Polymer Chemistry最新文献

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Compositional modifications of conducting polymer-based graft copolymers enable precise tuning of their properties, including conductivity, degradation and opto-electrochemical properties. This work investigates how the composition of poly(caprolactone)-graft-oligo(3-hexylthiophene)s, (P(CL-co-AVL)-g-O3HT), previously shown to be degradable, effects the morphological and opto-electrochemical properties of the copolymers. Effect of different grafting density and the length of the O3HT grafts on the material's properties were investigated using a range of advanced techniques, such as, spectroelectrochemistry, cyclic voltammetry, 2D-GIXRD and 4D-STEM. Short O3HT grafts (n = 15) yielded amorphous copolymers, whereas longer grafts (n = 30, 40) produced semi-crystalline material with distinct crystalline and amorphous redox signatures. High grafting density promoted formation of interconnected nanoscale O3HT crystallites. Thermal annealing (40–60 °C) or trace acetonitrile (1 vol%) in casting solutions enhanced intrachain order and crystallization, and, in turn, enhanced optoelectronic properties of the high-density, long grafts copolymers. These findings establish structure–property relationship in conducting polymer-based graft copolymers, guiding their macromolecular design, including for transient electronics.

Polyethylene terephthalate (PET), a dominant polymer in global plastic production, faces critical recycling challenges due to its persistence in ecosystems and limitations of conventional mechanical/thermal recycling. Upcycling PET waste into value-added polymers represents a transformative approach toward a circular plastics economy. This review systematically examines innovative strategies for chemically converting post-consumer PET into novel polymeric materials, thereby bypassing the performance degradation typically associated with traditional recycling. Key pathways include (1) depolymerization into monomers (terephthalic acid, ethylene glycol) for repolymerization into high-purity PET or advanced polyesters (e.g., biodegradable or bio-based variants), (2) transformation into functional polymers such as polyurethanes, epoxy resins, and ion-exchange membranes via tailored catalytic processes, and (3) copolymerization/blending with biopolymers to enhance material properties. Breakthroughs in catalysts (enzymes, ionic liquids), solvent-free systems, and energy-efficient reactors are highlighted for improving the reaction selectivity and scalability. Despite progress, challenges persist in managing mixed plastic wastes, removing contaminants, and achieving cost parity with virgin polymers. Emerging trends, including enzymatic engineering and AI-guided monomer-to-polymer design, are proposed to address these barriers. By bridging molecular innovation with industrial feasibility, PET upcycling offers dual environmental and economic incentives to close the plastic lifecycle loop.

Due to its metal-free polymeric nature, ease of synthesis using low-cost earth-abundant precursors and tunable optoelectronic properties, graphitic carbon nitride (GCN) is extensively used in solar fuel production. Despite two decades of extensive research, the fundamentals of the thermal polymerization process leading to the formation of GCN are inadequately understood. In this work, we employ cyanamide (CYN) and dicyandiamide (DCDA) precursors and systematically reveal the polymerization mechanism. Though CYN has half the amount of C and N compared with DCDA, it yielded virtually similar structural properties and a similar degree of conjugation that determines the energetic difference for π-to-π* fundamental (optical) transitions and photoexcited lifetimes. Detailed complementary analysis using thermal methods, along with quantifying the amount of NH₃ released using the temperature-programmed desorption technique, offered unique insights into the polymerization process. Unlike previous notions, the results unambiguously demonstrate that GCN formation need not always release NH₃ as a result of a thermal condensation reaction. Rather, it is possible that molecular rearrangement (dimerization and/or cyclization) of intermediate condensates can also play a major role in the formation of melamine, which is found to be an important intermediate. The obtained mechanistic insights into the thermodynamics of the polymerization process and its impact on optoelectronic properties and photoelectrochemical performance will aid the rational design of GCN to enhance the efficiency of solar energy conversion.

Herein, we introduce the synthesis of fully renewable and extrudable high oleic sunflower oil-based acetal containing covalent adaptable networks (CANs) via a catalyst and solvent-free click-like reaction between a bio-based polyol and divinyl ether, i.e. 1,4-cyclohexanedimethanol divinyl ether. High oleic sunflower oil was therefore first converted into the respective polyol via a simple H₂SO₄ catalyzed Friedel–Crafts alkylation using catechol within 30 minutes at 120 °C. After subsequent structural characterization of the polyol, acetal containing CANs showing high cross-linking densities, fast stress relaxation, and excellent malleability were synthesized without releasing any small-molecule byproducts. The presence of the catechol moiety is particularly interesting, as the presence of an adjacent phenolic group induces neighboring group participation effects and accelerates exchange reaction rates. The dynamic behavior of the new cross-linked materials was confirmed by stress relaxation measurements at different temperatures as well as by their reprocessability via compression molding and extrusion. Additionally, the materials were degraded under weak acidic conditions, and the starting biobased polyol was recovered in a yield of 72%, thus enabling a closed-loop chemical recycling of this monomer.

An alternative route to synthesise TCNQ-CTF by using trifluoromethanesulfonic (TFMS) acid catalysis is presented, in comparison to a previously reported ZnCl₂-catalysed synthesis. The new synthetic route yields a polymer with additional structural diversity compared to the previously reported material. The composition of the framework is rationalised by ‘artificial’ acid-catalysed synthesis of TCNQ-CTF, together with a novel approach to structural feature identification, with a range of alternative structural features appearing that were not present in the previously reported polymer formed by ZnCl₂ catalysis. These results will inform the design of new CTF materials with additional functionality and broader applications.

Reversible addition–fragmentation chain transfer (RAFT) polymerization enables precise regulation of polymer chain growth and active center distribution. This study adopted a two-step approach with RAFT polymerization followed by quaternization to synthesize antibacterial materials, specifically tunable porous polymers PCaPE(Br) and PCaPE(I). The work focused on the structure–activity relationship between RAFT-derived block structures and the antibacterial properties of these materials. RAFT-mediated polymerization precisely controlled the block copolymer precursor PE-PDE, which is PEMA-b-P(DMAEA-co-EGDMA), and this control facilitated the subsequent formation of ordered porous structures. When the molar ratio of poly(ethyl methacrylate) (PEMA) to ethylene glycol dimethacrylate (EGDMA) was set to 1 : 6, the final quaternized products PCaPE₂(Br) and PCaPE₂(I) exhibited porous and fluffy microstructures. These microstructures were characterized by large specific surface area and high porosity. This structure, combined with uniformly distributed quaternary ammonium salt groups from the quaternization of N,N-dimethylaminoethyl acrylate (DMAEA) tertiary amine groups, enhanced the contact between antibacterial active sites and bacteria as well as antibacterial efficacy. PCaPE(Br) and PCaPE(I) showed excellent broad-spectrum antibacterial activity against E. coli and S. aureus. They also maintained good reusability with over 95% activity retention after five cycles. Such advantages support their prospects in biomedicine, agricultural antibacterials and wastewater treatment.

Previously, we reported the dependence of the propagation rate coefficient (k_p) for methacrylic acid (MAA) and sodium methacrylate (MAANa) on monomer concentration, degree of ionization, and temperature (I. Lacík, L. Učňová, S. Kukučková, M. Buback, P. Hesse and S. Beuermann, Macromolecules, 2009, 42, 7753–7761). In this study, we extend this work to investigate the ionization of MAA via a proton transfer mechanism in the presence of primary isobutylamine (IBA) and tertiary triethylamine (TEA), which differ in their affinity for the carboxylic proton. An advantage of these systems lies in their solubility in both water and non-polar solvents due to the presence of a hydrophobic group in the cation moiety. NMR and FTIR spectroscopy showed that complete proton transfer occurs for both monomers in water, and for MAA-IBA in DMSO. In contrast, MAA-TEA forms a hydrogen-bonded molecular complex in DMSO. The Kamlet–Taft α parameter was determined as a measure of the hydrogen bond donor ability of these systems. The k_p values for these MAA-amine monomers were determined in water and DMSO over a monomer concentration range of 0.45–1.82 mol L⁻¹ and a temperature range of 20–60 °C, using pulsed laser polymerization coupled with size-exclusion chromatography. In both solvents, the k_p values for MAA-IBA are lower than those for MAA-TEA, with the difference being modest in water (up to a factor of 2) and more pronounced in DMSO (up to a factor of 4). The influence of monomer concentration on k_p is less significant than for MAANa. Activation energies, E_A(k_p), increase from 19.3 ± 1.5 and 17.8 ± 0.3 kJ mol⁻¹ in water to 28.2 ± 1.6 and 26.9 ± 1.7 kJ mol⁻¹ in DMSO for MAA-IBA and MAA-TEA, respectively. The pre-exponential factor ∼0.9 × 10⁶ L mol⁻¹ s⁻¹ is similar for both monomers in water and is increased by an order of magnitude in DMSO. These results demonstrate that k_p depends on monomer speciation and a complex interplay between electrostatic, hydrogen bonding, and hydrophobic interactions.

A divergent synthetic scheme based on copper-free click chemistry was used to obtain two types of bromine-containing dendrimers with a thiacalix[4]arene or gallic acid core. These dendrimers were then terminated with cationic imidazolium groups via the Menshutkin reaction to obtain a series of amphiphilic dendrimers. The critical aggregation concentrations of the dendrimers were determined using three different probes. It was demonstrated that the solubilization capacity with respect to the hydrophobic Orange OT substrate logically increases with the transition from the second to the third generation, whereas the first generation does not solubilize the dye. In the case of the thiacalix[4]arene core, the most compact aggregates (approximately 80 nm) were obtained in the second generation. In the case of gallic acid, the most compact aggregates (approximately 30 nm) were obtained in the second and third generations, with the third generation forming the most monodisperse particles. Steady-state and time-resolved fluorescence spectroscopy revealed that the third generation on both the gallic acid and thiacalix[4]arene platforms interacts most effectively with calf thymus DNA, displacing ethidium bromide. The addition of third-generation dendrimers causes DNA compaction, forming particles measuring approximately 70–120 nm, and results in surface recharging to +40 mV. Since the CD data show that the addition of dendrimers results in DNA ordering (transition to the C-form), the obtained second- and third-generation dendrimers are promising as potential matrices for stabilization, storage, or delivery of nucleic acids in future studies.

Due to the contradictory molecular design principles required to achieve both high mobility and strong luminescence, the development of polymer semiconductors that simultaneously possess these characteristics remains a significant challenge. To address this issue, the development of structurally innovative conjugated polymers is highly desired. Herein, two dithienocyclopentapyrene (PyDT) donor units with either centro- or axial-symmetry were designed and synthesized, and subsequently copolymerized with a benzothiadiazole (BT) acceptor to afford cs-PyDT-BT and as-PyDT-BT. The resulting polymers exhibit pronounced position- and molecular-weight-dependent characteristics. Specifically, cs-PyDT-BT displays low crystallinity and a nearly amorphous microstructure, yet achieves higher charge-carrier mobility and intense red emission (∼670 nm) relative to its counterpart as-PyDT-BT, which shows higher crystallinity, lower mobility, and a red-shifted emission (∼690 nm). Furthermore, the influence of molecular weight was systematically investigated for cs-PyDT-BT. As the molecular weight increased, the film-state photoluminescence quantum yield (PLQY) gradually decreased, with the maximum value reaching 22%, while the highest mobility of 1 cm² V⁻¹ s⁻¹ was obtained at a medium M_n of approximately 100 kDa. This molecular design strategy provides new insights for developing next-generation conjugated polymers that combine strong luminescence with high mobility, thereby advancing multifunctional integrated polymeric materials.