Search Results (42)

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

In this study, we explore the design of novel random poly(lauryl methacrylate-co-tert-butyl methacrylate-co-methacrylic acid), P(LMA-co-tBMA-co-MAA) copolymers via the RAFT copolymerization of LMA and tBMA followed by the selective hydrolysis of tBMA segments. For the molecular characterization of the novel copolymer, a series of physicochemical techniques were implemented, including size exclusion chromatography (SEC), proton nuclear magnetic resonance (¹H-NMR) and attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy. Our experimental results confirmed the successful synthesis of the targeted copolymers. The compositions were in accordance with the targeted differing fraction of hydrophobic tBMA/LMA elements, and hydrolysis resulted in at least 64% conversion to hydrophilic MAA units. The copolymers, bearing both an amphiphilic character and polyelectrolyte properties while being composed of randomly distributed monomeric segments of biocompatible materials, were subsequently investigated in terms of their self-assembly behavior in aqueous solutions. Dynamic light scattering and fluorescence spectroscopy experiments demonstrated the formation of self-assembled nanoaggregates (average hydrodynamic radii, R_h < 100 nm) that formed spontaneously, having low critical aggregation concentration (CAC) values (below 3.5 × 10⁻⁶ g/mL), and highlighted the feasibility of using these copolymer systems as nanocarriers for biomedical applications. Full article

Porous polymer membranes with highly interconnected open-cellular structure and high toughness are crucial for various application fields. Polymerized high internal phase emulsions (polyHIPEs), which usually exist as monoliths, possess the advantages of high porosity and good connectivity. However, it is difficult to prepare membranes due to brittleness and easy pulverization. Copolymerizing acrylate soft monomers can effectively improve the toughness of polyHIPEs, but it is easy to cause emulsion instability and pore collapse. In this paper, stable HIPEs with a high content of butyl acrylate (41.7 mol% to 75 mol% based on monomers) can be obtained by using a composite emulsifier (30 wt.% based on monomers) consisting of Span80/DDBSS (9/2 in molar ratio) and adding 0.12 mol·L⁻¹ CaCl₂ according to aqueous phase concentration. On this basis, polyHIPE membranes with high open-cellular extent and high toughness are firstly prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization. The addition of the RAFT agent significantly improves the mechanical properties of polyHIPE membranes without affecting open-cellular structure. The toughness of polyHIPE membranes prepared by RAFT polymerization is significantly enhanced compared with conventional free radical polymerization. When the molar ratio of butyl acrylate/styrene/divinylbenzene is 7/4/1, the polyHIPE membrane prepared by RAFT polymerization presents plastic deformation during the tensile test. The toughness modulus reaches 93.04 ± 12.28 kJ·m⁻³ while the open-cellular extent reaches 92.35%, and it also has excellent thermal stability. Full article

In this study, PMMA/SiO₂ composites were fabricated with monodispersed SiO₂ and PMMA using four distinct methods—physical blending, in situ polymerization, random copolymerization, and block copolymerization—to investigate the composites’ thermal, mechanical, and optical properties. In the physical blending approach, SiO₂ nanoparticles were dispersed in a PMMA solution, while during in situ polymerization, silica nanoparticles were incorporated during the synthesis of PMMA/SiO₂ composites. 3-methacryloxypropyltrimethoxysilane (MPS) was modified on the SiO₂ surface to introduce the reactive double bonds. The MPS@SiO₂ was either random- or block-copolymerized with PMMA through RAFT polymerization. The PMMA/SiO₂ composites prepared via these different methods were characterized using FTIR, TGA, and DSC to determine their chemical structures, thermal degradation temperatures, and glass transition temperatures, respectively. Scanning electron microscopy (SEM) was employed to observe the microstructures and dispersion of the composites. This comprehensive analysis revealed that the PMMA/SiO₂ composites prepared via block copolymerization exhibited thermal stability at temperatures between 200 and 300 °C. Additionally, they demonstrated excellent transparency (86%) and scratch resistance (≥6H) while maintaining mechanical strength, suggesting their potential application in thermal insulation materials. Full article

A random copolymer (PTBM), utilized as deep ultra-violet (DUV) photoresist, was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization with tert-butyl methacrylate (tBMA), methyl methacrylate (MMA), triphenylsulfonium p-styrenesulfonate (TPS-SS), and functional poly (sesquicarbonylsiloxanes) (POSS-MA) as the monomer components, and 4-cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl]pentanoic acid (CDSPA) as the RAFT reagent. Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H NMR) proved successful synthesis. Ultraviolet absorption spectroscopy (UV) analysis verified the transparency of the polymer in the DUV band. RAFT polymerization kinetics showed that the polymerization rate conformed to the first-order kinetic relationship, and the polymerization process exhibited a typical controlled free radical polymerization behavior. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and static thermo-mechanical analysis (TMA) showed that the incorporation of POSS groups improved the thermal properties of the copolymer. According to scanning electron microscopy (SEM) images, the copolymerization of photoacid monomers (TPS-SS) resulted in photoresist copolymers exhibiting good resistance to acid diffusion and low roughness. Full article

This manuscript presents the synthesis of hyperbranched amphiphilic poly (lauryl methacrylate-co-tert-butyl methacrylate-co-methacrylic acid), H-P(LMA-co-tBMA-co-MAA) copolymers via reversible addition fragmentation chain transfer (RAFT) copolymerization of tBMA and LMA, and their post-polymerization modification to anionic amphiphilic polyelectrolytes. The focus is on investigating whether the combination of the hydrophobic characters of LMA and tBMA segments, as well as the polyelectrolyte and hydrophilic properties of MAA segments, both distributed within a unique hyperbranched polymer chain topology, would result in intriguing, branched copolymers with the potential to be applied in nanomedicine. Therefore, we studied the self-assembly behavior of these copolymers in aqueous media, as well as their ability to form complexes with cationic proteins, namely lysozyme (LYZ) and polymyxin (PMX). Various physicochemical characterization techniques, including size exclusion chromatography (SEC) and proton nuclear magnetic resonance (¹H-NMR), verified the molecular characteristics of these well-defined copolymers, whereas light scattering and fluorescence spectroscopy techniques revealed promising nanoparticle (NP) self- and co-assembly properties of the copolymers in aqueous media. Full article

Superparamagnetic iron oxide nanoparticles (SPION) with a “non-fouling” surface represent a versatile group of biocompatible nanomaterials valuable for medical diagnostics, including oncology. In our study we present a synthesis of novel maghemite (γ-Fe₂O₃) nanoparticles with positive and negative overall surface charge and their coating by copolymer P(HPMA-co-HAO) prepared by RAFT (reversible addition–fragmentation chain-transfer) copolymerization of N-(2-hydroxypropyl)methacrylamide (HPMA) with N-[2-(hydroxyamino)-2-oxo-ethyl]-2-methyl-prop-2-enamide (HAO). Coating was realized via hydroxamic acid groups of the HAO comonomer units with a strong affinity to maghemite. Dynamic light scattering (DLS) demonstrated high colloidal stability of the coated particles in a wide pH range, high ionic strength, and the presence of phosphate buffer (PBS) and serum albumin (BSE). Transmission electron microscopy (TEM) images show a narrow size distribution and spheroid shape. Alternative coatings were prepared by copolymerization of HPMA with methyl 2-(2-methylprop-2-enoylamino)acetate (MMA) and further post-polymerization modification with hydroxamic acid groups, carboxylic acid and primary-amino functionalities. Nevertheless, their colloidal stability was worse in comparison with P(HPMA-co-HAO). Additionally, P(HPMA-co-HAO)-coated nanoparticles were subjected to a bio-distribution study in mice. They were cleared from the blood stream by the liver relatively slowly, and their half-life in the liver depended on their charge; nevertheless, both cationic and anionic particles revealed a much shorter metabolic clearance rate than that of commercially available ferucarbotran. Full article

In this work, we have developed a method for the preparation of pH-responsive track-etched membranes (TeMs) based on poly(ethylene terephthalate) (PET) with pore diameters of 2.0 ± 0.1 μm of cylindrical shape by RAFT block copolymerization of styrene (ST) and 4-vinylpyridine (4-VP) to be used in the separation of water–oil emulsions. The influence of the monomer concentration (1–4 vol%), the molar ratio of RAFT agent: initiator (1:2–1:100) and the grafting time (30–120 min) on the contact angle (CA) was studied. The optimal conditions for ST and 4-VP grafting were found. The obtained membranes showed pH-responsive properties: at pH 7–9, the membrane was hydrophobic with a CA of 95°; at pH 2, the CA decreased to 52°, which was due to the protonated grafted layer of poly-4-vinylpyridine (P4VP), which had an isoelectric point of pI = 3.2. The obtained membranes with controlled hydrophobic-hydrophilic properties were tested by separating the direct and reverse “oil–water” emulsions. The stability of the hydrophobic membrane was studied for 8 cycles. The degree of purification was in the range of 95–100%. Full article

The radical statistical copolymerization of N–vinyl pyrrolidone (NVP) and 2–chloroethyl vinyl ether (CEVE) was conducted using the Reversible Addition–Fragmentation chain Transfer (RAFT) polymerization technique, employing [(O–ethylxanthyl)methyl]benzene (CTA-1) and O–ethyl S–(phthalimidylmethyl) xanthate (CTA-2) as the Chain Transfer Agents (CTAs), leading to P(NVP–stat–CEVE) products. After optimizing copolymerization conditions, monomer reactivity ratios were estimated using various linear graphical methods, as well as the COPOINT program, which was applied in the framework of the terminal model. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the monomers’ mean sequence lengths. Thermal properties of the copolymers were studied by Differential Scanning Calorimetry (DSC) and kinetics of their thermal degradation by Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG), applying the isoconversional methodologies of Ozawa–Flynn–Wall (OFW) and Kissinger–Akahira–Sunose (KAS). Full article

The synthesis of novel copolymers using one-step reversible addition-fragmentation chain transfer (RAFT) copolymerization of biocompatible methacrylic acid (MAA), lauryl methacrylate (LMA), and difunctional ethylene glycol dimethacrylate (EGDMA) as a branching agent is reported. The obtained amphiphilic hyperbranched H-P(MAA-co-LMA) copolymers are molecularly characterized by size exclusion chromatography (SEC), FTIR, and ¹H-NMR spectroscopy, and subsequently investigated in terms of their self-assembly behavior in aqueous media. The formation of nanoaggregates of varying size, mass, and homogeneity, depending on the copolymer composition and solution conditions such as concentration or pH variation, is demonstrated by light scattering and spectroscopic techniques. Furthermore, drug encapsulation properties are studied by incorporating the low bioavailability drug, curcumin, in the nano-aggregate hydrophobic domains, which can also act as a bioimaging agent. The interaction of polyelectrolyte MAA units with model proteins is described to examine protein complexation capacity relevant to enzyme immobilization strategies, as well as explore copolymer self-assembly in simulated physiological media. The results confirm that these copolymer nanosystems could provide competent biocarriers for imaging and drug or protein delivery/enzyme immobilization applications. Full article

Functional crosslinked hydrogels were prepared from 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA). The acid monomer was incorporated both via copolymerization and chain extension of a branching, reversible addition–fragmentation chain-transfer agent incorporated into the crosslinked polymer gel. The hydrogels were intolerant to high levels of acidic copolymerization as the acrylic acid weakened the ethylene glycol dimethacrylate (EGDMA) crosslinked network. Hydrogels made from HEMA, EGDMA and a branching RAFT agent provide the network with loose-chain end functionality that can be retained for subsequent chain extension. Traditional methods of surface functionalization have the downside of potentially creating a high volume of homopolymerization in the solution. Branching RAFT comonomers act as versatile anchor sites by which additional polymerization chain extension reactions can be carried out. Acrylic acid grafted onto HEMA–EGDMA hydrogels showed higher mechanical strength than the equivalent statistical copolymer networks and was shown to have functionality as an electrostatic binder of cationic flocculants. Full article

A series of diphosphine Re(I) complexes Re1–Re4 have been designed via decoration of the archetypal core {Re(CO)₂(N^N)} through the installations of the phosphines P⁰ and P¹ bearing the terminal double bond, where N^N = 2,2′-bipyridine (N^N1), 4,4′-di-tert-butyl-2,2′-bipyridine (N^N2) or 2,9-dimethyl-1,10-phenanthroline (N^N3) and P⁰ = diphenylvinylphosphine, and P¹ = 4-(diphenylphosphino)styrene. These complexes were copolymerized with the corresponding N-vinylpyrrolidone-based Macro-RAFT agents of different polymer chain lengths to give water-soluble copolymers of low-molecular p(VP-l-Re) and high-molecular p(VP-h-Re) block-copolymers containing rhenium complexes. Compounds Re1–Re4, as well as the copolymers p(VP-l-Re) and p(VP-h-Re), demonstrate phosphorescence from a ³MLCT excited state typical for this type of chromophores. The copolymers p(VP-l-Re#) and p(VP-h-Re#) display weak sensitivity to molecular oxygen in aqueous and buffered media, which becomes almost negligible in the model physiological media. In cell experiments with CHO-K1 cell line, p(VP-l-Re2) and p(VP-h-Re2) displayed significantly reduced toxicity compared to the initial Re2 complex and internalized into cells presumably by endocytic pathways, being eventually accumulated in endosomes. The sensitivity of the copolymers to oxygen examined in CHO-K1 cells via phosphorescence lifetime imaging microscopy (PLIM) proved to be inessential. Full article

Within the era of battery technology, the urgent demand for improved and safer electrolytes is immanent. In this work, novel electrolytes, based on pyrrolidinium-bistrifluoromethanesulfonyl-imide polymeric ionic liquids (POILs), equipped with quadrupolar hydrogen-bonding moieties of ureido-pyrimidinone (UPy) to mediate self-healing properties were synthesized. Reversible addition–fragmentation chain-transfer (RAFT) polymerization was employed using S,S-dibenzyl trithiocarbonate as the chain transfer agent to produce precise POILs with a defined amount of UPy and POIL-moieties. Kinetic studies revealed an excellent control over molecular weight and polydispersity in all polymerizations, with a preferable incorporation of UPy monomers in the copolymerizations together with the ionic monomers. Thermogravimetric analysis proved an excellent thermal stability of the polymeric ionic liquids up to 360 °C. By combining the results from differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS), and rheology, a decoupled conductivity of the POILs from glass transition was revealed. While the molecular weight was found to exert the main influence on ionic conductivity, the ultimate strength and the self-healing efficiency (of up to 88%) were also affected, as quantified by tensile tests for both pristine and self-healed samples, evidencing a rational design of self-healing electrolytes bearing both hydrogen bonding moieties and low-molecular-weight polymeric ionic liquids. Full article

Alternating donor–acceptor conjugated polymers, widely investigated due to their applications in organic photovoltaics, are obtained mainly by cross-coupling reactions. Such a synthetic route exhibits limited efficiency and requires using, for example, toxic palladium catalysts. Furthermore, the coating process demands solubility of the macromolecules, provided by the introduction of alkyl side chains, which have an impact on the properties of the final material. Here, we present the synthetic route to ladder-like donor–acceptor polymer brushes using alternating copolymerization of modified styrene and maleic anhydride monomers, ensuring proper arrangement of the pendant donor and acceptor groups along the polymer chains grafted from a surface. As a proof of concept, macromolecules with pendant thiophene and benzothiadiazole groups were grafted by means of RAFT and metal-free ATRP polymerizations. Densely packed brushes with a thickness up to 200 nm were obtained in a single polymerization process, without the necessity of using metal-based catalysts or bulky substituents of the monomers. Oxidative polymerization using FeCl₃ was then applied to form the conjugated chains in a double-stranded (ladder-like) architecture. Full article

Studies have shown the possibility of synthesizing new polymers based on polypropylene glycol maleate with acrylic acid in the presence of a RAFT agent (2-Cyano-2-propyl dodecyl trithiocarbonate CPDT). The effect of RAFT agent concentration on network density has been shown to be connected with product yield. Herein, the composition of the obtained copolymers was determined using FTIR spectrometry in combination with the chemometric method of partial least squares (or projection to latent structures). To investigate the synthesized hydrogels, the degrees of equilibrium swelling was studied. The resulting objects were characterized by infrared spectroscopy. The surface morphology of the polymers was studied and the pore sizes were estimated using scanning electron microscopy. The structure of the test samples was confirmed by NMR spectroscopy. The thermal stability of crosslinked polymers was determined using thermogravimetry. Full article