Spin probe EPR spectroscopy was used to investigate the polymer chain collapse in aqueous solutions of poly(N-isopropylacrylamide) (PNIPA) and its block copolymers with polyethylene glycol (PEG). The research demonstrated that for polymers with relatively low molecular weight, the polymer end groups and presence of comonomers significantly broaden the temperature interval of chain collapse. Inhomogeneities formed during the collapse process possess local polarity close to that in chloroform. Dynamic exchange of the probe molecules between inhomogeneities and bulk solution is observed for all the polymers studied.

The peroxyoxalate chemiluminescent reaction (PO-CL reaction) is particularly significant among energy sources for chemiexcited photodynamic therapy, owing to its high quantum yield. Nevertheless, when conducted in an aqueous medium, PO-CL reaction often encounters side reactions, such as oxalate hydrolysis, which considerably diminish the quantum yield. To mitigate the impact of side processes, hydrophobic nanoreactors are utilized. Our research represents the first investigation of the relationship between the polarity of micellar nanoreactors and the kinetics and efficiency of PO-CL reaction. Block copolymers composed of monomethoxy-poly(ethylene glycol), mPEG, and poly(L-lactide) (PLLA) or poly(epsilon-caprolactone) (PCL) were synthesized and used for preparation of micellar nanoreactors. Micelle polarity estimated by the position of the absorption band ET30 was recognized to be an important factor determining performance of PO-CL reaction. A decrease in nanoreactor polarity caused a reduction of hydrolysis rate constant and a growth of the efficiency of PO-CL reaction. The latter effect appeared to be due to the enhancement of the efficiency of activator excitation step of PO-CL reaction. The results obtained herein open the way to rational design of functioning nanoreactors for chemiexcited-PDT.

Branched polymers offer highly tunable properties and functionality. However, obtaining soluble, sufficiently branched macromolecules within the desired molecular weight range by conventional radical polymerization (RP) is still a challenging task, as there is no systematic investigation of this problem. In this work, we develop a three-dimensional coarse-grained molecular-dynamics model of RP in the presence of a divinyl crosslinker (CL) and a chain-transfer agent (CTA). Simulations are based on the Kremer-Grest bead-spring framework with Langevin dynamics under good-solvent conditions and include stochastic reactions: initiation, propagation, crosslinking, chain transfer, and termination. Macromolecular architecture is quantified by graph-based decomposition into dangling ends, elastically active subchains, and cycles, and by extracting an effective fractal dimension from the scaling of the radius of gyration with molecular mass. Two distinct regimes emerge. At low CTA content, gelation occurs at relatively small conversion; a rapidly growing network quickly dominates the molecular-weight distribution, which broadens substantially, while the population of isolated branched macromolecules diminishes. Increasing the CTA content shifts gelation toward high conversion, enabling the formation of a stable sol fraction enriched in high-molecular-weight branched molecules. Phase diagrams over 2%-16% crosslinker and 0%-8% CTA identify a simple optimal condition: the gel-point conversion approaches unity along [CL] = 2[CTA], consistent with an average of two effective intermolecular attachment points per growing chain. Along this optimum line, higher crosslinker content produces more compact branched macromolecules, implying higher coil-overlap concentrations and lower intrinsic viscosities at fixed molecular weight. These results provide practical, quantitative guidance for selecting reagent ratios to synthesize soluble branched polymers via standard RP.

Nanogels are promising responsive materials for biomedical and environmental applications due to their unique combination of high surface area, controlled cargo release, and sensitivity to external stimuli. Among them, thermosensitive systems based on poly(N-isopropylacrylamide) (PNIPAM) are particularly valuable, as their phase transition temperature (∼32 °C) is close to physiological conditions. This study reports the synthesis of unusually small nanogels via copolymerization of N-isopropylacrylamide (NIPAM) with the anionic monomer sodium styrene sulfonate (SSNa) in the range of 2–10 mol%. We explore in detail the copolymerization mechanism of these monomers. We investigate how the SSNa content affects the stability, size, and thermosensitive properties of the resulting particles. It is demonstrated that up to 10 mol% of SSNa can be incorporated without disrupting the phase-separation ability of PNIPAM above 32 °C. The presence of SSNa groups enables electrostatic binding of oppositely charged species, such as chitosan macromolecules, with complex solubility depending on the charge balance. The resulting P(NIPAM-SSNa) nanogels combine thermosensitivity with polyelectrolyte functionality, making them suitable for drug delivery, wastewater treatment, and emulsion stabilization. The work provides insights into designing multifunctional responsive nanocarriers with tunable properties.

A series of novel functional polycarbonates, specifically poly(solketal glycidyl ether carbonate-co-propylene carbonate)s with varying compositions, were synthesized through the ring-opening copolymerization of solketal glycidyl ether, propylene oxide, and carbon dioxide. The reaction was catalyzed by rac-(salcy)CoIIIX complexes with bis(triphenylphosphine)iminium salts as co-catalysts, achieving high selectivity. The resulting terpolymers exhibited number-average molecular weights ranging from 2 × 104 to 1 × 105 and a narrow, bimodal molecular weight distribution, with dispersities of 1.02–1.07 for each mode. Interestingly, the addition of a small amount of water to the reaction mixture yielded a terpolymer with a unimodal molecular weight distribution and a dispersity of 1.11. Subsequent acidic hydrolysis of the solketal protective groups produced poly(glyceryl glycerol carbonate-co-propylene carbonate). All terpolymers were amorphous, with Tg near or below room temperature. The hydroxyl-functional polycarbonates underwent cyclodepolymerization under milder conditions compared to polycarbonates with protected hydroxyl groups.

In this work we report the synthesis of new aminobisthiophenol ligands BnN{CH2[(6-R)(2-HS)C6H3]}2, R = (5a); R = Ph (5b), and also four-coordinated methyl aluminum complexes BnN{CH2[(6-R)(2-S-) C6H3]}2Al-Me, R = H (6a); R = Ph (6b). It was found that ligands of this type, according to 1H and 13C NMR data, as well as X-ray diffraction (for complex 6a), successfully stabilize aluminum complexes in the monomeric form. The composition of the obtained complexes is confirmed by elemental analysis data. X-ray diffraction study of aluminum complex 6a showed that it is four-coordinate species with a distorted trigonal monopyramidal coordination core. Complexes 6a and 6b (in the presence of benzyl alcohol) were studied as initiators of ring opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL), rac-lactide (rac-LA), and copolymerization of l-lactide (L LA) and epsilon-CL. Complex 6b showed greater activity in ROP of rac-LA ([rac-LA]:[6b]:[BnOH]=100:1:1; full conversion of rac-LA polymerization in toluene solution at 80 degrees C was achieved after 48 h) and epsilon-CL ([epsilon-CL]:[6b]: [BnOH]=100:1:1; full conversion of epsilon-CL polymerization in toluene solution at 80 degrees C was achieved after 30 min and at room temperature after 6 h) compared to 6a.

The search for new initiators based on nontoxic metal complexes, allowing for the controlled production of polycaprolactone (PCL) and polylactide (PLA) is an actual task. In the present work, we report the synthesis of aluminum complexes 6a and 6b based on substituted 2,6-bis(2-hydroxyphenyl)pyridine pro-ligands. The compositions and structures of the novel compounds were established by elemental analysis and 1H, 13C, NMR spectroscopy in the solid state by X-ray diffraction analysis (6a and 6b). All the synthesized aluminum complexes are monomeric. Complexes 6a and 6b (in presence of benzyl alcohol (BnOH)) turned out to be active in the ring opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL), L-, rac-lactide (L-, rac-LA) gave PCL and PLA with high molecular weights. The mechanism of the polymerization reaction for compounds & Scy;, 6a, and 6b was also investigated using the density functional theory (DFT) method. The substituent effect analyzed in terms of percent buried volume and non-covalent interactions. The values of calculated Gibbs free activation energies correspond to the trend found experimentally.

To prepare novel biodegradable copolymers with functional substituents that are distributed statistically or randomly over the macromolecule chain and have improved characteristics compared to homopolymers, we conducted a series of synthetic experiments with a novel cyclic monomer, 5-(benzyloxy)-1,3-dioxepan-2-one (4). This compound was synthesized, and its homopolymer, as well as its copolymers with L-lactide, ε-caprolactone and trimethylene carbonate, were prepared in a polymerization solution with stannous octoate as the initiator. The formation of the copolymers was confirmed using NMR spectroscopy and DSC data. The distribution of the monomeric units of the substituted 7CC in the copolymers with L-lactide and ε-caprolactone is random, as it is close to a statistical distribution. The copolymer with TMC is a gradient copolymer due to the different rates of monomer polymerization. The copolymer with a composition of 10(ε-CL):1(carbonate 4) can be considered a promising polymer after the deprotection of the hydroxy group for the inoculation of the functional substituents due to its convenience of preparation and properties similar to those of poly(ε-caprolactone).

Polymerization-induced self-assembly (PISA) is a powerful and versatile technique for producing colloidal dispersions of block copolymer particles with desired morphologies. Currently, PISA can be carried out in various media, over a wide range of temperatures, and using different mechanisms. This method enables the production of biodegradable objects and particles with various functionalities and stimuli sensitivity. Consequently, PISA offers a broad spectrum of potential commercial applications. The aim of this review is to provide an overview of the current state of rational synthesis of block copolymer particles with diverse morphologies using various PISA techniques and mechanisms. The discussion begins with an examination of the main thermodynamic, kinetic, and structural aspects of block copolymer micellization, followed by an exploration of the key principles of PISA in the formation of gradient and block copolymers. The review also delves into the main mechanisms of PISA implementation and the principles governing particle morphology. Finally, the potential future developments in PISA are considered.

The simple approach of increasing the elastic properties of atactic poly(propylene carbonate) (PPC) with Mn = 71.4 kDa, ĐM = Mw/Mn = 1.86, and predominantly carbonate units (>99%) is suggested by selecting the appropriate hot pressing temperature for PPC between 110 and 140 °C. Atactic PPC is synthesized through ring-opening copolymerization of (rac)-propylene oxide and CO2 mediated by racemic salen complex of Co(III). Hot pressing PPC results in the release of a small amount of propylene carbonate (PC), sufficient to lower the glass transition temperature from 39.4 to 26.1 °C. Consequently, increasing the pressing temperature from 110 to 140 °C generates materials with a reduced modulus of elasticity (from 1.94 to 0.09 GPa), yield strength (from 38 to 2 MPa) and increased tensile elongation (from 140 to 940%). Thermomechanical analysis has shown a significant expansion in sample volume by hundreds of percent within the 80–130 °C range. PPC also displays large, reversible deformations, which can be utilized by creating shape memory materials.

Designing a catalyst for random copolymerization by ring-opening polymerization (ROP) is an actual task. In the present work, we report the synthesis of aluminum complexes (R ' = Et, R '' = Ph (5); R ' = Bn, R '' = Ph (6); R ' = t-Bu, R '' = Ph (7); R ' = R '' = Ph (8)] based on diamidoamine pro-ligands. The reactivity of complexes in the ROP of epsilon-caprolactone (epsilon-CL) was studied. The highest activity was shown by complexes 5 and 8, containing phenyl groups at the terminal nitrogen atoms of the ligand in the ROP of epsilon-CL. Also, complex 5 was an effective initiator of copolymerization of 2-(benzyloxycarbonyl)-2-methyltrimethylene carbonate (TMCR) and L-lactide (L-LA) which led to the formation of a random copolymer.

In ring-opening polymerization (ROP) of cyclic esters, the rational design of the catalyst is generally applied to solve the task of providing polyester biocompatibility (non-toxicity) and the problem of copolymer homogeneity when using comonomers of different nature (e. g. lactones and lactides). In the present work, we report the synthesis of aluminum and titanium complexes, based on substituted 2,6-bis(2-hydroxyphenyl)pyridine pro-ligands 1 and 2. It was found that the structure of the pro-ligand drastically affect the structure of the reaction product. Pro-ligand 2 with a bulky tert‑butyl group leads to the monomeric complexes 6 (LAlMe) and 7 (LTi(OiPr)2), while the ligands with less bulky groups lead to the oligomeric Al-containing compounds 3 and 4, and in the case of Ti bis-ligand complex 5 is formed. Complexes 6 (in presence of BnOH) and 7 turned out to be active in the ROP of ε-caprolactone and l-lactide and gave PCL and PLA with high molecular masses. Compound 6 was an effective initiator of copolymerization of ε-caprolactone and l-lactide which led to statistical copolymer poly(LA-stat-CL) with comonomer subunits ratio of 1:1.

A comparative study of the copolymerization of racemic propylene oxide (PO) with CO2 catalyzed by racemic (salcy)CoX (salcy = N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-diaminocyclohexane; X = perfluorobenzoate (OBzF5) or 2,4-dinitrophenoxy (DNP)) in the presence of a [PPN]Cl ([PPN] = bis(triphenylphosphine)iminium) cocatalyst is performed in bulk at 21 °C and a 2.5 MPa pressure of CO2. The increase in the nucleophilicity of an attacking anion results in the increase in the copolymerization rate. Racemic (salcy)CoX provides a high selectivity of the copolymerization, which can be higher than 99%, and the living polymerization mechanism. Poly(propylene carbonate) (PPC) with bimodal molecular weight distribution (MWD) is formed throughout copolymerization. Both modes are living and are characterized by low dispersity, while their contribution to MWD depends on the nature of the attacking anion. The racemic (salcy)CoDNP/[PPN]DNP system is found to be preferable for the production of PPC with a high yield and selectivity.

The racemic salen complex of cobalt(iii) with pentafluorobenzoate axial ligand provides the synthesis of high molecular weight amorphous polypropylene carbonate and its full conversion into propylene carbonate.

RAFT polymerization was applied for the synthesis of hydrophilic poly(N,N-dimethylaminoethyl methacrylate) and random copolymers of N,N-dimethylaminoethyl methacrylate, containing 5 or 10 mol

Binary and ternary copolymers of acrylonitrile (AN), tert-butyl acrylate (TBA), and n-butyl acrylate (BA) are synthesized through conventional radical polymerization in DMSO in the presence of 2-mercaptoethanol. The thermal behavior of binary and ternary copolymers is studied under argon atmosphere and in air. It is demonstrated that the copolymers of AN contain 1–10 mol.% of TBA split isobutylene upon heating above 160 °C, resulting in the formation of the units of acrylic acid in the chain. The carboxylic groups formed in situ are responsible for the ionic mechanism of cyclization, which starts at lower temperatures compared with pure polyacrylonitrile (PAN) or AN copolymer with BA. The activation energy of cyclization through ionic and radical mechanisms depends on copolymer composition. For the ionic mechanism, the activation energy lies in the range ca. 100–130 kJ/mole, while for the radical mechanism, it lies in the range ca. 150–190 kJ/mole. The increase in the TBA molar part in the copolymer is followed by faster consumption of nitrile groups and the evolution of a ladder structure in both binary and ternary copolymers. Thus, the incorporation of a certain amount of TBA in PAN or its copolymer with BA allows tuning the temperature range of cyclization. This feature seems attractive for applications in the production of melt-spun PAN by choosing the appropriate copolymer composition and heating mode.

Carbon dioxide (CO2) plays a vital role in organic and polymer chemistry as a source of cheap and available raw material for the synthesis of many valuable products, including polymer materials with a specified set of properties, and as a solvent for chemical reactions. This review is devoted to the synthesis, properties and applications of polycarbonates obtained by copolymerization of CO2 with epoxides, a hot topic that has aroused great interest among the scientific community and industry representatives. The existing data on the catalytic systems used for the synthesis of polycarbonates are analyzed and summarized, depolymerization of polycarbonates, which is a key aspect in the polymer recycling, is discussed, information on the properties and applications of polycarbonates is systematized, and prospects for the development of this area of chemistry are considered. Bibliography — 438 references.

In this study, ultrafiltration membranes were developed via a nonsolvent-induced phase separation method for the removal of asphaltenes from crude oil. Polyacrylonitrile (PAN) and acrylonitrile copolymers with acrylic acid were used as membrane materials. Copolymerizing acrylonitrile with acrylic acid resulted in an improvement in the fouling resistance of the membranes. The addition of 10% of acrylic acid to the polymer chain decreases the water contact angle from 71° to 43°, reducing both the total fouling and irreversible fouling compared to membranes made from a PAN homopolymer. The obtained membranes with a pore size of 32–55 nm demonstrated a pure toluene permeance of 84.8–130.4 L/(m2·h·bar) and asphaltene rejection from oil/toluene solutions (100 g/L) of 33–95%. An analysis of the asphaltene rejection values revealed that the addition of acrylic acid increases the rejection values in comparison to PAN membranes with the same pore size. Our results suggest that the acrylonitrile–acrylic acid copolymer ultrafiltration membranes have promising potential for the efficient removal of asphaltenes from crude oil.

The influence of alkyl acrylate comonomers in the rank of methyl- (MA), butyl- (BA), ethylhexyl- (EGA), and lauryl- (LA) in ternary copolymers based on acrylonitrile, alkyl acrylate and acrylamide (PAN-alkyl acrylate) on their solutions rheological behavior in dimethyl sulfoxide (DMSO), and mechanical properties of the spun fibers have been investigated. To reveal the role of molecular weight, two series of copolymers with molecular weights of ~50 and 150 kg/mol have been studied. It was shown that the nature of the alkyl acrylate does not significantly affect the rheological behavior of their solutions regardless of the length of the alkyl substituent and the content of the alkyl acrylate in copolymers. An exception is the high-molecular PAN-LA, which is characterized by a non-Newtonian behavior at lower concentrations. Two series of fibers were spun from the characterized ranks of low and high-molecular-weight copolymer solutions. For all copolymers, a 2.5–5-fold increase in the strength and elastic modulus of the fiber was found with an increase in Mw. It has been shown that PAN-MA and PAN-LA fibers have a tensile strength of 800 MPa that is 1.5–3 times higher than that of other copolymers spun in the same conditions.