 80% transmittance) in the visible and UV regions.
Herein, inspired by the structure of phosphatidylcholine lipid (a typical cartilage matrix) with the presence of zwitterionic charges, a bottlebrush polymer was developed, namely poly(4-(methyl)propenamidophenylboronic acid)-co-poly(methyl methacrylate)-b-((poly(2-(2-bromoisobutyryloxy)ethyl methacrylate)-co-poly(methyl methacrylate))-g-poly-(2-methacryloyloxyethyl phosphorylcholine)) via atom transfer radical polymerization (ATRP) and reversible addition–fragmentation chain-transfer radical polymerization (RAFT). The biomimetic bottlebrush included two main regions responsible for lubrication and drug loading. The brush zone could enhance the lubrication due to the formation of a tenacious hydration layer surrounding the zwitterionic charges of poly(2-methacryloyloxyethyl phosphorylcholine) brush polymer (PMPC), while the anchoring zone was responsible for the local delivery of curcumin as an anti-inflammatory drug. The synthesized bottlebrush polymer with integrated features of both enhanced lubrication and sustained drug delivery can be an efficient intra-articular nanomedicine for the treatment of osteoarthritis.
Photobase generators (PBGs) are an attractive tool for the latent and spatially governed formation of polymer networks with uniform topologies due to the anionic step-growth mechanistic pathway they unlock. Despite the significant advances made in PBG frameworks, utility in rapid, visible light driven polymer formation and associated structure–reactivity relationships remain scarce. Herein, five coumarinylmethyl PBGs bearing caged tetramethylguanidine (TMG) were synthesized and systematically examined for inducing thiol–ene polymerizations, while benchmarking against the classic ortho-nitrobenzyl (oNB) PBG framework. Quantification of photopolymerization kinetics and bond scission quantum yields with real-time Fourier transform infrared and steady-state UV-vis absorption spectroscopies revealed an increase in the disparity between CC and S–H conversion for derivatives halogenated at the 3-position. Alternatively, incorporation of a π-extended styryl moiety at the same position decreased the conversion gap and enabled uncaging with a blue LED (470 nm). This gap was attributed to the concurrent activation of radical chain-growth and base-catalyzed step-growth mechanisms, which was tempered through the (sub-)stoichiometric addition of tetramethylpiperidinyloxy (TEMPO). These findings paint a detailed picture of PBGs for thiol–ene polymerizations that will inform the selection and optimization of future light-activated catalysts and enable advanced manufacturing of tailored soft materials.
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