Preparation Of Copolymers Research Articles

Modular Synthesis of PEG-Dendritic Block Copolymers by Thermal Azide-Alkyne Cycloaddition with Internal Alkynes and Evaluation of their Self-Assembly for Drug Delivery Applications.

Linear-dendritic block copolymers assemble in solution due to differences in the solubility or charge properties of the blocks. The monodispersity and multivalency of the dendritic block provide unparalleled control for the design of drug delivery systems when incorporating poly(ethylene glycol) (PEG) as a linear block. An accelerated synthesis of PEG-dendritic block copolymers based on the click and green chemistry pillars is described. The tandem composed of the thermal azide-alkyne cycloaddition with internal alkynes and azide substitution is revealed as a flexible, reliable, atom-economical, and user-friendly strategy for the synthesis and functionalization of biodegradable (polyester) PEG-dendritic block copolymers. The high orthogonality of the sequence has been exploited for the preparation of heterolayered copolymers with terminal alkenes and alkynes, which are amenable for subsequent functionalization by thiol-ene and thiol-yne click reactions. Copolymers with tunable solubility and charge were so obtained for the preparation of various types of nanoassemblies with promising applications in drug delivery.

Self‐assembled polypeptoid micelles from amphiphilic polypeptoid copolymers for drug delivery

AbstractAmphiphilic block copolymers are characterized by the presence of distinct hydrophilic and hydrophobic regions, which are usually arranged in alternating blocks. This unique structure allows these copolymers to self‐assemble into well‐defined nanostructures that exhibit remarkable resistance to enzymatic hydrolysis, high biocompatibility and the ability to be customized with specific structures. These properties make them highly desirable in various applications. Self‐assembled amphiphilic polypeptoids are currently under development as a promising class of pharmaceutical agents. However, the utilization of these peptides as drug carriers for efficient delivery presents a number of challenges. These challenges include less‐than‐optimal loading efficacy and restricted biocompatibility. Herein, a series of stable amphiphilic block copolypeptoids (PNEG‐b‐PNBG and PNEG‐b‐PNHG) were designed and synthesized by controlled ring‐opening polymerization. PNEG chain segments provide hydrophilicity, while PNBG and PNHG chain segments provide hydrophobicity. The hydrophobic molecular chains aggregate in aqueous solutions, resulting in the formation of nano‐assemblies. The self‐assembled amphiphilic block polypeptoid copolymers were investigated. The morphologies of copolymers take the form of micelles from tens of nanometers to a few hundred nanometers. The properties of amphiphilic block copolypeptoids used as drug carriers were further investigated by conducting drug release and cytotoxicity tests. The results indicate that the cumulative release efficiency of self‐assembled polypeptoid copolymers can reach up to about 91%. And they have good biocompatibility and can be expected to be safe materials for efficient drug delivery. This work could provide a facile method for the preparation of amphiphilic block peptoid copolymers for biopharmaceutical applications. © 2024 Society of Industrial Chemistry.

Preparation of acrylate-cationic monomer block copolymers by RAFT and their flotation oil removal properties

With the development of oilfields, the liquid volume of oily wastewater gets larger. Thus, more efficient flotation agents must be developed. In this regard, cationic polyacrylates with amphiphilic structures are potentially efficient flotation agents. Many studies have explored the effect of monomer type on flotation performance. However, there is a lack of investigations on the effect of block sequences on flotation performance. In this paper, acrylates (including methyl acrylate (MA) and ethyl acrylate (EA)) and cationic monomers (including acryloxyethyl trimethyl ammonium chloride (DAC), methylacryloxyethyl trimethyl ammonium chloride (DMC) and acryloxyethyl benzyl dimethyl ammonium chloride (DBC)) were used as raw materials, random, diblock and triblock copolymers were prepared through free radical polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization. The effect of the copolymer sequence on flotation performance was studied, and triblock copolymer P(DBC-b-MA-b-DBC) had better flotation performance than those of other copolymers. The synthesis conditions of P(DBC-b-MA-b-DBC) were successively optimized using the single-factor and response surface methods, and the optimal synthesis conditions were obtained as follows: monomer concentration of 51 wt%, the first section m(DBC): the second section m(MA): the third section m(DBC) = 1.5:1:1.5, initiator concentration of 0.28 wt%, reaction time of each section of 2 h, and reaction temperature of 73 °C. Under flotation temperature of 25 °C, P(DBC-b-MA-b-DBC) concentration of 70 mg/L, aeration flow rate of 2.0 L/min and flotation time of 10 min, the oil removal of oily wastewater with initial oil content of 822 mg/L reached 96.5 %. The results of the study can provide reference for the research and development of oily wastewater treatment agents.

Preparation and characterization of isotactic polypropylene-based block copolymers with cyclic units

Olefin block copolymer is one class of promising high-end material that has the potential to combine the performance advantages of individual blocks. In this work, a series of isotactic polypropylene (iPP)-based diblock copolymers was designed and synthesized by coordinative chain transfer polymerization using a dimethyl(pyridylamido)hafnium/[Ph3C][B(C6F5)4]/AliBu3 catalytic system. The prepared diblock copolymers were composed of the regular iPP segments and the propylene/1,5-hexadiene (1,5-HD) random segments. The incorporated 1,5-HD existed exclusively as methylene-1,3-cyclopentane units in the polymer chains, because of the complete cyclization selectivity of the employed dimethyl(pyridylamido)hafnium catalyst. These block copolymers possessed high melting temperatures over 158 °C. Moreover, the block copolymers exhibited remarkably improved mechanical properties with respect to iPP, which could be systematically tuned by adjusting the content of 1,5-HD. In the 1,5-HD content range of 3.4–11.0 mol%, the block copolymers exhibited both high yield stress and high elongations at break. The copolymerization approach of block copolymers provided an effective method to achieve the strength-ductility balance of iPP-based copolymers.

Nonisocyanate Polyurethane Segmented Copolymers from Bis-Carbonylimidazolides.

Bis-carbonylimidazolide (BCI) functionalization enables an efficient synthetic strategy to generate high molecular weight segmented nonisocyanate polyurethanes (NIPUs). Melt phase polymerization of ED-2003 Jeffamine, 4,4'-methylenebis(cyclohexylamine), and a BCI monomer that mimics a 1,4-butanediol chain extender enables polyether NIPUs that contain varying concentrations of hard segments ranging from 40 to 80wt. %. Dynamic mechanical analysis and differential scanning calorimetry reveal thermal transitions for soft, hard, and mixed phases. Hard segment incorporations between 40 and 60wt. % display up to three distinct phases pertaining to the poly(ethylene glycol) (PEG) soft segment Tg , melting transition, and hard segment Tg , while higher hard segment concentrations prohibit soft segment crystallization, presumably due to restricted molecular mobility from the hard segment. Atomic force microscopy allows for visualization and size determination of nanophase-separated regimes, revealing a nanoscale rod-like assembly of HS. Small-angle X-ray scattering confirms nanophase separation within the NIPU, characterizing both nanoscale amorphous domains and varying degrees of crystallinity. These NIPUs, which are synthesized with BCI monomers, display expected phase separation that is comparable to isocyanate-derived analogues. This work demonstrates nanophase separation in BCI-derived NIPUs and the feasibility of this nonisocyanate synthetic pathway for the preparation of segmented PU copolymers.

Controllable preparation of PDMS-based copolymers with long-lasting high hydrophobicity for coating protection of summer cloth surfaces

Controllable preparation of PDMS-based copolymers with long-lasting high hydrophobicity for coating protection of summer cloth surfaces

A new method for synthesis of modified cellulose‐graft‐poly(acrylic acid) copolymer using 4‐cyano‐4‐[(phenylcarbothioyl)solfanyl]pentanoic acid to serve as RAFT agent

AbstractIn this study, cellulose was first treated with 4‐cyano‐4‐((phenyl carbonothioyl)solfanyl) pentanoic acid to serve as the reversible addition‐fragmentation chain transfer polymerization (RAFT) agent, then the controlled grafting polymerization of acrylic acid was successfully performed. A well‐defined, cellulose‐graft‐acrylic acid copolymer (Cell‐g‐PAA), has been prepared by RAFT polymerization technique using three different approaches: RAFT agent was prepared by substitution of dithiobenzoate magnesium bromide with 4,4'‐azobis(4‐cyanopentanoic acid) in ethyl acetate as a solvent, mediated cellulose (Cell) block as the macromolecular Cell‐RAFT agent and (cellulose‐co‐acrylic acid) copolymer with alternating sequence. The resulting (Cell‐RAFT) for “living” free radical polymerization was then heated in the adjacent acrylic acid monomer for the development of the controlled graft copolymer onto cellulose. The structures of the intermediate, graft copolymer were investigated by FT‐IR, DSC, 1H NMR, scanning electron microscopy, and thermo gravimetric. The results demonstrate that the preparation of graft copolymers was successfully confirmed. This approach would provide an extensive classification of molecular designs to obtain modern types of tailored hybrid materials derived from natural polysaccharides and synthetic polymers. Also, using a macro‐initiator is an excellent method for synthesizing new materials.

Nitric Oxide-Releasing Tubular Polymersomes toward Advanced Gas Therapeutic Carriers.

Nitric oxide (NO) not only plays a vital role in a series of physiological processes but also has great potential for therapeutic applications. One of the existing challenges in using NO as a gas therapeutic is the inconvenience of gaseous NO storage, and thus, it is of importance to develop NO-releasing vehicle platforms. Although a variety of polymer-based NO-releasing nanoparticles have been constructed, a majority of the systems are limited to spherical morphologies. Here we present the preparation of biodegradable NO-releasing amphiphilic block copolymers containing poly(ethylene glycol) (PEG) and poly(trimethylene carbonate-4-nitro-3-(trifluoromethyl)) (PTMC-NF), which can self-assemble into tubular polymersomes. The tubular polymersomes with high aspect ratio structures showed much faster NO-releasing behavior, in contrast to their spherical counterparts under light irradiation. We found that the amount of NO released from tubular polymersomes is 1.5 times that from spherical polymersomes. More importantly, the tubular polymersomes have an enhanced anticancer performance compared to spherical polymersomes, demonstrating that the morphology of the NO-releasing polymersomes has a significant effect on their anticancer ability. In view of the benefits of NO-releasing tubular polymersomes, we expect that they can be used as an efficient NO delivery system for enhanced gas therapy.

One stone two birds: from one azlactone-functionalized monomer to a heterofunctional diblock copolymer

An innovative combination of RAFT polymerization using easy-to-implement conditions and post-polymerization modification by click aminolysis for efficient preparation of heterofunctional diblock copolymers derived from vinyl azlactone.

Amide-Containing Bottlebrushes via Continuous-Flow Photoiniferter Reversible Addition-Fragmentation Chain Transfer Polymerization: Micellization Behavior.

Herein, a series of ternary amphiphilic amide-containing bottlebrushes were synthesized by photoiniferter (PI-RAFT) polymerization of macromonomers in continuous-flow mode using trithiocarbonate as a chain transfer agent. Visible light-mediated polymerization of macromonomers under mild conditions enabled the preparation of thermoresponsive copolymers with low dispersity and high yields in a very short time, which is not typical for the classical reversible addition-fragmentation chain transfer process. Methoxy oligo(ethylene glycol) methacrylate and alkoxy(C12-C14) oligo(ethylene glycol) methacrylate were used as the basic monomers providing amphiphilic and thermoresponsive properties. The study investigated how modifying comonomers, acrylamide (AAm), methacrylamide (MAAm), and N-methylacrylamide (-MeAAm) affect the features of bottlebrush micelle formation, their critical micelle concentration, and loading capacity for pyrene, a hydrophobic drug model. The results showed that the process is scalable and can produce tens of grams of pure copolymer per day. The unmodified copolymer formed unimolecular micelles at temperatures below the LCST in aqueous solutions, as revealed by DLS and SLS data. The incorporation of AAm, MAAm, and N-MeAAm units resulted in an increase in micelle aggregation numbers. The resulting bottlebrushes formed uni- or bimolecular micelles at extremely low concentrations. These micelles possess a high capacity for loading pyrene, making them a promising choice for targeted drug delivery.

Preparation and displacement performance of ternary copolymer (HAPEC)/graphene oxide composites

How to deal with high temperature and high salt reservoirs is a great challenge in the field of polymers. In this paper, a functional monomer (APEC) was homemade, copolymerized with acrylic acid and acrylamide to form a terpolymer, and solution blended with graphene oxide (GO) to prepare a terpolymer/graphene oxide composite (HAPEC/GO). The optimal ratio HAPEC/GO = 20:1 (GH20) was screened. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy (1H NMR), and electron microscopy (SEM). The temperature sensitivity, salt resistance, rheology, and aging resistance of GH20 were found to be superior to hydrolyzed polyacrylamide (HPAM), as evaluated by the apparent viscosity of the solution. When tested under simulated water conditions of 90 °C and 1.0 × 105 mg/L total mineralization, the GH20 solution demonstrated a further improvement in recovery, reaching 16.99 % compared to water flooding alone. The final recovery was 7.49 % higher than that of HPAM. The results demonstrate that the composite prepared can be effectively utilized in reservoirs with high temperature and high salt conditions, making it a promising method for enhanced oil recovery.

Preparation of block copolymer PS-b-PFPE and its application on cotton fabric electrostatic microsphere spraying

Preparation of block copolymer PS-b-PFPE and its application on cotton fabric electrostatic microsphere spraying

Chlorpyrifos and diazinon elimination through pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanoadsorbent hydrogel from wastewater: Preparation, characterization, kinetics and isotherm

In this study, a MOF-functionalized biopolymer nanoadsorbent hydrogel was developed to effectively eliminate chlorpyrifos (CPF) and diazinon (DZ) from aquatic areas. The adsorbent system was prepared through a multi-step process, such as graft copolymer preparation of xanthan gum (XG) with acrylamide (Aam) and cross-linking with N,N'-Methylenebisacrylamide (MBA) to obtain (pAAm-g-XG), synthesis of Fe3O4 MNPs through ex-situ co-precipitation method, and covalent attachment onto the pAAm-g-XG. Finally, in-situ HKUST-1 was attached to pAAm-g-XG@Fe3O4 to obtain the pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel. They are characterized by a variety of characteristic methods for example, FTIR, VSM, SEM, TGA, EDX, XRD, and BET confirmed the adequate preparation of pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel. CPF and DZ, both organophosphorus pesticides (OPPs), were studied for their removal from aqueous solutions using the developed adsorbent system. The most efficient adsorption conditions were achieved by doing batch adsorption tests with varying values of solution pH, adsorbent dose, contact duration, and beginning concentrations of CPF and DZ. Additionally, model fitting was excellent for the Freundlich isotherm model, and by using the pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel, the maximal adsorption capacity of DZ and CPF was achieved about 4525.102 and 1708.735 mg.g−1, consequently. The pseudo-second-order (PSO) model, according to the findings, is an excellent fit for the experimental data in this research on adsorption kinetics. The hypothesized process suggests that intermolecularly by hydrogen bonding, diffusion, and entrapment in the polymeric lattice of biopolymer nanocomposite hydrogel all contribute to the adsorption of CPF and DZ onto the biopolymer nanocomposite hydrogel. The two OPPs under study responded best to regeneration studies lasting up to four cycles.

Preparation of Block Copolymers by a Sequential Transesterification Strategy: A Feasible Route for Upcycling End-of-Life Polyester Plastics to Elastomers

Preparation of Block Copolymers by a Sequential Transesterification Strategy: A Feasible Route for Upcycling End-of-Life Polyester Plastics to Elastomers

Facile synthesis of asymmetric tetrablock copolymer by dual thermal and photochemical initiator

Vesicles obtained by the self-assembly of asymmetric tetrablock copolymers are a class of materials with fascinating properties. However, simple strategies to synthesize asymmetric tetrablock copolymers are limited. Herein, we have designed and synthesized an initiator which generates radicals by either heating or photoirradiation. Taking the advantages of organocatalyzed reversible complexation mediated radical polymerization which has lower energy requirements, milder reaction conditions, and reduced generation of hazardous byproducts, a three steps synthetic route following “photo-photo-thermal” initiation condition for the preparation of asymmetric CABC tetrablock copolymers with controllable molecular weight, precise block composition and low polydispersity was developed.

Facile preparation of diblock copolymers as functional surfaces for protein chromatography

AbstractStationary phase plays a crucial role in the operation of a protein chromatography column. Conventional resins composed of acrylic polymers and their derivatives contribute to heterogeneity of the packing of stationary phase inside these columns. Alternative polymer combinations through customized surface functionalization schemes which consist of multiple steps using static coating techniques are well known. In comparison, it is hypothesized that single‐step scheme is sufficient to obtain porous adsorbents as stationary phase for tuning surface morphology and protein immobilization. To overcome the challenge of heterogeneous packing and ease of fabrication at laboratory scale, change in the form factor of separation materials has been proposed in the form of functional copolymer surfaces. In the present work, an amphiphilic, block copolymer, poly(methyl methacrylate‐co‐methacrylic acid) has been chosen and fully characterized for its potential usage in protein chromatography. Hydrophilicity of the acrylic copolymer and abundance of carboxyl groups inherently on the copolymer surface have been successfully demonstrated through contact angle measurements, Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) studies. Morphological studies indicate presence of a microporous region (nearly 1.3 μm average pore size) that could be beneficial as a cation exchange media as part of the stationary phase in protein chromatography.

Preparation of copolymer brush‐type restricted access microspheres with adjustable adsorption selectivity to variety of dyes

AbstractRestricted access materials (RAMs) with adjustable selectivity was developed for the removal and detection of residual dyes for the solve problems of dye contamination. In this work, using homemade poly(4‐vinylbenzyl chloride‐co‐divinylbenzene) (PVBC/DVB) microspheres as substrate and successive two‐step surface‐initiated atom transfer radical polymerization (SI‐ATRP) as synthesis method, the two types of monomers, sodium 4‐vinylbenzene sulfonate (Nass) and styrene (St) were first grafted for constructing mixed interactions of adsorption sites, and then the hydrophilic glycidyl methacrylate (GMA) was polymerized, following by hydrolysis to construct diol groups on the external PVBC/DVB as the restricted access sites. The developed PVBC/DVB@poly(St‐co‐Nass)@poly(GMA) of adsorption properties was investigated by six dyes including methylene blue (MB), basic fuchsin (BF), acid fuchsin (AF), neutral red (NR), methyl orange (MO), and Congo red (CR), the adsorption capacities of those dyes and the removal rate for the binary mixed dye solution both rely on the ratio of St/Nass, confirming the adjustable adsorption selectivity. When PVBC/DVB@poly(St‐co‐Nass)@poly(GMA) was packed as solid phase extraction adsorbent in couple with UV–vis spectrum, it was applied to the determination of MB and BF in the water, fish and shrimp, good linearity with satisfactory recoveries for MB and BF are obtained to show the favorable practicability.

Synthesis, characterization, and optical properties of ROMP copolymers with pendant carbazole and coumarin groups

Two series of random copolymers containing at the same time two fluorescent groups, carbazole and coumarin, linked to a poly(norbornene dicarboximide) backbone have been prepared by controlled ring-opening metathesis polymerization (ROMP), promoted by Grubbs’ third generation catalyst (G3). The relative amount of the two functionalities was systematically varied along the copolymer chain, and the high degree of structural control observed allowed also for the preparation of a block copolymer with an equimolar content of fluorophore groups.In comparison to the related homopolymers, all the random copolymers exhibited in solution typical photoluminescence due to the carbazole or coumarin moiety, together with fluorescence arising from the energy transfer from the donor carbazole groups to the acceptor coumarin groups. This energy transfer seems to occur through intramolecular interactions, as it is not observed in the block copolymer and in the 50/50 homopolymer blend. On the other hand, in the solid state also the energy transfer from carbazole to coumarin through interchain interactions can take place. Of note, moving from solution to solid state fluorescence analysis, a blue shift of the band related to the energy transfer phenomenon is observed. This finding could be related to a combined effect of energy and electron transfer from donor to acceptor.

Preparation of nano-micron copolymers for polymer flooding using aqueous solution polymerization and inverse emulsion polymerization and their comparison

Oil displacing agents used in oil drilling and extraction can improve crude oil recovery. Acrylamide polymers were the most common oil displacing agents because of their high viscosity and low cost. However, conventional acrylamide polymers were susceptible to hydrolysis and thermal degradation in harsh reservoir conditions. Unique physical and chemical properties of nanoparticles promise to improve the performance of acrylamide polymers in harsh reservoir conditions. In this paper, the nano-micron copolymers of acrylamide (AM), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), and modified nano-silica (M-SiO2) were synthesized by two methods: aqueous solution polymerization and inverse emulsion polymerization, named W-PAAGS and E-PAAGS, respectively. The characterization was studied by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), particle size analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The thickening ability, temperature resistance, salt resistance, and thermal stability of the two polymers synthesized were studied. The results showed that E-PAAGS had a better thickening ability than W-PAAGS. The viscosity of the E-PAAGS solution was much higher than that of the W-PAAGS solution at polymer concentrations above 5000 mg/L. The temperature and salt resistance of E-PAAGS was also better than that of the W-PAAGS. In addition, E-PAAGS exhibits better aging stability. After 30 days of aging, E-PAAGS had 71.3% viscosity retention whereas only 52.7% retention was observed for W-PAAGS, and the viscosity of E-PAAGS was always higher than that of W-PAAGS. The significant difference properties of W-PAAGS and E-PAAGS was due to the differences in copolymer structure caused by the different polymerization methods.

Investigation of Curing Process and Thermal Behavior of Copolymers Based on Polypropylene Glycol Fumarate and Acrylic Acid Using the Methods of DSC and TGA.

In this work, the possibility of preparation of copolymers of three-dimensional crosslinked structure based on polypropylene glycol fumarate and acrylic acid is shown. The initial reagent polypropylene glycol fumarate has been synthesized by polycondensation reaction of fumaric acid and propylene glycol. The curing process of polypropylene glycol fumarate and acrylic acid at various mole concentrations was studied using DSC method at isothermal and dynamic regimens. Curing in isothermal condition was carried out at temperatures of 60 °C, 70 °C, and 80 °C. Residual reactivity was evaluated at a dynamic regimen within the temperature range from 30 °C to 200 °C at a constant heating rate. On the basis of calorimetric studies, the thermal effects and kinetic parameters of the reaction (conversion, reaction rate, activation energy) have been determined. Thermal behavior of cured samples of p-PGF-AA was estimated using dynamic thermogravimetry (TGA). According to TGA data, the process of decomposition of the studied copolymers proceeds in several stages. Based on the results obtained, the activation energies of thermal decomposition were calculated using the iso-conversional methods of Kissinger-Akakhira-Sunose and Friedman.