Radical Polymerization Technique Research Articles

RAFT Polymerization for Advanced Morphological Control: From Individual Polymer Chains to Bulk Materials.

Control of the morphology of polymer systems is achieved through reversible-deactivation radical polymerization techniques such as Reversible Addition-Fragmentation chain Transfer (RAFT). Advanced RAFT techniques offer much more than just "living" polymerization - the RAFT toolkit now enables morphological control of polymer systems across many decades of length-scale. Morphological control is explored at the molecular-level in the context of syntheses where individual monomer unit insertion provides sequence-defined polymers (single unit monomer insertion, SUMI). By being able to define polymer architectures, the synthesis of bespoke shapes and sizes of nanostructures becomes possible by leveraging self-assembly (polymerization induced self-assembly, PISA). Finally, it is seen that macroscopic materials can be produced with nanoscale detail, based on phase-separated nanostructures (polymerization induced microphase separation, PIMS) and microscale detail based on 3D-printing technologies. RAFT control of morphology is seen to cross from molecular level to additive manufacturing length-scales, with complete morphological control over all length-scales.

Preparation and characterization of neural stem cell-loaded conductive hydrogel cochlear implant electrode coatings

Sensorineural deafness is a hearing impairment resulting from damage to the auditory nerve or inner ear hair cells. Currently, cochlear implants (CIs) are widely used as hearing aids for sensorineural deafness patients. A fundamental limitation of cochlear implants (CIs) is that spiral ganglion neurons (SGNs) cannot be replenished. This greatly restricts the rehabilitation of sensorineural deafness. Additionally, the insertion of CIs can cause secondary cochlear damage, worsening the condition of the patients' cochlear. Therefore, a new type of neural stem cells (NSCs) loaded graphene oxide-polyaniline/GelMA (GO-PAni/GelMA) conductive hydrogel electrode for cochlear implant was fabricated via in-situ radical polymerization and cyclic UV curing technique. On the one hand, the hydrogel electrode, as a direct contact layer, helps to avoid the physical hurt for cochlear. On the other hand, NSCs were supplemented via the hydrogel carrier and neuronal differentiation was induced by electrical stimulation, which was validated by the experimental results of immunofluorescence, Phalloidin Staining and RT-qPCR. Furthermore, based on RNA sequencing and transcriptome analysis, we hypothesized that the neuronal differentiation of NSCs was adjusted by the calcium signaling pathway and GABAergic synapse. Overall, our cell loading conductive hydrogel electrode may be an effective solution to sensorineural deafness. The revelation of the mechanism of neuronal differentiation promoted by electrical stimulation provides a basis for further sensorineural deafness treatment using conductive hydrogel CI electrode.

Behind the scenes of green chemistry: Glories and shadows of atom transfer radical polymerization environmental impact (E-factor)

The paper presents the evaluation of environmental impact (E-factor) as green chemistry metric, calculated for polymer synthesis via one of the most useful tools of macromolecular chemistry, which is atom transfer radical polymerization (ATRP), belonging to the reversible deactivation radical polymerization (RDRP) techniques. For the first time, experimentally determined polymerization yields were included in the calculation, by analyzing the polymer synthesis process using various organic solvents, different methods of regenerating the catalytic complex (meaning ATRP approach), or using the miniemulsion system as eco-friendly reaction medium and presenting the possibility of effective solvent recovery and reuse. The majority of the values of E-factor were below 16, falling within the scope intended for fine chemicals (5–50). The significant and innovative part of the presented research involves verifying the feasibility of using higher concentrations of the dispersed phase in the case of miniemulsion polymerization (increased to as much as 100 % vs. aqueous phase from a typical 20 %), while the use of recycled water allowed a 3-fold reduction in E-factor value. Polymerization in a miniemulsion environment is also attractive due to its low cost, considering the price of distilled water, which is over 580-fold lower than that of DMSO – a typical organic solvent. These observations allow for the reduction of environmental impact and process cost. Importantly, the observed trends in E-factor changes allowed for the identification of ATRP development directions in line with green chemistry and the circular economy.

Exploring the impact of poly(sodium styrene sulfonate) dispersants’ architecture on their performance in coal water slurry preparation

In this work, the architecture of poly(sodium styrene sulfonate) (PSSNa) dispersants were flexibly tailored by various strategies. Three categories of PSSNa dispersants with different topologies were obtained, namely, linear structured PSSNa (1-A-PSSNa), three-arm star PSSNa (3-AS-PSSNa) and six-arm star PSSNa (6-AS-PSSNa). The molecular weights (Mn) of these dispersants were adjusted in the range of 3200–26,200 g/mol by varying the feeding ratio of monomer to initiator. In addition, the polydispersity index (PDI) of resultant dispersants were also varied by using different polymerization technologies, such as atom transfer radical polymerization (ATRP) and conventional free radical polymerization technique (RP). Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) verified these architecture parameters of resultant PSSNa dispersants. Afterwards, the impact of these architectural factors on the performance of PSSNa dispersants in coal water slurry (CWS) preparation were evaluated. The results revealed that with the Mn of dispersants increased from 9800 to 26,200 g/mol, the apparent viscosity of CWS increased by around 11 %. The comparison between dispersants with approximate Mn (26,200 and 26,900 g/mol) and very different PDI (1.27 and 2.25) indicated that wide PDI are favourable for the performance. This work also confirmed that the topology of dispersants has a significant impact on their performance. The maximum coal loaded can increase from 63.9 % to 64.3 % when 1-A-PSSNa dispersant was replaced by 6-AS-PSSNa. Meanwhile, these architectural factors have a limited impact on the fluid type of CWSs, as all CWSs obtained in this work were pseudoplastic fluids regardless of the used dispersants. The potential mechanism was investigated using various technologies, such as the measurements of zeta potentials, contact angles, and low-field nuclear magnetic resonance spectra. The results revealed that topologizing did not alter the interaction between dispersant and coal surface. However, due to the special features of topological polymers, they can grant adsorbed coal particles with enhanced electrostatic repulsion and steric hindrance, which facilitated the dispersion of coal particles.

Tuning the Mechanical Properties of 3D-Printed Objects by Mixing Chain Transfer Agents in Norrish Type I Photoinitiated RAFT Polymerization.

Photoinduced 3D printing via photocontrolled reversible-deactivation radical polymerization (photoRDRP) techniques has emerged as a robust technique for creating polymeric materials. However, methods for precisely adjusting the mechanical properties of these materials remain limited. In this study, we present a facile approach for adjusting the mechanical properties of 3D-printed objects by adjusting the polymer dispersity within a Norrish type I photoinitiated reversible addition-fragmentation chain transfer (NTI-RAFT) polymerization-based 3D printing process. We investigated the effects of varying the concentrations and molar ratios of trithiocarbonate (BTPA) and xanthate (EXEP) on the mechanical properties of the printed materials. Our findings demonstrate that increased concentrations of RAFT agents or higher proportions of the more active BTPA lead to a decrease in Young's modulus and glass transition temperatures, along with an increase in elongation at break, which can be attributed to the enhanced homogeneity of the polymer network. Using a commercial LCD printer, the NTI-RAFT-based 3D printing system effectively produced materials with tailored mechanical properties, highlighting its potential for practical applications.

Design and optimization of acetazolamide nanoparticle-laden contact lens using statistical experimental design for controlled ocular drug delivery

This study aims to formulate and evaluate Eudragit nanoparticles-laden hydrogel contact lenses for controlled delivery of acetazolamide (ACZ) using experimental design. Eudragit S-100 was selected for the preparation of nanoparticles. The optimization of Eudragit S100 concentration (X1), polyvinyl alcohol concentration (X2), and the sonication time (X3) was attempted by applying a central composite experimental design. Mean size of nanoparticles (nm), percent in vitro drug release and drug leaching from the ACZ-ENs laden contact lens were considered as dependent variables. Nanoparticles-laden contact lens was prepared through the direct loading method and characterized. Optimum check-point formulation was selected based on validated quadratic polynomial equations developed using response surface methodology. The optimized formulation of ACZ-ENs exhibited spherical shape with a size of 244.3 nm and a zeta potential of −13.2 mV. The entrapment efficiency of nanoparticles was found to be 82.7 ± 1.21%. Transparent contact lenses loaded ACZ-ENs were successfully prepared using the free radical polymerization technique. ACZ-ENs incorporated in contact lens exhibited a swelling of 83.4 ± 0.82% and transmittance of 80.1 ± 1.23%. ACZ-ENs showed a significantly lower burst release of the drug when incorporated in the contact lens and release was sustained over a period of 24 h. The sterilized formulation of ACZ-ENs laden contact lens did not show any sign of toxicity in rabbit eyes. ACZ-ENs incorporated in contact lens could be considered as a potential alternative in glaucoma patients due to their ability to provide sustained drug release and thus enhance patient compliance.

Synthesis of locust bean gum/titanium dioxide hydrogel nanocomposites for efficient removal of methylene blue from aqueous solution

In this study, we are interested in preparing novel hydrogel and hydrogel nanocomposite-based adsorbents for removing methylene blue (MB) dye based on grafted locust bean gum (LBG). LBG hydrogel and hydrogel nanocomposite were synthesized using a radical polymerization technique in the absence and presence of TiO2 with LBG-cl-(acrylic acid (AA)-co-acrylamide (AAm)). Various analytical instruments Fourier transform infrared (FTIR), X-Ray diffraction (XRD), Scanning electron microscopy (SEM), and High-resolution transmission electron microscopy (HRTEM) were used to elucidate the chemical structure and surface morphology of the prepared samples. Using a batch adsorption experiment, the Langmuir isotherm model showed that LBG-cl-p(AA-co-AAm) hydrogel had a maximum adsorption capacity of 1540.9 mg/g and LBG-cl-(AA-co-AAm)/TiO2 hydrogel nanocomposites had a maximum adsorption capacity of 1273.4 mg/g at neutral pH. The thermodynamic data demonstrated that MB dye was removed via spontaneous adsorption. Furthermore, the regeneration study showed good recyclability for the obtained hydrogel nanocomposites through six consecutive reusable cycles. Therefore, the hydrogel nanocomposites are an effective adsorbent for the removal of MB dye from aqueous solutions.

Detection and adsorption of florfenicol in milk using bifunctional carbon dot-doped molecularly imprinted polymers.

Detection of florfenicol (FF) residues in animal-derived foods, as one of the most widely used antibiotics, is critically important to food safety. The fluorescent molecularly imprinted polymer (MIP) was synthesized by surface-initiated atom transfer radical polymerization technique with poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres, 4-vinylpyridine, ethylene glycol dimethacrylate, and FF as the matrix, functional monomer, crosslinker, and template molecule, respectively. Meanwhile, N-S co-doped carbon dot (CD) was synthesized with triammonium citrate and thiourea as precursors under microwave irradiation at 400W for 2.5min and then integrated into FF-MIP to obtain CD@FF-MIP. For comparison, non-imprinted polymer (NIP) without FF was also prepared. The adsorption capacity of CD@FF-MIP to FF reached 53.1mgg-1, which was higher than that of FF-MIP (34.7mgg-1), whereas the adsorption capacity of NIP was only 17.3mgg-1. The adsorption equilibrium of three materials was reached within 50min. Particularly, CD@FF-MIP exhibited an excellent fluorescence quenching response to FF in the concentration range of 3-50 µmolL-1. As a result, CD@FF-MIP was successfully utilized to extract FF in milk samples, which were analyzed by high-performance liquid chromatography. The standard recoveries were 95.8%-98.2%, and the relative standard deviation was 1.6%-4.2%. The method showed the advantages of simple operation, high sensitivity, excellent selectivity, and low cost, and also demonstrated a great application prospect in food detection.

Synthesis and Evaluation of Ph and Temperature Stimuli-Responsive Magnetic Nanohydrogels for Gene Delivery

The offer of gene delivery technologies as a promising approach to treating diverse diseases has revolutionized human medicine during the last two decades. So, the application of suitable vectors, particularly polymers with substrates with unique physicochemical properties for the transfer of targeted genes to logical sites for effective treatment, plays an indispensable role for more personalized medicine and improves the safety profile in response to continuing to use new medical technologies. For this purpose, we synthesized nanocarriers with a two-block cationic hydrogel, magnetic and non-magnetic, based on N-isopropyl acrylamide (NIPAM) and quaternary alkyl ammonium halide salts of DMAEMA (DMAEMAQ) with pH and temperature responsiveness via the free radical polymerization technique. The bulk properties of these co-polymers were characterized by using Fourier transform infrared spectroscopy, 1H NMR spectroscopy, Zeta potential, lower critical solution temperature (LCST), and gel electrophoresis to show the loading of nanoparticles with the gene. In the results, magnetic P[NIPAM-DMAEMAQ] hydrogel showed controllable responsive properties determined by the nature of the cationic charge +24.7 mV incorporated, nanosize around 86.95 and 91.22 nm, and efficiency loaded with the gene more than 95%. As well, the synthesized nanohydrogel exhibited a sharp volume-phase transition in water at a LCST of ∼40 °C. So, the combination of both monomers yielded an interesting system with high transfection efficiency and compliant biocompatibility characteristics, which could effectively achieve gene loading. Also, the magnetic potential of nanohydrogel was determined as a vector to deliver genes to localized sites. Notably, the synthesized combination P[NIPAM-DMAEMAQ] nanohydrogel has been considered a transfection of the biodegradable and biocompatible magnetic nanoparticle sensitive to tunable pH and temperature responsiveness, demonstrating that it will hold a promising approach as a potential carrier to improve gene delivery therapeutic efficacy in cancer and different disease treatments.

Hybrid Bonding Bottlebrush Polymers Grafted from a Supramolecular Polymer Backbone.

Bottlebrush polymers, macromolecules consisting of dense polymer side chains grafted from a central polymer backbone, have unique properties resulting from this well-defined molecular architecture. With the advent of controlled radical polymerization techniques, access to these architectures has become more readily available. However, synthetic challenges remain, including the need for intermediate purification, the use of toxic solvents, and challenges with achieving long bottlebrush architectures due to backbone entanglements. Herein, we report hybrid bonding bottlebrush polymers (systems integrating covalent and noncovalent bonding of structural units) consisting of poly(sodium 4-styrenesulfonate) (p(NaSS)) brushes grafted from a peptide amphiphile (PA) supramolecular polymer backbone. This was achieved using photoinitiated electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization in water. The structure of the hybrid bonding bottlebrush architecture was characterized using cryogenic transmission electron microscopy, and its properties were probed using rheological measurements. We observed that hybrid bonding bottlebrush polymers were able to organize into block architectures containing domains with high brush grafting density and others with no observable brushes. This finding is possibly a result of dynamic behavior unique to supramolecular polymer backbones, enabling molecular exchange or translational diffusion of monomers along the length of the assemblies. The hybrid bottlebrush polymers exhibited higher solution viscosity at moderate shear, protected supramolecular polymer backbones from disassembly at high shear, and supported self-healing capabilities, depending on grafting densities. Our results demonstrate an opportunity for novel properties in easily synthesized bottlebrush polymer architectures built with supramolecular polymers that might be useful in biomedical applications or for aqueous lubrication.

Design, Preparation, and Interfacial Adhesion of Polystyrene‐Based Luminophore Elastomers Based on Bionic Strategy

AbstractA series of rigid polystyrene‐based photoelastomers, named sty‐PM‐x, with bionic catechol pendants were synthesized through atom transfer radical polymerization (ATRP) and deprotection techniques. These polymers were characterized using nuclear magnetic resonance spectroscopy, gel permeation chromatography, and thermogravimetric analysis. Additionally, photophysical properties of the polymers were investigated using UV‐visible absorption spectroscopy and fluorescence emission spectroscopy. Mechanical properties were evaluated through tensile tests, while interfacial adhesion was determined through cross‐cut tests. Experimental results reveal that photoelastomers, sty‐PM‐x, exhibit excellent photophysical properties, stretchability, and interfacial adhesion. This discovery provides a new perspective for the preparation of stretchable organic electroluminescent materials.

Precision fabrication of polymer nanostructures on recyclable DNA template

AbstractThe fabrication of precisely patterned polymers at the nanoscale is of critical importance. We have previously succeeded in creating various nanopatterned polymers with nanoscale resolution through the use of in situ atom transfer radical polymerization (ATRP) techniques on deoxyribonucleic acid (DNA) origami. However, separating nanopatterned polymers from the origami template without damaging the origami presents a significant challenge, thereby increasing costs and limiting the development of applications involving nanopatterned polymers. Here, we achieved spatially and temporally controlled release of DNA origami templates through photo‐regulation by incorporating azobenzene‐modified DNA into the initiator. Under UV exposure, azobenzene isomerization rapidly induces the disassociation of patterned polymers from the origami template at ambient temperatures, without damaging the DNA origami. Additionally, the released origami template can be reused as a template for the cyclic production of nanopatterned polymers. This method provides a pathway for the large‐scale production of patterned polymers at reduced costs and facilitates dynamic control over the polymer‐DNA complex, with potential applications in both the biomedical and chemical fields.

Enhancing photothermal depolymerization with metalloporphyrin catalyst

AbstractThe ability to revert polymers to their original monomers represents a crucial chemical recycling technique, promoting sustainability and offering the chance to convert used materials into valuable products. In recent years, numerous studies have explored the use of polymers synthesized via reversible deactivation radical polymerization (RDRP) techniques to facilitate efficient depolymerization reactions. Herein, we report the use of a photocatalyst, zinc tetraphenylporphyrin (ZnTPP), along with light irradiation to accelerate depolymerization of polymers prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization. We explore various parameters affecting depolymerization efficiency, including solvents, reaction temperature (80, 100, and 120°C), the presence of photocatalysts (ZnTPP and Eosin Y), and the type of RAFT end‐groups, namely trithiocarbonate, dithiobenzoate, and 1H‐pyrazole‐1‐carbodithioate. For instance, when PMMA was diluted to 25 mM in 1,4‐dioxane and heated to 120°C under green light irradiation in the presence of ZnTPP (200 ppm), rapid depolymerization exceeding 70% occurred within 1 h. Without ZnTPP, under similar conditions, the reaction required over 8 h to achieve a slightly lower yield. Furthermore, this method confers moderate oxygen tolerance to the system, enabling depolymerization to proceed without the need of deoxygenation, albeit at a lower rate and consequently lesser monomer recovery (31%).

Controlled Magnetite Grafted Poly(glycidyl methacrylates) for Heavy Metal Absorption and Recovery via SET-LRP

A versatile magnetite based stringent polymer for effective metal capture was prepared by reacting iron oxide based initiator with glycidyl methacrylate monomer via single-electron transfer living radical polymerization (SET-LRP) technique. The versatile grafted polymer was successfully synthesized by metal catalyzed living radical polymerization using the catalyst system Cu/N,N,N',N'',N'''-pentamethyldiethylenetriamine as the ligand. The structural confirmation of the initiator and the grafted polymer was analyzed by using instrumentation methods such as proton nuclear magnetic resonance spectroscopy, UV-visible, TGA, SEM and gel permeation chromatography for molecular weight measurements. As the polymerization time increased, both the conversion and the molecular weight were observed to increase linearly with time. Narrow dispersed lower polydispersity index (PDI) and dispensable magnetite-g-PGMA was utilized for the extract of toxic lead from the wastewater. Sustained binding was observed due to the presence of epoxide ring in the repeating units of the polymer and recovered by magnetic effect. The material shows good stability as evident by TGA curves and better affinity to toxic lead as observed by UV-visible and SEM techniques.

Development and evaluation of a pH-responsive Mimosa pudica seed mucilage/β- cyclodextrin-co-poly(methacrylate) hydrogel for controlled drug delivery: In vitro and in vivo assessment

In this comprehensive investigation, a novel pH-responsive hydrogel system comprising mimosa seed mucilage (MSM), β-cyclodextrin (β-CD), and methacrylic acid (MAA) was developed via free radical polymerization technique to promote controlled drug delivery. The hydrogel synthesis involved strategic variations in polymer, monomer, and crosslinker content in fine-tuning its drug-release properties. The resultant hydrogel exhibited remarkable pH sensitivity, selectively liberating the model drug (Capecitabine = CAP) under basic conditions while significantly reducing release in an acidic environment. Morphological, thermal, and structural analyses proved that CAP has a porous texture, high stability, and an amorphous nature. In vitro drug release experiments showcased a sustained and controlled release profile. Optimum release (85.33 %) results were recorded over 24 h at pH 7.4 in the case of MMB9. Pharmacokinetic evaluation in healthy male rabbits confirmed bioavailability enhancement and sustained release capabilities. Furthermore, rigorous toxicity evaluations and histopathological analyses ensured the safety and biocompatibility of the hydrogel. This pH-triggered drug delivery system can be a promising carrier system for drugs involving frequent administrations.

Using RAFT Polymerization Methodologies to Create Branched and Nanogel-Type Copolymers.

This review aims to highlight the most recent advances in the field of the synthesis of branched copolymers and nanogels using reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerization is a reversible deactivation radical polymerization technique (RDRP) that has gained tremendous attention due to its versatility, compatibility with a plethora of functional monomers, and mild polymerization conditions. These parameters lead to final polymers with good control over the molar mass and narrow molar mass distributions. Branched polymers can be defined as the incorporation of secondary polymer chains to a primary backbone, resulting in a wide range of complex macromolecular architectures, like star-shaped, graft, and hyperbranched polymers and nanogels. These subcategories will be discussed in detail in this review in terms of synthesis routes and properties, mainly in solutions.

Formulation and In Vitro Assessment of Polymeric pH-Responsive Nanogels of Chitosan for Sustained Delivery of Madecassoside.

Madecassoside, a triterpenoid saponin compound mainly isolated from the gotu kola herb (Centella asiatica), shows an extensive range of biological activities, including antiapoptotic, antioxidant, anti-inflammatory, moisturizing, neuroprotective, and wound healing effects. It has been highly used in the management of eczema, skin wounds, and other diseases. Due to poor oral bioavailability, membrane permeability, and intestinal absorption, the clinical application of the madecassoside is limited. Hence, a drug carrier system is needed that not only sustains the release of the madecassoside but also overcomes the drawbacks associated with its administration. Therefore, the authors prepared novel pH-responsive chitosan-based nanogels for the sustained release of madecassoside. Free radical polymerization technique was used for cross-linking of polymer chitosan and monomer methacrylic acid in the presence of cross-linker N',N'-methylene bis(acrylamide). The decrease in polymer crystallinity after polymerization and development of nanogels was demonstrated by XRD and FTIR analysis. The effects of nanogel contents on polymer volume, sol-gel analysis, swelling, drug loading, and release were investigated. Results indicated that high swelling and maximum release of the drug occurred at pH 7.4 compared to pH 1.2 and 4.6, indicating the excellent pH-sensitive nature of the engineered nanogels. High swelling and drug release were perceived with the integration of a high quantity of chitosan, while a decline was observed with the high integration of N',N'-methylene bis(acrylamide) and methacrylic acid contents. The same effects of nanogel contents were shown for drug loading too. Sol fraction was reduced, while gel fraction was enhanced by increasing the chitosan load, N',N'-methylene bis(acrylamide), and methacrylic acid. The Korsmeyer-Peppas model of kinetics was trailed by all nanogel formulations with non-Fickian diffusion. The results demonstrated that prepared nanogels can be employed for sustained release of the madecassoside.

A Novel Approach of Polyvinyl Alcohol/Acrylic Acid Based Hydrogels for Controlled Delivery of Diclofenac Sodium.

The aim of this study was to prepare polyvinyl alcohol/acrylic acid (PVA/AA) hydrogels for the controlled release of diclofenac sodium and to develop PVA/AA hydrogels as controlled release carriers to overcome not only the side effects of diclofenac sodium but also sustain its release for an extended period. Diclofenac sodium is employed for relieving pain and fever. The half-life of diclofenac sodium is very short (1-2 h). Hence, multiple intakes of diclofenac sodium are required to maintain a constant pharmacological action. Multiple GI adverse effects are produced as a result of diclofenac sodium intake. A free radical polymerization technique was used for crosslinking PVA with AA in the presence of APS. EGDMA was used as a cross-linker. FTIR and XRD confirmed the preparation and loading of the drug by prepared hydrogels. An increase in the thermal stability of PVA was shown by TGA and DSC analysis. Surface morphology was investigated by SEM. Similarly, water penetration and drug loading were demonstrated by porosity and drug loading studies. The pH-sensitive nature of PVA/AA hydrogels was investigated at different pH values by swelling and drug release studies. The development and drug loading of PVA/AA hydrogels were confirmed by FTIR and XRD analysis. TGA and DSC indicated high thermal stability of prepared hydrogels as compared to unreacted PVA. SEM indicated a hard and compact network of developed hydrogels. The swelling and drug release studies indicated maximum swelling and drug release at high pH as compared to low pH values, indicating the pH-sensitive nature of prepared hydrogels. Moreover, we demonstrated that drug release was sustained for a prolonged time in a controlled pattern by prepared hydrogels by comparing the drug release of the developed hydrogels with the commercial product Cataflam. The results indicated that prepared PVA/AA hydrogels can be used as an alternative approach for the controlled delivery of diclofenac sodium.

Starch-Grafted Polyacrylic Acid Copolymer with Acrylamide: An Advanced Adsorbent for Victoria Green B Dye Removal and Environmental Remediation

A new adsorbent, starch grafted polyacrylic acid copolymer with polyacrylamide (SG@AA-co-AM), was synthesized using free radical polymerization techniques. Proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared spectrophotometry (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), particle size distribution (PSD), and fluorescent electron microscopy (FEM) were employed to elucidate the structure, crystalline nature, thermal stability, and surface morphology of SG@AA-co-AM. SG@AA-co-AM was utilized as an adsorbent for the removal of Victoria green B (VGB) dye from wastewater. SG@AA-co-AM exhibited a removal percentage (% R) of 97.6% towards VGB under optimized conditions: a contact time of 30 min, temperature of 25 °C, adsorbent dose of 20 mg, pH of 8, concentration of dye solution of 20 ppm, and volume of dye solution of 30 mL. The point of zero charge (PZC) for SG@AA-co-AM was determined to be 5.2. Nonlinear pseudo-second-order (PSO) and Langmuir adsorption isotherm models best fitted to the experimental data, with regression coefficients (R2) of 0.95 and 0.99, respectively. The results confirmed the chemi-sorption and monolayer adsorption of VGB onto SG@AA-co-AM. Thermodynamic studies revealed that the adsorption of VGB onto SG@AA-co-AM is endothermic and spontaneous. Furthermore, the regeneration experiment showed a decline of 3.9% after five cycles, confirming the economical and reusable nature of SG@AA-co-AM.

Progress in photocontrolled radical polymerization for the synthesis of nonlinear polymer architectures

AbstractControlled radical polymerization (CRP) techniques enable the preparation of diverse, chemically tailored polymers with a variety of chain architectures. Separately, light‐mediated polymerization reactions offer a number of advantages over thermal polymerizations in terms of energy efficiency, sustainability, and versatility. Recent work has combined photopolymerization and CRP techniques to advance the synthesis of polymers with nonlinear architectures, including bottlebrush polymers, star polymers, hyperbranched polymers, and cyclic polymers. These photoCRP methods offer novel routes to nonlinear polymers using mild reaction conditions. In this review, we provide an overview of photoCRP techniques for the synthesis of nonlinear polymers. We start with a discussion of photoCRP applied to the synthesis of linear polymers and discuss the underlying reaction mechanisms. Then, we discuss photoCRP applied to the synthesis of bottlebrush, star, hyperbranched, cyclic, and surface‐initiated polymer brushes. For each case, we discuss the synthetic strategy and the unique properties and characteristics of the resulting polymers, and we provide a perspective on potential future directions for research.