Search Results (1,346)

This study investigates the effects of hydration, temperature, and γ-irradiation on the structural, thermal, and mechanical properties of Lactoprene^® 7415, a linear block copolymer consisting of 74% lactide, 15% trimethylene carbonate, 11% ε-caprolactone repeating units, and 40 wt% β-TCP/Lactoprene^® 7415 composite. Techniques including static and dynamic mechanical testing or differential scanning calorimetry have evidenced structural changes resulting from irradiation- or water-induced crystallinity, crosslinking, chain scission or plasticization. Notably, hydration and physiological temperatures reduced the mechanical properties but conferred hyperelastic characteristics to the polymeric and composite samples. γ-irradiation was detrimental for the mechanical properties, except for those of the pure polymer in dry conditions. Our results evidence a complex interplay between the polymer, particles, temperature, hydration and water. Such observations could have implications in future designs and investigations of composite materials for scaffold-guided bone regeneration (SGBR), such as sterilization processes or minimally invasive surgery. Full article

The current paper aims to study the thermal stability of ethylene–propylene–diene monomer (EPDM) and styrene–ethylene–butylene–styrene (SEBS) block copolymer attained by radiation processing and evaluated by chemiluminescence (CL). Three blends with different weight ratios (1:3, 1:1 and 3:1), as well as individual rubbers, are γ-irradiated at 25, 50, 100 and 150 kGy. Their thermal stabilities are intercompared, and the activation energies required for oxidative degradation are calculated by using the values of oxidation induction times. Another investigation concerning the development of gel is in good agreement with the CL results. The aspects related to the mechanisms of the radiation fragmentation of blended components are discussed. The contributions of the blending components are evaluated based on the peculiar kinetic parameters, namely oxidation induction time (OIT) and onset oxidation temperatures (OOTs). It is clearly demonstrated that the EPDM component serves as the main source of radicals required for crosslinking, while the SEBS skeletons become the structural frames for the new crosslinked branches. The activation energies increase from 50 kJ mol⁻¹ to 59 kJ mol⁻¹ for unirradiated materials, but the increase for the blends exposed to 100 kGy is significantly larger from 41 kJ mol⁻¹ to 54 KJ mol⁻¹. The growth in the blending proportion of SEBS improves the thermal stability of the resulting materials. It is observed that the largest differences in the thermal resistances of γ-irradiated compounds are obtained for the samples exposed at 150 kGy, when the participation of each of the components is taken into account. This study highlights the research on and the productive methods of polymer processing, and the study of the irradiation of blends generates high-performance technical articles by the appropriate selection of technological parameters. Full article

Homopolymer addition is a widely used strategy to dilate the microdomain spacing of block copolymers, yet the attainable dilation is often limited by macrophase separation in conventional blends at elevated homopolymer loading. In this work, we investigate an architectural route to suppress macrophase separation while retaining homopolymer-driven dilation: a covalently hybridized bottlebrush copolymer (CH-BBC), a copolymacromer-like bottlebrush architecture in which symmetric AB diblock side chains and A-type homopolymer side chains are covalently grafted to a common backbone. Using dissipative particle dynamics (DPD) simulations, we directly compare the phase behavior of CH-BBC melts with that of composition-matched blends of symmetric AB diblocks and A-type homopolymers. Across the explored window, CH-BBC exhibits microphase morphologies and disorder without an observable two-phase region, whereas the corresponding blends show extensive two-phase coexistence at elevated homopolymer loading. Lamellar analysis and one-dimensional density decompositions further reveal that CH-BBC enables substantially larger microphase dilation and stronger selective swelling of the A-rich domain because tethered A-type homopolymer segments preferentially occupy and dilate the A-rich domain interior while diblock A segments remain localized near interfaces. Full article

To address the prominent problem of early rutting distress in asphalt pavements under heavy-load traffic in China, this study proposes a composite modifier consisting of direct coal liquefaction residue (DCLR), styrene–butadiene–styrene block copolymer (SBS), and styrene–butadiene rubber (SBR). The preparation process and formula were optimized through single-factor experiments and orthogonal tests. Systematic investigations were conducted on its conventional performance, water damage resistance, aging resistance, fatigue performance, rheological properties, and microscopic mechanism, with comparisons made against base asphalt, single DCLR-modified asphalt, SBS-modified asphalt, and SBS/SBR-modified asphalt. The results indicate that the optimal preparation process for the novel composite high-modulus modified asphalt is as follows: DCLR particle size of 0.3 mm, addition in molten state, shear temperature of 170 °C, shear rate of 5000 r·min⁻¹, shear time of 50 min. The optimal formula is 10% DCLR + 3% SBS + 2% SBR + 3% compatibilizer, with the addition sequence of “DCLR → SBS + compatibilizer → SBR”. This asphalt exhibits a softening point of 77.8 ± 2.1 °C, a Brookfield viscosity at 135 °C of 1.928 ± 0.105 Pa·s, and a grading of 5 for adhesion to aggregates; the rutting factor at 64 °C reaches 10.8 ± 0.9 kPa (6.43 times that of the base asphalt), the creep stiffness at −12 °C is 136 ± 12.5 MPa, and the low-temperature limit temperature is −17 °C; the freeze–thaw splitting strength ratio (TSR) is 94.6 ± 1.8%, and both aging resistance and water damage resistance are significantly superior to those of the control group asphalts (p < 0.05). The novel composite high-modulus modified asphalt showed improved overall laboratory performance and may be suitable for heavy-load traffic and complex climatic conditions, however, field validation is needed. Full article

The performance of recycled hot-mix asphalt mixtures (RHAM) is strongly governed by the extent and uniformity of interactions between the aged binder in reclaimed asphalt pavement (RAP) and the virgin binder. However, in current engineering practice, it remains difficult to accurately evaluate the blending degree of aged and virgin asphalt during RHAM production, where the blending degree refers to the extent and uniformity of binder interaction during hot mixing. Moreover, influenced by various construction-related factors, the uniformity of interfacial diffusion between the two asphalt layers is also hard to control, which compromises the durability of RHAM. To address these issues, fluorescence microscopy was used to quantitatively characterize the blending behavior of aged and virgin asphalt, and Fourier transform infrared spectroscopy (FTIR) was employed to investigate the interfacial diffusion process and its evolution under time-temperature coupling conditions from plant production to field paving. The results indicate that, owing to the fluorescent characteristics of the Styrene-butadiene-styrene block copolymer (SBS) modifier in polymer-modified asphalt, the blending behavior during hot mixing can be quantitatively characterized by the fluorescent area and its areal proportion, providing a rapid solution for quantitative evaluation during RHAM production. Increasing the preheating temperature of RAP, extending mixing time, raising mixing temperature, and adopting Mixing Sequence I reduced the proportion of fluorescent area, suggesting improved blending between aged and virgin asphalt. After blending, the interfacial diffusion between aged and virgin asphalt occurs within the RHAM; the uniformity of this diffusion becomes more pronounced as the elapsed duration from production to paving increases. Nevertheless, excessively long duration may induce secondary aging of the blended binder. Accordingly, the duration is recommended to be controlled at approximately 90 min and should not exceed 180 min. By elucidating the blending and diffusion behaviors of aged and virgin asphalt, this study provides practical guidance for contractors in controlling production-process parameters for RHAM. Full article

This review presents a comprehensive analysis of modern thermosensitive polymer systems for in situ systems (ISSs) which are used for targeted drug delivery in situ. The main classes of polymers used to create “smart” hydrogels that undergo a “sol–gel” phase transition in response to a temperature stimulus in the physiological range are considered. Key representatives of thermosensitive matrices are described in detail: synthetic block copolymers (poloxamers, block copolymers of polylactic-co-polyglycolic acid with polyethyleneglycol, etc.) and natural, modified natural, and semi-synthetic polymers (chitosan, including in combination with β-glycerophosphate, xyloglucan, etc.). This paper systematizes the advantages and disadvantages of various thermosensitive systems and highlights the key risks in their pharmaceutical development, including the influence of the nature and concentration of the active pharmaceutical ingredients and excipients on the rheological properties and phase transition temperature. Particular attention is paid to the difference between thermoreversible and irreversible gel-forming systems. Modern in vitro, ex vivo, and in vivo methods for evaluating critical quality parameters of thermosensitive systems, such as gelation temperature and time, gel strength, mucoadhesive properties, and release kinetics, are discussed. The need to develop standardized and biologically relevant methods to improve the reproducibility and success of preclinical studies is emphasized. The review is intended to help researchers to make informed choices about polymer matrices and optimize compositions for successful pharmaceutical development. Full article

Enhancing the solubility and processability of graphene remains a critical challenge, limiting its integration into advanced materials systems. In this work, poly(tert-butyl acrylate) (PtBA) and poly(N-isopropyl acrylamide) (PNIPAM) were grafted onto graphene via controlled atom transfer radical polymerization (ATRP) to create well-defined polymer–graphene hybrids with tunable interfacial properties. ATRP enabled the synthesis of PtBA and PNIPAM homopolymers with narrow molecular weight distributions and systematically varied chain lengths (4–18 kDa), allowing direct correlation between polymer architecture and material performance. Notably, the thermos-responsive behavior of PNIPAM was strongly dependent on chain length, highlighting the importance of controlled polymer design. Raman and FTIR spectroscopy confirmed successful grafting and chemical modification of the graphene surface. In addition, pilot studies demonstrate the ATRP synthesis of PtBA-b-PNIPAM block copolymers and their hydrolysis to PAA-b-PNIPAM, providing a platform for future development of multifunctional graphene interfaces. Overall, this study establishes a versatile and precisely controlled route for engineering polymer-grafted graphene with enhanced solubility and tunable functionality, enabling broader applications in smart materials and hybrid nanocomposites. Full article

Graphoepitaxy provides a robust route to align lamellar block copolymers in topographic trenches, yet alignment often degrades rapidly as the trench width increases into the wide-trench regime. Here, mesoscale density functional simulations under thermal annealing are used to quantify width- and geometry-dependent ordering of symmetric lamella-forming block copolymers confined in trenches. A Fourier-based alignment metric reveals a sharp, sigmoidal decay of alignment with trench width normalized by the natural lamellar period, indicating a crossover between (i) a globally aligned state established by wall-guided propagation and (ii) a misoriented, kinetically trapped state produced by bulk-like interior nucleation followed by domain impingement. This width dependence is well captured by a logistic form, yielding a characteristic crossover width and transition sharpness that compactly describe the accessible alignment window. Parameter sweeps show that increasing incompatibility shifts the crossover to smaller widths, whereas stronger sidewall surface fields extend the accessible width range with diminishing returns at large fields; in the range examined, film thickness has little influence on the crossover. Finally, simulations in trapezoidal trenches demonstrate that high alignment persists for moderate sidewall taper, while larger taper promotes lamellar bending and defects. A geometric criterion based on the variation in trench width across the film thickness, using a numerical threshold derived from strong-segregation theory, rationalizes the observed onset of degradation when this variation approaches approximately 1.4 lamellar periods. These results provide a mechanistic framework and quantitative guidelines for extending graphoepitaxial lamellar alignment beyond the narrow-confinement regime. Full article

This study reports the synthesis and catalytic evaluation of a series of imidazolium-based polymeric ionic liquids (PILs) for the cycloaddition of CO₂ to epichlorohydrin (ECH). The synthesized catalysts include homopolymers, poly(3-hydroxyethyl-1-vinylimidazole chloride) (p[HVIm][Cl]) and poly(3-carboxymethyl-1-vinylimidazole chloride) (p[CMVIm][Cl]), and their block copolymers with polystyrene, synthesized for the first time, pS-b-p[HVIm][Cl] and pS-b-p[CMVIm][Cl]. Structural characterization by NMR, IR spectroscopy, and gel permeation chromatography confirmed the successful synthesis. The block copolymers exhibited a low polydispersity index (PDI 1.1–1.2), which is indicative of homogeneous chain lengths and the propensity to form ordered nanostructures, whereas the homopolymers showed higher PDI (2.4–2.9). Catalytic testing at 90 °C and 1 MPa CO₂ for 4 h revealed a clear activity trend: p[CMVIm][Cl] < p[HVIm][Cl] < pS-b-p[CMVIm][Cl] < pS-b-p[HVIm][Cl], with conversions exceeding 75% for all catalysts and a maximum of 82.69% for pS-b-p[HVIm][Cl]. These results demonstrate that the catalytic performance of PILs is governed by a synergistic interplay between the local chemical functionality of the ionic moiety and the overall polymer architecture. Based on these results, the synthesized polymeric ionic liquids, particularly pS-b-p[HVIm][Cl], demonstrate strong potential for creating multifunctional materials. Their ability to self-assemble into ordered nanostructures with distinct hydrophobic and hydrophilic domains provides a foundational architecture for combined gas separation and catalysis. The observed “micellar catalytic effect”, which enhances local reagent concentration near active sites, could be leveraged in a membrane reactor to simultaneously capture and convert CO₂ directly within the membrane. This integrated “separation–reaction” approach represents a promising strategy for advancing circular carbon economy technologies. Full article

Polytetrafluoroethylene (PTFE) is attractive for high-frequency communications but adheres very poorly to other materials due to its very low surface energy. Conventionally, surface treatments of PTFE are used to increase the polarity of the PTFE surface and enable bonding to materials with increased surface free energy. However, surface treatments are difficult to scale, can damage surfaces, and often lack reproducibility. Therefore, developing a material that can make PTFE adhere well to other materials without surface treatment is highly desirable. In this study, we aimed to develop a new material with strong adhesion to PTFE. We synthesized three polymer gels from dodecyl acrylate (DA) and 2-(dimethylamino) ethyl acrylate (DMAE): the homopolymer gels PDEAE and PDA, and the copolymer gel P(DEAE-co-DA). The copolymer gel P(DEAE-co-DA) exhibited high pressure-sensitive adhesion to PTFE, recording the highest adhesive strength (F = 430.0 N/m) and the highest peel energy (G = 713.4 J/m²) compared to the homopolymer gels PDEAE and PDA. Mechanical testing showed PDEAE had the greatest strength and toughness, PDA balanced stiffness and extensibility, and P(DEAE-co-DA) was the most flexible and extensible. The P(DEAE-co-DA) with the smoothest surface (Sz ≈ 0.176 µm) showed the highest F and G, implying that surface roughness did not contribute significantly to the interfacial adhesion between the gels and the PTFE. Based on the surface free energy ${\sigma }_s$ and work of adhesion $W_a$ values, the adhesive strength to PTFE was predicted to be PDEAE > P(DEAE-co-DA) > PDA, but the measured G in peel tests contradicted this, indicating that the gels’ viscoelastic deformation and energy dissipation dominate the measured F and G. The frequency-dependent viscoelastic data and relaxation times τ and activation energies $E_a$ suggested optimal adhesion requires a balance of adhesion (mobility for energy dissipation (short τ, low $E_a$)) and sufficient cohesion (high G′). P(DEAE-co-DA) achieved this balance, explaining its high measured F and G. With precise control of polymer chain mobility, the adhesion of P(DEAE-co-DA) gels can likely be improved further. Future work will employ block copolymerization and monomer-ratio control to tune molecular motion and enhance adhesion to PTFE. Full article

Amphiphilic copolymers based on polystyrene and polyglycidol combine the chemical inertness of polystyrene with the biocompatibility of polyglycidol, making them attractive materials for polymeric micelles. While comb-like architectures have been explored to control micellization behavior and biological response, a direct comparison between comb-like and coil-comb topologies in polystyrene–polyglycidol copolymers at identical polyglycidol content remains insufficiently investigated. In this work, amphiphilic comb-like and coil-comb polystyrene–polyglycidol copolymers were synthesized via copper-catalyzed azide–alkyne click chemistry by grafting a monoalkyne-terminated polyglycidol precursor onto azide-functionalized random and block styrene copolymers. The copolymers were characterized by size exclusion chromatography and nuclear magnetic resonance. Polymeric micelles were prepared by nanoprecipitation, and their self-assembly in aqueous solution was investigated by critical micelle concentration determination, dynamic and electrophoretic light scattering, and atomic force microscopy. Both copolymers formed stable aqueous dispersions and exhibited comparable critical micelle concentrations. At identical polyglycidol content, the random copolymer formed a uniform, monomodal micellar population, whereas the block-based coil-comb architecture led to bimodal size distributions, indicating the coexistence of two distinct micellar populations. The investigated systems showed low cytotoxicity and did not induce significant oxidative stress within the studied concentration range. On isolated rat brain sub-cellular fractions (synaptosomes, mitochondria and microsomes), administered alone, the comb-like and coil-comb polystyrene-polyglycidol copolymers did not reveal statistically significant neurotoxic effects. The results demonstrate that macromolecular architecture plays a key role in governing micellar organization and in vitro biological response in polystyrene–polyglycidol copolymers, highlighting their potential as architecture-controlled polymer-based nanocarriers. Full article

This study investigates how natural fillers of different origins and morphologies influence the structural, thermal, rheological, and mechanical properties of thermoplastic elastomers (TPEs). Two series of materials were prepared: one based on a biobased matrix, poly(butylene 2,5-furandicarboxylate)-block-poly(tetramethylene oxide) (PBF-PTMO), and one based on a petroleum-derived matrix, poly(butylene terephthalate)-block-poly(tetramethylene oxide) (PBT-PTMO). Both series incorporated a range of natural modifiers, i.e., lignocellulosic fibers and ground fractions of Arundo donax L., cyanobacterial biomass (Spirulina platensis), and silica-rich mineral dust originating from volcanic stone quarries. The materials were obtained via melt blending, while the reference matrices (neat block copolymers) were synthesized through melt polycondensation. The chemical structure and limiting viscosity number (LVN) of the neat matrices were confirmed, while differential scanning calorimetry (DSC) provided insight into their morphology and phase composition. Scanning electron microscopy (SEM) was employed to evaluate the morphology and distribution of the modifiers within the polymer matrices. To assess how the fillers influenced processing windows and performance, thermogravimetric analysis (TGA), oscillatory rheological measurements, and tensile testing were performed. The results provide insight into structure–property relationships governing natural filler–TPE interactions and support the development of more sustainable elastomeric composites with tailored performance. Full article

Background: Pentamidine isethionate (PTM) and miltefosine (MF) are clinically relevant antiparasitic agents whose use is limited by toxicity, emerging resistance, and the lack of effective co-delivery strategies. Tetronic^® 1307 (T1307), an amphiphilic and thermoresponsive block copolymer, was investigated as a carrier to enable their combination therapy. Methods: PTM and MF were formulated in T1307-based micelles and thermoresponsive gels. The systems were characterized by small-angle neutron scattering (SANS), dynamic light scattering (DLS), and nuclear magnetic resonance spectroscopy (NMR). Antiparasitic activity was evaluated against Leishmania major promastigotes. Results: MF formed stable micelles that efficiently incorporated PTM, generating a “drug-in-drug” architecture. While T1307 alone showed limited PTM loading, MF promoted mixed micelle formation and enhanced PTM incorporation. At physiological temperature and adequate copolymer concentrations, drug-loaded micelles formed thermoreversible gels suitable for topical application. The combined formulations preserved drug activity and exhibited synergistic effects against L. major. Conclusions: T1307 is a promising platform for the co-delivery of PTM and MF, enabling synergistic combination therapy and thermoresponsive gel formation with potential to reduce systemic toxicity and improve treatment administration. Full article

The development of biodegradable ABA-type triblock copolymers with tailored thermo-mechanical performance requires precise control over polymer architecture and phase behavior. In this study, PLLA-based ABA triblock copolymers were synthesized using two structurally distinct, fully bio-based soft segments: poly(methyl ricinoleate) (PMR) and poly(1,3-propanediol) (PPD). To the best of our knowledge, this is the first report on PLLA triblock copolymers incorporating PMR as a renewable soft middle block. Hydroxyl-terminated PMR and PPD were employed as macroinitiators for the controlled ring-opening polymerization of L-lactide, enabling systematic variation in block composition and molecular weight. Structural characterization confirmed successful block formation, while thermal and mechanical analyses revealed pronounced differences in phase separation and structure–property relationships. Copolymers containing PMR exhibited enhanced phase separation, increased crystallinity of PLLA domains, and significantly improved elongation at break, attributed to the presence of pendant chains in the soft segment. In contrast, PPD-based copolymers showed reduced phase separation and more PLA-like mechanical behavior. These results demonstrate that the chemical architecture of bio-based soft segments plays a decisive role in governing the thermo-mechanical performance of PLLA-based triblock copolymers. Full article