Search Results (260)

Reversible addition–fragmentation chain-transfer (RAFT) polymerization has become an efficient method in the field of polymer synthesis. Recently, the RAFT polymerization technique has been successfully used to prepare functional materials and develop various sensing methods used in different scenarios. The polymerization reaction can be initiated by thermal, electrochemical, photochemical, enzymatic, and mechanical stimulation. More interestingly, RAFT polymerization can be performed in situ by recruiting a large number of signal tags at the solid interface to amplify the signals. In this review, we addressed the latest achievements in the preparation of sensing materials and the design of different sensors based on the RAFT polymerization technique for sensing ions and small molecules and bioimaging of tumor cells and viruses. Then, electrochemical and optical biosensors through the signal amplification of the RAFT polymerization method were summarized. This work could provide inspiration for researchers to prepare fascinating sensing materials and develop novel detection technologies applied in various fields. Full article

Novel universal bulk-fill composites with reversible addition–fragmentation chain-transfer (RAFT)-modulated polymerization continue the trend towards increasing simplification of the restoration process to facilitate the reconstruction of deep posterior restorations in 4 mm increments as well as anterior restorations through improved aesthetics. This study aims to assess the suitability of such materials for rapid curing (3 s) with high-radiant emittance in terms of degree of conversion (DC) and polymerization kinetics at relevant depths (2 mm vs. 4 mm). For this purpose, two newly introduced bulk-fill universal composites (Tetric^® plus Flow and Tetric^® plus Fill) were compared with already established fast-curing composites (Tetric^® Power Flow and Tetric^® Power Fill). DC was measured in real time over 300 s using ATR-FTIR spectroscopy. The temporal DC evolution was modelled using an exponential sum function. Novel bulk-fill composites showed DC results that were independent of the measured sample depth or curing mode. The polymerization kinetics of all composites are somewhat slower in the gel phase at moderate irradiance or when measured at deeper layers, but compensate for the differences in the glass phase, finally reaching equivalent DC values by the end of the 300-s observation period. These novel composites are therefore suitable for rapid curing (3 s) at high irradiance. Full article

Herein, we report a combined computational and experimental investigation into the recently reported universal pyrazole-based reversible addition-fragmentation chain transfer (RAFT) agents (Z−C(=S)−S−R, where Z is 3,5-dimethyl-1H-pyrazol-1-yl), which can mediate controlled radical polymerization of a broad scope of monomers without the need for an additional initiator or catalyst. The results reveal that the high molar absorption coefficient and efficient photolysis kinetics of pyrazole-based chain transfer agents (CTAs) under blue light (${\lambda }_{\max }$ = 465 nm) enable rapid radical generation, underpinning ultrafast polymerization of acrylates, acrylamides, methacrylates, and N-vinylpyrrolidone (NVP). While the efficient light absorption is attributed to structural dissimilarity between the Z group and the S–R group (which breaks the local symmetry of the C=S group), the fast photolysis originates from favorable $\pi$ electron donation from the Z group to the C=S group. Meanwhile, the $\pi$ electron donation is still weaker than in xanthates, which explains the excellent control of a wide range of monomers, except methacrylates. This work establishes design principles for next-generation CTAs for ultrafast and monomer-universal photoiniferter RAFT polymerization. Full article

The emergence of bacterial resistance has spurred an urgent need to develop effective alternatives to traditional antibiotics. Phenylethyl alcohol from plants exhibits potential antimicrobial properties, but its efficacy is limited due to its compromised dispersion in water and structural stability in ambient conditions. Herein, for the first time, a polymerization-induced self-assembly strategy was employed to obtain different morphological nanogels with phenylethyl alcohol moieties as hydrophobic cores through in situ reversible addition–fragmentation chain-transfer (RAFT) polymerization. The well-defined copolymers of PTEG_x-co-PPMA_y with controllable molecular weights and narrow polydispersity were confirmed by a combination of techniques. The generated phenylethyl alcohol-based nanogels demonstrated potent antibacterial activity, particularly PTEG₃₀-co-PPMA₇₀ with a one-dimensional linear architecture, which achieved a minimum inhibitory concentration of 62 μg mL⁻¹ against E. coli. SEM revealed membrane disruption as the bactericidal mechanism, highlighting enhanced efficacy against Gram-negative bacteria due to structural differences in cell envelopes. This study establishes a robust platform for designing phenylethyl alcohol-based nanogels with controllable structures toward achieving potent antimicrobial performance, offering a promising strategy for combating bacterial resistance while addressing the dilemma of conventional antibiotic drug systems. Full article

Fe³⁺-incorporated hydrogels are particularly valuable for wearable devices due to their tunable mechanical properties and ionic conductivity. However, conventional immersion-based fabrication fundamentally limits hydrogel performance because of heterogeneous ion distribution, ionic leaching, and scalability limitations. To overcome these challenges, we report a novel one-pot strategy where controlled amounts of Fe³⁺ are directly added to polyacrylamide-sodium acrylate (PAM-SA) precursor solutions, ensuring homogeneous ion distribution. Combining this with Photoinduced Electron/Energy Transfer Reversible Addition–Fragmentation Chain Transfer (PET-RAFT) polymerization enables efficient hydrogel fabrication under open-vessel conditions, improving its scalability. Fe³⁺ concentration achieves unprecedented modulation of mechanical properties: Young’s modulus (10 to 150 kPa), toughness (0.26 to 2.3 MJ/m³), and strain at break (800% to 2500%). The hydrogels also exhibit excellent compressibility (90% strain recovery), energy dissipation (>90% dissipation efficiency at optimal Fe³⁺ levels), and universal adhesion to diverse surfaces (plastic, metal, PTFE, and cardboard). Finally, these Fe³⁺-incorporated hydrogels demonstrated high effectiveness as strain sensors for monitoring finger/elbow movements, with gauge factors dependent on composition. This work provides a scalable, oxygen-tolerant route to tunable hydrogels for advanced wearable devices. Full article

Microbial contamination is a global concern with impacts on a variety of industries ranging from marine to biomedical applications. Recent research on hydrophilic polymer-based coatings is focused on combining antifouling polymers with nanomaterials to enhance mechanical, optical, and stimuli-responsive properties, yielding colour changing, self-healing, and super hydrophilic materials. This study combines the hydrophilic and antifouling properties of vitamin B5 analogous methacrylamide (B5AMA)-based polymers with stimuli-responsive anthocyanin-dye-loaded cellulose nanocrystals (CNCs) to develop antifouling materials with colour changing capabilities upon bacterial contamination. Poly(B5AMA)-grafted CNCs were prepared through surface-initiated photoiniferter reversible addition fragmentation chain transfer (SP-RAFT) polymerization and characterized through proton nuclear magnetic resonance (¹H-NMR), transmission electron microscopy (SEM/TEM), and X-ray photon spectroscopy (XPS) to confirm the formation of surface-grafted polymer chains. The bare CNCs and poly(B5AMA)-grafted CNCs were loaded with anthocyanin dye and evaluated for pH-dependent colour changing capabilities. Interestingly, anthocyanin-loaded CNCs demonstrated vibrant colour changes in both solution and dried film form upon bacterial contamination; however, limited colour changing capabilities of the composites, specifically in dried film form, were attributed to the enhanced dispersibility and antifouling capabilities of the polymer-coated CNCs. Full article

Carbon dots (CDs), a class of carbon-based fluorescent nanomaterials, have garnered significant attention due to their tunable optical properties and functional versatility. In this study, we developed a hybrid material by grafting pH- and temperature-responsive copolymers onto CDs via reversible addition-fragmentation chain-transfer (RAFT) polymerization. Triamino-tetraphenylethylene (ATPE) and N-isopropylacrylamide (NIPAM) were copolymerized at varying ratios and covalently linked to CDs, forming a dual-responsive system. Structural characterization using FTIR, ¹H NMR, and TEM confirmed the successful grafting of the copolymers onto CDs. The hybrid material exhibited pH-dependent fluorescence changes in acidic aqueous solutions, with emission shifting from 450 nm (attributed to CDs) to 500 nm (aggregation-induced emission, AIE, from ATPE) above a critical pH threshold. Solid films of the hybrid material demonstrated reversible fluorescence quenching under HCl vapor and recovery/enhancement under NH₃ vapor, showing excellent fatigue resistance over multiple cycles. Temperature responsiveness was attributed to the thermosensitive poly(NIPAM) segments, with fluorescence intensity increasing above 35 °C due to polymer chain collapse and ATPE aggregation. This work provides a strategy for designing multifunctional hybrid materials with potential applications in recyclable optical pH/temperature sensors. Full article

Postoperative adhesions are a prevalent complication following abdominal surgeries, often leading to significant clinical challenges. This study introduces an innovative solution utilizing a polyethylene glycol (PEG)-based triblock copolymer to form an injectable, self-healing hydrogel aimed at preventing these adhesions. The hydrogel, formulated with temperature-responsive and self-healing properties through the incorporation of poly (N-isopropyl acrylamide) (PNIPAM) and anion–pi interactions, was synthesized using reversible addition–fragmentation chain transfer (RAFT) polymerization. The hydrogel’s physical properties, biocompatibility, hemostatic effect, and anti-adhesive capabilities were rigorously tested through in vitro and in vivo experiments involving rat models. It demonstrated excellent biocompatibility, effective tissue adhesion, and robust hemostatic properties. Most notably, it exhibited significant anti-adhesive effects in a rat abdominal wall–cecum model, reducing adhesion formation effectively compared to controls. The PEG-based injectable hydrogel presents a promising approach for postoperative adhesion prevention. Its ability to gel in situ triggered by body heat, coupled with its self-healing properties, provides a substantial advantage in clinical settings, indicating its potential utility as a novel anti-adhesion material. Full article

Amphiphilic diblock copolymers comprising polyethylene glycol (PEG) and 1-vinyl imidazole (VIM) were synthesized using reversible addition–fragmentation chain transfer (RAFT) polymerization. The study focused on the synthesis of well-defined nanostructures with tunable composition and their functional modification for biomedical applications. The successful polymerization of PEG-b-PVIM diblock copolymers was confirmed via ¹H NMR spectroscopy, and their molecular weights were analyzed using gel permeation chromatography (GPC). The copolymers exhibited pH-responsive behavior, with effective pK values of approximately 4.2. To facilitate radiolabeling and in vivo tracking, a post-polymerization modification enabled the conjugation of a 1,4,7-Triazacyclononane-1,4,7-triacetic acid (NOTA) chelator via aminolysis. The final conjugates were purified and characterized, confirming successful functionalization. These findings highlight the potential of PEG_x-b-PVIM_y diblock copolymers for biomedical applications. Full article

CO₂-responsive polymers have emerged as a significant class of smart materials, distinguished by their ability to reversibly alter their properties upon exposure to CO₂. Due to CO₂’s abundant availability, low cost, non-toxicity, energy efficiency, and excellent biocompatibility, these polymers offer remarkable environmental and practical advantages. This review succinctly explores recent advancements in the synthesis, mechanisms, and applications of CO₂-responsive polymers, emphasizing the pivotal roles of specific acidic and basic functional groups such as carboxylic acids, phenolic groups, amines, amidines, guanidines, and imidazoles. Advanced polymerization techniques including free radical polymerization (FRP), atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT), and nitroxide-mediated polymerization (NMP) are critically evaluated for their precision and flexibility in polymer design. Significant applications in smart separation, carbon capture, drug delivery, desalination, emulsions, tissue engineering, and sensing technologies are discussed comprehensively. Although substantial progress has been made, ongoing challenges include enhancing response speed, durability, sustainability, and economic viability. Future research is recommended to focus on innovative polymer structures, computational modeling, hybrid materials, and greener synthesis methods. This review aims to inspire continued exploration and practical utilization of CO₂-responsive polymers to address pressing environmental and technological needs. Full article

Reversible addition–fragmentation chain-transfer (RAFT) polymerization was used to synthesize novel thermoresponsive cationic molecular brushes with high yields—namely of copolymers of methoxyoligo(ethylene glycol) methacrylate, alkoxyoligo(ethylene glycol) methacrylate, and N-methacryloylaminopropyl-N,N-dimethyl-N-propylammonium bromide. Controlled polymerization yielded polymers with a molecular weight dispersity of ≤1.3 and conversions exceeding 80%. The influence of the cationic molecular brushes’ composition on their solubility in water and organic solvents, interfacial tension at the water–oil interface, and aggregation behavior in aqueous solutions was investigated. For the first time, we report the design of thermoresponsive cationic molecular brushes combining an antibacterial potential and tunable hydrophilic–hydrophobic properties, enabling highly precise control over their LCST behavior (17–68 °C) through composition tuning. The solubilization capacity of the hydrophobic compounds of brush micelles in water increased with the hydrophobic comonomer content. These polymers exhibited interfacial activity, significantly reducing the water–oil interfacial tension, with critical micelle concentrations (CMCs) of 3–10 mg/L. It was shown that the amphiphilic properties of the copolymers in aqueous solutions can be easily tuned in a desired direction by varying the content of the comonomer units. The obtained data indicate the potential of the polymers as micellar nanocarriers for controlled drug delivery. Full article

The kinetic model is a crucial tool for optimizing polymer synthesis protocols and facilitating the scaled-up production processes of the CO₂-responsive polymer poly(N-[3-(dimethylamino)propyl]-acrylamide)-b-poly(methyl methacrylate)(PDMAPAm-b-PMMA), which is supposed to be implemented in direct air capture (DAC) technology. This study presents a simulation of the kinetic model developed for the Reversible Addition−Fragmentation Chain-Transfer (RAFT) polymerization of N-[3-(dimethylamino)propyl]-acrylamide (DMAPAm), alongside an investigation into the kinetics of this polymerization using the simulation as an analytical tool, as well as the application of the simulation for the upscaling of RAFT polymerization. Ultimately, the kinetic model was validated through two kinetic experiments, confirming its reliability. It was subsequently employed to optimize the synthesis recipe and to predict the properties of PDMAPAm homopolymers, thereby supporting the upscaling of PDMAPAm-b-PMMA diblock copolymer synthesis. In the end, the preliminary results of the CO₂-responsiveness of the diblock copolymer were determined with a simple experiment. Full article

In this study, novel triblock copolymers, including poly(N-isopropylacrylamide)-block-poly(ε-caprolactone)-block-poly(N-isopropylacrylamide) (PNIPAM-b-PCL-b-PNIPAM), poly(N-vinyl-pyrrolidone)-block-poly(ε-caprolactone)-block-poly(N-vinyl-pyrrolidone) (PNVP-b-PCL-b-PNVP), poly(N-isopropylacrylamide-co-N,N-dimethylaminoethyl methacrylate)-block-poly(ε-caprolactone)-block-poly(N-isopropylacrylamide-co-N,N-dimethylaminoethyl methacrylate) (P(DMAEMA-co-NIPAM)-b-PCL-b-P(NIPAM-co-DMAEMA)), and poly(N,N-dimethylacrylamide)-block-poly(ε-caprolactone)-block-poly(N,N-dimethylacrylamide) (PDMA-b-PCL-b-PDMA), were synthesized via a combination of ring-opening polymerization (ROP) and reversible addition–fragmentation chain transfer (RAFT) polymerization. The synthesis was performed using novel bifunctional PCL-based RAFT macro chain transfer agents (macroCTAs; MXTPCL-X1 and MXTPCL-X2) with a m-xylene-bis(2-mercaptoethyloxy) core. Initially, m-xylene-bis(1-hydroxy-3-thia-propane) (MXTOH), which has not previously been used in lactone polymerization, was synthesized via the reaction of α,α′-dibromo-m-xylene with 2-mercaptoethanol in the presence of sodium in ethanol. Subsequently, Sn(Oct)₂-catalyzed ROP of ε-caprolactone (ε-CL) using MXTOH as an initiator yielded PCL-diol (MXTPCLOH). The resulting PCL-diol underwent further functionalization through esterification and substitution reactions, leading to the formation of PCL-based RAFT macroCTAs. Triblock copolymers were synthesized using these macroCTAs with AIBN as an initiator. The synthesized products, along with their intermediates, were characterized using FTIR and ¹H NMR spectroscopy. The number average molecular weight (M_n) and polydispersity index (Ð) of PCL-based macroCTAs were determined by using GPC analysis. The sensor capabilities of the synthesized novel triblock copolymers were investigated on the determination of syringic acid and it was determined that the most sensitive polymer was PNVP-b-PCL-b-PNVP (MXTP2). The working range was between 1.5 µg/mL and 15 µg/mL and the limit of detection (LOD) was found to be 0.44 µg/mL using DPV on MXTP2 polymer sensor. Full article

Amphiphilic block copolymers are essential for developing advanced polymer nanomaterials with applications in bioimaging, drug delivery, and nanoreactors. In this study, we successfully synthesized functional block copolymer assemblies at high concentrations through redox-initiated reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of 2-(acetoacetoxy)ethyl methacrylate (AEMA), a β-ketoester functional monomer. Utilizing a redox initiation system at 50 °C, we produced poly(poly(ethylene glycol) methyl ether methacrylate)-b-PAEMA (PPEGMA_n-PAEMA_m). Kinetic studies demonstrated rapid monomer conversion exceeding 95% within 30 min, with distinct polymerization phases driven by micelle formation and monomer depletion. Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) revealed the formation of diverse morphologies, including worm-like, vesicular structures, and spherical micelles, depending on the macro-CTA molecular weight and monomer concentration. Additionally, post-polymerization modification with aggregation-induced emission (AIE) luminogens, such as 1-(4-aminophenyl)-1,2,2-tristyrene (TPE-NH₂), resulted in AIE-active polymer assemblies exhibiting strong fluorescence in aqueous dispersions. These AIE-active polymer assemblies also exhibited good biocompatibility. These findings demonstrate the efficacy of redox-initiated RAFT emulsion polymerization in fabricating functional, scalable block copolymer assemblies with potential applications in the field of life sciences. Full article

In this project, a new class of temperature- and pH-sensitive hydrogel consisting of N-isopropyl acrylamide (NIPAM), hydroxyethyl methacrylate (HEMA), and acrylamide (AAm) was prepared via a controlled route through the reversible addition–fragmentation chain-transfer (RAFT) polymerization process. Poly(ethyleneglycol) dimethacrylate (PEG-DMA) was used as a long-chain hydrophilic and biocompatible crosslinking agent. The hydrogel structure was confirmed by different characteristic techniques such as ¹H NMR, FT-IR, and SEC, and the morphology and particle diameters were checked via the scanning electron microscopy (SEM) and dynamic light scattering (DLS) methods. Afterward, the as-prepared hydrogel, poly(NIPAM-co-HEMA-co-AAm), was loaded with doxorubicin (DOX) to be used as a temperature- and pH-triggered delivery carrier. The prepared system released DOX slowly at 37 °C and neutral pH, but increased DOX release significantly at 42 °C and acidic pH. The anti-cancer efficiencies of free DOX, hydrogel, and the DOX–hydrogel conjugate were tested in vitro using human colorectal adenocarcinoma HT-29 cell lines. Cytotoxicity evaluation of free DOX compared with the DOX–hydrogel conjugate revealed that more cancer cells were killed with increasing concentration. Moreover, the DOX-mediated apoptosis and ROS levels showed the beneficial effects of poly(NIPAM-co-HEMA-co-AAm) hydrogel for cancer drug delivery. Generally, the results suggest that this system can be a potential candidate for designing drug delivery systems. Full article