New polymeric architectures with (meth)acrylic acid segments

The Effect of Macromonomer Surfactant Microstructure on Aqueous Polymer Dispersion and Derived Polymer Film Properties

Water-borne coatings were prepared from poly(methyl methacrylate-co-butyl acrylate) latexes using different methacrylic acid containing macromonomers as stabilizers, and their physical properties were determined. The amphiphilic methacrylic acid macromonomers containing methyl, butyl, or lauryl methacrylate as hydrophobic comonomers were synthesized via catalytic chain transfer polymerization to give stabilizers with varying architecture, composition, and molar mass. A range of latexes of virtually the same composition was prepared by keeping the content of methacrylic acid groups during the emulsion polymerization constant and by only varying the microstructure of the macromonomers. These latexes displayed a range of rheological behaviors: from highly viscous and shear thinning to low viscous and Newtonian. The contact angles of the resulting coatings ranged from very hydrophilic (<10°) to almost hydrophobic (88°), and differences in hardness, roughness, and water vapor sorption and permeability were found.

Heterogeneous Brønsted Catalysis in the Solvent-Free and Multigram-Scale Synthesis of Polyalcohol Acrylates: The Case Study of Trimethylolpropane Triacrylate

This article presents a thorough investigation into the synthesis of trimethylolpropane triacrylate (TMPTA) via the esterification reaction of trimethylolpropane (TMP) with acrylic acid using Amberlite™ 120 IR (H+), Amberlyst® 15, and Dowex™ 50WX8 resins as heterogeneous catalysts. Preliminary comparative tests explored the impact of air flow on water removal during the reaction and different acid-to-alcohol molar ratios (3:1, 6:1, or 9:1 mol:mol). The findings revealed that introducing air significantly enhances TMPTA yield and -OH group conversion, particularly at a 6:1 acid-to-alcohol molar ratio. Based on cost considerations, Amberlite™ 120 IR (H+) was selected as the preferred catalyst for further optimization. This included evaluating the effect of catalyst loading (10%, 5.0%, and 2.5% w/wtot) and assessing the impact of a pre-drying process on resin efficiency. The study concluded that optimal conditions did not necessitate drying, requiring 120 °C, a catalyst loading of 10% w/wtot, a 4 h reaction time, an acid:alcohol ratio of 6:1 mol:mol, the presence of MEHQ (0.1% mol/molAA), and air bubbling at 6 ± 1 Nl/h. Catalyst recycling was effectively implemented with a slight reduction in catalytic activity over consecutive runs. Furthermore, the study explored a scaled-up system with a mechanical stirrer, demonstrating the potential for multi-hundred grams scale-up. Considerations for optimizing the air flow stripping system are also highlighted. In summary, this study provides valuable insights into designing and optimizing the esterification process for TMPTA synthesis, laying the foundation for potential industrial applications.

Design, Synthesis, and Spectral Properties of Novel 2-Mercaptobenzothiazole Derivatives

This paper is focused on the optimalization of methods for the synthesis, isolation, and purification of 2-mercaptobenzothiazole-based acrylic and methacrylic monomers. The structures of the newly synthesized compounds were confirmed through infrared (IR) and nuclear magnetic resonance spectroscopy (NMR). Spectroscopic properties of the resulting 2-mercaptobenzothiazole derivatives were determined based on their absorption spectra and molar absorption coefficients in solvents with varying polarities. A correlation was established between the calculated density functional theory (DFT) energies and Frontier Molecular Orbitals and the experimental observations, confirming their consistency. The practical utility of the synthesized compounds, particularly in future polymerization processes, hinges on a thorough understanding of these properties.

Copolymeric Micelles of Poly(ε-caprolactone) and Poly(methacrylic acid) as Carriers for the Oral Delivery of Resveratrol

In this study, we report the development of a micellar system based on a poly(methacrylic acid)-b-poly(ε-caprolactone)-b-poly(methacrylic acid) triblock copolymer (PMAA16-b-PCL35-b-PMAA16) for the oral delivery of resveratrol. The micellar nanocarriers were designed to comprise a PCL core for solubilizing the poorly water-soluble drug and a hydrated PMAA corona with bioadhesive properties for providing better contact with the gastrointestinal mucosa. The micelles were first formed in an aqueous media via the solvent evaporation method and then loaded with resveratrol (72% encapsulation efficiency). Studies by transmission electron microscopy (TEM) and dynamic and electrophoretic light scattering (DLS and PALS) revealed a spherical shape, nanoscopic size (100 nm) and a negative surface charge (-30 mV) of the nanocarriers. Loading of the drug slightly decreased the hydrodynamic diameter (Dh) and increased the ƺ-potential of micelles. In vitro dissolution tests showed that 80% and 100% of resveratrol were released in 24 h in buffers with pH 1.2 and 6.8, respectively, whereas for the same time, not more than 10% of pure resveratrol was dissolved. A heat-induced albumin denaturation assay demonstrated the advantage of the aqueous micellar formulation of resveratrol, which possessed anti-inflammatory potential as high as that of the pure drug. Further, the micellar resveratrol (5 µM) exerted a strong protective effect and maintained viability of mucosa epithelial HT-29 cells in a co-cultural model, representing the production of inflammatory cytokines. For comparison, the pure resveratrol at the same concentration did not protect the damaged HT-29 cells at all. Thus, the present study revealed that the PMAA-b-PCL-b-PMAA copolymeric micelles might be considered appropriate nanocarriers for the oral delivery of resveratrol.

Redox Polyelectrolytes with pH-Sensitive Electroactive Functionality in Aqueous Media

A framework of ferrocene-containing polymers bearing adjustable pH- and redox-active properties in aqueous electrolyte environments was developed. The electroactive metallopolymers were designed to possess enhanced hydrophilicity compared to the vinylferrocene (VFc) homopolymer, poly(vinylferrocene) (PVFc), by virtue of the comonomer incorporated into the macromolecule, and could also be prepared as conductive nanoporous carbon nanotube (CNT) composites that offered a variety of different redox potentials spanning a ca. 300 mV range. The presence of charged non-redox-active moieties such as methacrylate (MA) in the polymeric structure endowed it with acid dissociation properties that interacted synergistically with the redox activity of the ferrocene moieties to impart pH-dependent electrochemical behavior to the overall polymer, which was subsequently studied and compared to several Nernstian relationships in both homogeneous and heterogeneous configurations. This zwitterionic characteristic was leveraged for the enhanced electrochemical separation of several transition metal oxyanions using a P(VFc_0.63-co-MA_0.37)-CNT polyelectrolyte electrode, which yielded an almost twofold preference for chromium as hydrogen chromate versus its chromate form, and also exemplified the electrochemically mediated and innately reversible nature of the separation process through the capture and release of vanadium oxyanions. These investigations into pH-sensitive redox-active materials provide insight for future developments in stimuli-responsive molecular recognition, with extendibility to areas such as electrochemical sensing and selective separation for water purification.

Fabrication and Phase Behavior of Thermo- and/or pH-Responsive Polymer-Grafted SiO2 Nanoparticles

Three series of thermo- and/or pH-responsive polymer-grafted SiO2 nanoparticles, SiO2-graft-poly(oligo(ethylene glycol) methacrylate) (SiO2-g-POEGMA), SiO2-graft-poly(acrylic acid) (SiO2-g-PAA) and SiO2-graft-poly(oligo(ethylene glycol) methacrylate-state-acrylic acid (SiO2-g-P(OEGMA-stat-AA)), were prepared by grafting POEGMA and/or PAA onto the surface of silica nanoparticles through the surface-initiated atom transfer radical polymerization (SI-ATRP). The lower critical solution temperature (LCST) of SiO2-g-POEGMA (MOEGMA = 300 g/mol) was found to be 64 °C. For SiO2-g-PAA nanoparticles, at the pH range from 8 to 12, the hydrodynamic diameter of the nanoparticles increases with increasing pH, and the zeta potential of SiO2-g-PAA nanoparticles is negatively charged and decreases with increasing pH. Owing to the thermo- and pH-responsive, the hydrodynamic diameters of SiO2-g-P(OEGMA-stat-AA) nanoparticles increase with the increasing pH, and the LCSTs of those nanoparticles increase with the increase of POEGMA content.

Physical Characterization and Biodistribution of Cisplatin Loaded in Surfactant Modified-Hybrid Nanoparticles Using Polyethylene Oxide-b-Polymethacrylic Acid

Purpose: Conjugating cisplatin into hybrid nanoparticles is intended to enhance tumor accumulation in cancer therapy due to drug interaction with polymer and prevent premature drug release because of the presence of a lipid layer.

Methods: Hybrid nanoparticles composed of polyethylene oxide-b-polymethacrylic acid, egg phosphatidylcholine, and surfactant, i.e. sodium cholate/sodium deoxycholate/Tween 80, were prepared by the injection method. Cisplatin was subsequently loaded by incubating the polymer-drug mixtures at the molar ratio of carboxylate ions of 2:1.

Results: The results showed that the addition of surfactants produced particle sizes between 33 and 52 nm. The addition of cisplatin increased the ζ-potential to slightly positive charges with encapsulation efficiencies of 5%-18%. An in vivo biodistribution study of mice identified a cisplatin plasma concentration of sodium cholate-modified hybrid nanoparticles 10 times higher than cisplatin solution, thus producing high tumor accumulation.

Conclusion: Conjugating cisplatin into sodium cholate-modified hybrid nanoparticles improves its accumulation in tumors.

Shape-Changing Bottlebrush Polymers

Bottlebrush polymers (BBPs), composed of relatively short polymeric side chains densely grafted on a polymer backbone, exhibit many unique characteristics and hold promise for a variety of applications. This Perspective focuses on environmentally induced shape-changing behavior of BBPs at interface and in solution, particularly worm/star-globule shape transitions. While BBPs with a single type of homopolymer or random copolymer side chains have been shown to undergo pronounced worm-to-globule shape changes in response to external stimuli, the collapsed brushes are unstable and prone to aggregation. By introducing a second, solvophilic polymer into the side chains, either as a distinct type of side chain or as the outer block of block copolymer side chains, the collapsed brushes not only are stabilized but also create unimolecular micellar nanostructures, which can be used for, e.g., encapsulation and delivery of substances. The current challenges in the design, synthesis, and characterization of stimuli-responsive shape-changing BBPs are discussed.

Effect of nitrogen type on carbon dot photocatalysts for visible-light-induced atom transfer radical polymerization

N-Doping significantly enhanced the photo-activity of carbon dots. But only pyridinic N can improved the activity of CDs as catalysts for photo-induced ATRP, compared with pyrrolic N and graphitic N.

Water Interactions in Hybrid Polyacrylate-Silicate Hydrogel Systems

Hybrid polyacrylate-silicate hydrogels were obtained in the presence of N,N'-methylenebisacrylamide (NNMBA) as the cross-linking monomer and sodium thiosulphate/potassium persulphate (NTS/KPS) as the redox initiators. The results of the tests allowed us to conclude that a hybrid structure with a polyacrylate scaffolding and a silicate matrix had been obtained. The results of the rheological analysis revealed that the hydrogel sample with a 1:7 mass ratio of sodium water glass to the sodium polyacrylate is characterized by the highest complex viscosity. Thermal analysis (Thermogravimetry/Differential Scanning Calorimetry (TG/DSC)) showed that water begins to evaporate at higher temperatures, from 120 °C to even 180 °C. These results were confirmed by mid-infrared spectroscopy (MIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. Differences in the intensity of the peaks derived from water in the MIR spectra indicate that most of the water is bounded. In turn, NMR results showed that the mobility of water molecules decreases as the amount of sodium water glass in the mixture increases.

Atom Transfer Radical Polymerization of Acrylic and Methacrylic Acids: Preparation of Acidic Polymers with Various Architectures

The preparation of poly(acrylic acid) (PAA) with tailored architecture and morphology is important for the design of advanced polymer materials. Cu-catalyzed atom transfer radical polymerization (ATRP) of AA is challenging due to the tendency of dormant chains to undergo an intramolecular lactonization reaction with consequent loss of chain-end functionalities, as previously reported for ATRP of methacrylic acid (MAA). In addition, AA can coordinate to the Cu catalyst. Moreover, the lower ATRP reactivity of AA relative to MAA enhances side reactions during polymerizations. These issues were overcome by adjusting the composition of the catalytic system, the polymerization setup, and the initiator nature. AA conversion >70-80% was obtained in 5 h, producing PAA with Đ ≈1.4. Multifunctional water-soluble initiators provided PAA and PMAA with telechelic and star-shaped architectures. Block copolymers of MAA and AA confirmed the retention of chain-end functionalities during ATRPs.

Enhanced Heat Resistance and Adhesive Strength of Styrene-Acrylic Triblock Copolymer Elastomers by Incorporating Acrylic Acid

Herein, we present an industrially applicable strategy to enhance the heat resistance and adhesive properties of ABA triblock copolymer-based elastomers composed of styrene (St) and n-butyl acrylate (nBA) by incorporating acrylic acid (AA) at different segments. Three types of triblock copolymers, namely, poly(St-r-AA)-b-poly(nBA)-b-poly(St-r-AA), poly(St)-b-poly(nBA-r-AA)-b-poly(St), and poly(St)-b-poly(nBA)-b-poly(St), were synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Large-scale RAFT polymerization afforded industrially applicable AA-containing triblock copolymers with moderate molecular weights and predetermined comonomer compositions (St/nBA/AA = 15/83/2-24/73/3, number-average molecular weight (M n) = 30,000-110,000, and resulting product > 200 g). The heat resistance and pressure-sensitive adhesive properties of the triblock copolymers were evaluated. Among them, poly(St-r-AA)-b-poly(nBA)-b-poly(St-r-AA), having poly(nBA) as the middle soft segment and poly(St-r-AA) as hard segments at both ends, exhibited excellent heat creep resistance and increased adhesiveness to stainless steel. The feasibility to manipulate the heat resistance and adhesive properties by incorporating AA units into hard and soft segments, in addition to the ease of operation, high block efficiency, and metal-free nature owing to the RAFT process, is highly beneficial for practical applications of these copolymers.

Ionic Polymethacrylate Based Delivery Systems: Effect of Carrier Topology and Drug Loading

The presented drug delivery polymeric systems (DDS), i.e., conjugates and self-assemblies, based on grafted and star-shaped polymethacrylates have been studied for the last few years in our group. This minireview is focused on the relationship of polymer structure to drug conjugation/entrapment efficiency and release capability. Both graft and linear polymers containing trimethylammonium groups showed the ability to release the pharmaceutical anions by ionic exchange, but in aqueous solution they were also self-assembled into nanoparticles with encapsulated nonionic drugs. Star-shaped polymers functionalized with ionizable amine/carboxylic groups were investigated for drug conjugation via ketimine/amide linkers. However, only the conjugates of polybases were water-soluble, giving opportunity for release studies, whereas the self-assembling polyacidic stars were encapsulated with the model drugs. Depending on the type of drug loading in the polymer matrix, their release rates were ordered as follows: Physical ≥ ionic > covalent. The studies indicated that the well-defined ionic polymethacrylates, including poly(ionic liquid)s, are advantageous for designing macromolecular carriers due to the variety of structural parameters, which are efficient for tuning of drug loading and release behavior in respect to the specific drug interactions.

Shaping block copolymer micelles by supramolecular polymerization: making ‘tubisomes’

In contrast to the respective block copolymers, amphiphilic cyclic peptide conjugates self-assemble into cylindrical micelles independent of the polymer compositions.

Direct ATRP of Methacrylic Acid with Iron-Porphyrin Based Catalysts

An iron porphyrin catalyst, derived from the active center of proteins such as horseradish peroxidase and hemoglobin, was successfully used for the atom transfer radical polymerizations (ATRP) of methacrylic acid. ATRP of methacrylic acid and other acidic monomers is challenging due to Cu complexation by carboxylates, protonation of the ligand, and displacement of the halogen chain end. A robust mesohemin-based catalyst provided controlled ATRP of methacrylic acid, yielding poly(methacrylic acid) with Mn ≥ 20000 and dispersity Đ < 1.5. Retention of halogen chain end was confirmed by successful chain extension of a poly-(methacrylic acid)-Br macroinitiator.

Precise syntheses of structurally possible all tetrablock quaterpolymers by a methodology combining living anionic polymerization with linking chemistry using 1 : 1 addition reaction

A methodology combining living anionic polymerization with linking chemistry using 1 : 1 addition reaction has been developed for the syntheses of tetrablock quaterpolymers composed of A, B, C, and D blocks.

pH-Responsive, Amphiphilic Core-Shell Supramolecular Polymer Brushes from Cyclic Peptide-Polymer Conjugates

The synthesis and self-assembly of pH-responsive, amphiphilic cyclic peptide-polymer conjugates are described. The design relies on the introduction of a poly(2-(diisopropylamino)ethyl methacrylate) (pDPA) block between the cyclic peptide and a hydrophilic block. These conjugates are disassembled and protonated at low pH but assemble into core-shell nanotubes at physiological pH, as determined by a combination of titration experiments and scattering techniques.

Facile and sustainable functionalization of graphene layers with pyrrole compounds

A facile and sustainable functionalization of graphene layers was performed with pyrrole compounds (PyC) prepared through the Paal–Knorr reaction of a primary amine with 2,5-hexanedione. A good number of primary amines were used: hexanamine, dodecanamine, octadecanamine, 2-aminoacetic acid, 2-amino-1,3-propanediol, 3-(triethoxysilyl)propan-1-amine. The reactions were characterized by good yield, up to 96%, and indeed satisfactory atom efficiency, up to 80%. The functionalization of graphene layers was obtained by mixing PyC with a high surface area graphite and heating at a temperature range from 130°C to 150°C for 3 h. The yield of functionalization reaction was larger than 60% and also up to about 90% for the pyrrole compounds from dodecanamine and 2-amino-1,3-propanediol, respectively. The cycloaddition reaction between the graphene layers and the pyrrole compound, oxidized in two position, is proposed as working hypothesis to account for such efficient functionalization. Raman spectroscopy revealed that the structure of the graphitic substrate remained substantially unaltered, after the reaction. Stable dispersions of HSAG adducts with different PyC were prepared in solvents with different solubility parameters and HRTEM analysis showed the presence of aggregates of only few layers of graphene. Qualitative results of dispersion tests were used to calculate the Hansen sphere for the HSAG adduct with the pyrrole compound based on dodecanamine so to provide a first estimate of its Hansen solubility parameters. This work paves the way for the facile and sustainable modification of the solubility parameters of graphene layers and for the predictive assessment of their compatibility with different environments.

Recent development of functional aliphatic polycarbonates for the construction of amphiphilic polymers

Functional aliphatic polycarbonates in the construction of amphiphilic polymers are summarized in seven categories (hydrophobic, hydrophilic, or/and functional unit).

Aqueous solutions of random poly(methyl methacrylate-co-acrylic acid): effect of the acrylic acid content

.Effect of acrylic acid (AA) content on the bulk solution and air/water interfacial properties of PMMA–AA.

Tunable Length of Cyclic Peptide-Polymer Conjugate Self-Assemblies in Water

Polymers conjugated to cyclic peptides capable of forming strong hydrogen bonds can self-assemble into supramolecular bottlebrushes even in aqueous solutions. However, controlling the aggregation of these supramolecular assemblies remains an obstacle that is yet to be overcome. By introducing pH-responsive poly(dimethylamino ethyl methacrylate) (pDMAEMA) arms, the repulsive forces were tuned by adjusting the degree of protonation on the polymer arms. Neutron scattering experiments demonstrated that conjugates in an uncharged state will self-assemble into supramolecular bottlebrushes. Reducing the pH in the system led to a decrease in the number of aggregation, which was reversible by addition of base. Potentiometric titration showed a correlation between the number of aggregation and the degree of ionization of the pDMAEMA arms. Hence, a balance between the strength of the hydrogen bonds and the repulsive electrostatic interactions determines the number of aggregation and extent of self-assembly. The presented work demonstrates that conjugate self-association can be controlled by tuning the charge density on the conjugated polymer arms, paving the way for the use of responsive cyclic peptide conjugates in pharmaceutical applications.

Interactions of complex polymers with nanoporous substrate

With the advance of polymer synthesis, polymers that possess unique architectures such as stars or cyclic chains, and unique chemical composition distributions such as block copolymers or statistical copolymers have become frequently encountered. Characterization of these complex polymer systems drives the development of interactive chromatography where the adsorption of polymers on the porous substrate in chromatography columns is finely tuned. Liquid Chromatography at the Critical Condition (LCCC) in particular makes use of the existence of the Critical Adsorption Point (CAP) of polymers on solid surfaces and has been successfully applied to characterization of complex polymer systems. Interpretation and understanding of chromatography behaviour of complex polymers in interactive chromatography motivates theoretical/computational studies on the CAP of polymers and partitioning of these complex polymers near the CAP. This review article covers the theoretical questions encountered in chromatographic studies of complex polymers.

pH-Responsive nanocapsules from silylated copolymers

We introduce here a concept allowing the synthesis of smart nanocapsules without a surfactant.

Efficient synthesis of narrowly dispersed amphiphilic double-brush copolymers through the polymerization reaction of macromonomer micelle emulsifiers at the oil–water interface

Narrowly dispersed amphiphilic PMA-g-PMMA/PDMA DBCs with high molecular weight were efficiently synthesized by Pickering emulsion template directed radical polymerization of macromonomer micelles.

Synthesis and Biomedical Applications of Poly((meth)acrylic acid) Brushes

Poly((meth)acrylic acid) (P(M)AA) brushes possess a number of distinctive properties that are particularly attractive for biomedical applications. This minireview summarizes recent advances in the synthesis and biomedical applications of P(M)AA brushes and brushes containing P(M)AA segments. First, we review different surface-initiated polymerization (SIP) methods, with a focus on recent progress in the surface-initiated controlled/living radical polymerization (SI-CLRP) techniques used to generate P(M)AA brushes with a tailored structure. Next, we discuss biomolecule immobilization methods for P(M)AA brushes, including physical adsorption, covalent binding, and affinity interactions. Finally, typical biomedical applications of P(M)AA brushes are reviewed, and their performance is discussed based on their unique properties. We conclude that P(M)AA brushes are promising biomaterials, and more potential biomedical applications are expected to emerge with the further development of synthetic techniques and increased understanding of their interactions with biological systems.

Asymmetric block copolymers for supramolecular templating of inorganic nanospace materials

This review focuses on polymeric micelles consisting of asymmetric block copolymers as designed templates for several inorganic nanospace materials with a wide variety of compositions. The presence of chemically distinct domains of asymmetric triblock and diblock copolymers provide self-assemblies with more diverse morphological and functional features than those constructed by EOn POm EOn type symmetric triblock copolymers, thereby affording well-designed nanospace materials. This strategy can produce unprecedented nanospace materials, which are very difficult to prepare through other conventional organic templating approaches. Here, the recent development on the synthesis of inorganic nanospace materials are mainly focused on, such as hollow spheres, tubes, and porous oxides, using asymmetric triblock copolymers.