A systematic study on the chemical functionalization of inorganic surfaces with multifunctional initiators (MIs) for radical polymerization was conducted. The modification involved sequential surface amination with 3-aminopropyltriethoxysilane (APTES), covalent attachment of MIs bearing reactive anhydride groups, and subsequent graft polymerization. Optimized amination conditions produced a uniform monomolecular coating (similar to 0.9 nm) with evenly distributed amino groups suitable for anchoring the initiator. MI grafting resulted in stable nanocoatings with well-controlled thickness and grafting density. The correlation of ellipsometry and contact angle measurements revealed a two-stage kinetic behavior: an initial rapid attachment followed by a slower, self-limiting stage caused by steric hindrance. The structure of the initiator had a pronounced effect on surface coverage and wettability, with bulky cholesteryl substituents promoting higher hydrophobicity. AFM analysis confirmed the formation of continuous nanometer-thick coatings with uniform topography and roughness larger than that of APTES-modified substrates. Molecular modeling and experimental results demonstrated that compact MIs achieved the highest grafting density (similar to 3.6 molecules/nm & sup2;), while flexible or bulky architectures reduced packing efficiency. These findings establish clear structure - property correlations between MI architecture, grafting kinetics, and coating morphology. The developed approach enables the fabrication of ultrathin, stimuli-responsive polymer brush coatings with tunable physicochemical and biofunctional properties for applications in protein adsorption, tissue engineering, antibacterial surfaces, and functional nanocomposites.

Renewable polymer coatings grafted onto glass via SI-ARGET ATRP from castor seed oil-based monomers (CSM) exhibited unexpected dual temperature- and pH-dependent responses in wettability and morphology in the range of 5-45 degrees C. Homogeneous coatings (after 3 h, < 25 nm) were characterized with XPS, ToF-SIMS, AFM, ellipsometry, water contact angle CA, and the three-liquid method. The 'as-prepared' coatings (15 h of graft) revealed a temperature-dependent minimum in CA and a coincident maximum in surface roughness at 15-20 degrees C, with a U-shaped and an inverted U-shaped dependence, respectively. Temperature-induced transitions between rubbery, rubbery-flow, and viscous-flow states are postulated, with grafted chain rearrangements also reflected in the increase of the polar component of surface energy. After immersion in pH buffers, the U-shaped thermal response in the wettability of the coatings (15 h graft) is enhanced, with increased hydrophilicity, for pH 5 and 7 but destroyed for pH 3 and 9. The opposite temperature variation of surface roughness, determined for pH 7, is accompanied by pH-dependent morphological changes, observed at 20 degrees C. The pH-responsive behavior is related to the hydroxyl groups present in CSM. The polyCSM grafting coating is an excellent biobased candidate for the fabrication of biomaterials that additionally possess temperature- and pH-responsive properties.

Temperature-induced transitions in polymer systems, often governed by a phenomenon called critical solution temperatures (CSTs), lie on the basis of various advanced technologies such as tissues detachment, smart windows, enhanced DNA biosensors, etc. Despite this application-oriented progress, the molecular mechanisms of the temperature-induced transition based on CSTs remain often underexplored or weakly explained. In this review, we focus on the different molecular mechanisms driving CST-based transitions, systematizing information on homofunctional polymer systems. Understanding these mechanisms is crucial for manipulating temperature-sensitive properties, which offers significant potential for future innovations in smart materials.

To provide antifouling bioactive surfaces for biosensing and cell culture, we synthesized and characterized copolymer brush interfaces with minimized nonspecific adsorption combined with adjustable high-capacity bioconjugation of functional protein and examined the interfacial protein state that determines its biological activity. Brushes were fabricated using surface-initiated atom transfer radical polymerization with silicon-grafted chains copolymerized from 2-(2-methoxyethoxy)ethyl methacrylate (OEGMA) and methacrylic acid (MAA) taken in different proportions. For all P(OEGMA1-x-co-MAAx) coatings (0 ≤ x ≤ 1), X-ray photoelectron spectroscopy revealed the molar fraction x of MAA in the brush equal to that of the reaction mixture. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed a copolymer composition that is uniform with depth in the brush coatings, confirming a successful random copolymerization. Bioconjugation of immunoglobulin G antibody (IgG) within the brushes, enabled by the activation of MAA segments with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide (EDC/NHS), was examined together with nonspecific IgG adsorption to the nonactivated brushes using ToF-SIMS and fluorescence microscopy. Protein loading was controlled by copolymer composition and protein solution concentration. The optimal composition x = 0.25 was selected for the brushes with maximum bioconjugation (∼0.4 g/cm3) and low nonspecific adsorption. Protein loads per brush volume were estimated from ToF-SIMS depth profiles that evidenced IgG immobilization within the brush. For all P(OEGMA1-x-co-MAAx) brushes with conjugated IgG antibody, the coatings with x = 0.25 provided the highest amount of bound antigen with an antigen binding ratio higher than that of the PMAA coatings. This observation was related to the different interfacial antibody states in both coatings (determined by the residue involvement in the coupling with the MAA segments and the dominant antibody orientation), which were investigated with multivariate principal component analysis of ToF-SIMS data. Finally, human fibroblast cell culture showed the biocompatibility of the developed copolymer brush coatings, further promoted by brush conjugation with fibronectin.

PLA/PBAT-based (Ecovio) nanocomposites were prepared using both pristine and functionalized clays, including PBMA- and PBA-grafted brushes, which were selected for their surface energy compatibility with the PLA phase. XRD analysis confirmed the successful intercalation of clay and good dispersion within the polymer matrix. Thermal analysis revealed the typical two-step degradation pattern (PLA followed by PBAT), with APTESfunctionalized clays lowering the peak degradation temperature of PLA to 305 degrees C. In comparison, PBA-grafted clays increased it to 329 degrees C compared to 322 degrees C for neat Ecovio. The addition of nanoclays to Ecovio-based composites did not significantly affect the overall crystallinity of the system. Thermomechanical and FTIR analyses indicated that APTES promoted polymer degradation during processing, whereas PBA grafting helped mitigate these effects. Rheological measurements revealed increased melt elasticity in Ecovio nanocomposites containing PBA-grafted clays without compromising processability, a key advantage for compostable film applications in packaging. Overall, the inclusion of PBA-grafted clays improved both the compatibility and thermal stability of PLA/PBAT-based nanocomposites. Moreover, this work introduces, for the first time, a straightforward strategy for tuning the properties of multi-tonnage industrial composites such as Ecovio, providing a practical approach to enhance performance while preserving compostability.

This study examines the rheological properties and technological characteristics of five types of AzureFilm filament made from polylactic acid (PLA), modified with three kinds of wood fillers (bamboo, pine, and cork), as well as poly(p-phenylene pyromellitimide) (PPPI). The filaments underwent multiple processing steps, including grinding, drying, and melting, followed by injection molding. The rheological properties of the composites were measured in the molten state using a rotational rheometer at 210 degrees c. Notably, Cole-Cole and Van Gurp-Palmen (VGP) plots were created to analyze relaxation behavior, polydispersity, and interfacial interaction. Furthermore, thermal transitions and degradation were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), providing insights into the comparative effects of natural lignocellulosic fillers and a high-performance aromatic additive.

Poly(methacrylic acid) (PMAA) is a well-known pH-responsive polymer with under-explored temperature-responsive properties. This study investigated the temperature-responsive properties of PMAA-grafted brush coatings, synthesized via the SI-ATRP polymerization of sodium methacrylate (NaMAA) and methacrylic acid (MAA) on glass surfaces. Distinct water contact angles were observed for PMAA brush coatings fabricated from NaMAA (38 deg) and MAA (60 deg) solutions. The reduced wettability of PMAA brushes from MAA indicates a reduced exposure of the hydrophilic moieties acquired during synthesis, which is postulated to occur with a lower grafting density. PMAA brush coatings showed a lower critical solution temperature (LCST), characterized by changes in wettability and thickness; however, this transition was not observed after immersion in various pH buffer solutions. Although inhibited growth of cells cultured on PMAA brushes was previously reported, we observed that the increased hydrophobicity of PMAA coatings from MAA resulted in excellent biocompatibility, demonstrated by growth and viability of dermal fibroblast cultures, making them prospective for biomedical applications. However, the LCST transition of these coatings did not induce temperature-controlled changes in protein (BSA) adsorption and cell (fibroblast) morphology.

In an effort to provide a universal platform for remotely controlling the behavior of various cell lines, we present a strategy for fabricating 'smart' polymer sandwiches using a nanogel attached to temperature-responsive grafted brush coatings. These coatings can be easily modified to meet the requirements of specific cell types while preserving responsiveness. First, temperature-responsive grafted copolymer brush coatings of poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) with a small amount of hydroxyethyl methacrylate (HEMA) were synthesized on glass surfaces. Subsequent modifications involved using multifunctional alcohols, amines, or their combinations with proteins to react with divinyl sulfone, forming a cross-linked polymer matrix with a surface nanogel structure attached to grafted copolymer brushes containing hydroxyl groups. The resulting sandwich coatings were comprehensively characterized, revealing maintained temperature-responsiveness for various structures of the grafted nanogel. Compared with P(OEGMA-co-HEMA) brushes, these temperature-responsive sandwich coatings exhibited improved biocompatibility while retaining the ability to regulate cell morphology and detachment of dermal fibroblasts through external temperature control. Rheological analysis of live cells was performed on the developed platforms to reveal their impact on cellular behavior. The application of these new materials opens exciting possibilities for tissue engineering.

This review focuses on amphiphilic diesters and "gemini" surfactants synthesized from pyromellitic acid, polyethylene glycols, aliphatic alcohols, and cholesterol. The discussion encompasses their unique colloidal and chemical properties, with an emphasis on the relationship between critical micelle concentration and hydrophilic-lipophilic balance. Structural factors, particularly the length of the lipophilic substituents, significantly influence CMC values in aqueous systems. Additionally, the presence of carboxyl groups in the pyromellitic acid core allows for pH-dependent modulation of surface activity. The amphiphiles exhibit exceptional potential in forming micellar structures capable of solubilizing hydrophobic substances, including dyes, oils, cholesterol, and the bioactive compound curcumin. Beyond enhancing the stability of these substances, they enable controlled release mechanisms that mimic cellular membrane interactions. Such versatility positions the materials from amphiphilic diesters of pyromellitic acid as promising candidates for innovative applications in targeted drug delivery systems and as nanoreactors for synthesizing silver nanoparticles. This review underscores their potential in advancing nanotechnology and biomedical engineering.

Integrating antibacterial functionality directly into platforms for cell sheet engineering (CSE) would offer proactive defense against bacterial contamination and improve the safety and efficacy of CSE in cell-based therapies. This study demonstrates the potential of poly(4-vinylpyridine) polymer brushes with embedded copper nanoparticles (P4VP&Cu) as innovative CSE platforms, using the adult retinal pigment epithelial cell line (ARPE-19). The unique properties of such coatings, which combine the thermo-responsiveness of the polymer brush with the strong antibiocidal activity of copper, were traced using an interdisciplinary approach to provide information on the physicochemical properties of coatings, and confirm their cytocompatibility, and antibacterial effect through the contact- and release-killing mechanisms as a function of temperature. In particular, differentiated ARPE-19 cells cultured on P4VP coatings demonstrated spontaneous thermo-triggered detachment of intact cell sheets, which preserved their biological activity. This effect was maintained on P4VP&Cu coatings, which exhibited superior antibacterial activity without compromising cell viability in addition to resistance to protein adsorption. These findings highlight the potential of P4VP&Cu coatings as next-generation CSE platforms, combining effective antimicrobial defense with precise thermo-responsive functionality.

Plant oil-based acrylic monomers from hydrogenated sunflower (HFM), palm (PMM) and castor (CSM) oils were polymerized to investigate the effect of chemical composition on polymer phase transitions at temperatures relevant to physiological range. While HFM and PMM possess a highly differing content of saturated palmitic and stearic acids combined with unsaturated fatty acids, CSM contains primarily fragments based on monounsaturated ricinoleic hydroxy acid (up to 90%). Differential scanning calorimetry (DSC) measurements indicate that polymers from PMM and HFM are both semicrystalline (with Tm = -6 and -13 degrees C, respectively), while poly(CSM) appears to be amorphous (Tg = -49 degrees C). Considering the similarity in polymers' molar mass (Mn = 16 000-20 000 g mol-1), the observed thermal transitions can be explained by the formation of ordered morphological domains due to the presence of saturated palmitic and stearic acid fractions in poly(PMM) and poly(HFM). For copolymers of CSM, PMM and HFM (80 wt% of monomer feed) with styrene, DSC data show two transitions corresponding to the mobility of long alkyl fatty acid side fragments and the macromolecular backbone. For copolymers of PMM and HFM, comparable values (-52.8 and -55.5 degrees C, respectively) were obtained, while the second transition for poly(CSM-co-styrene) appears at 35 degrees C. We attribute this higher value to the presence of hydroxyl groups in ricinoleic acid fragments of CSM serving as additional chain transfer sites and the formation of macromolecular fractions enriched with polystyrene fragments. We expect that the temperature transitions obtained can be relevant to the future use of these polymers for biomedical applications, including the synthesis of polymer brushes. (c) 2024 Society of Chemical Industry.

Polymer nanocomposites, such as polyethylene terephthalate (PET)-clay systems, leverage intricate interactions between components to fine-tune their thermal, mechanical, and rheological properties. In our study, we functionalized montmorillonite clay nanofillers (CloisiteNa+) to fabricate recycled PET-clay nanocomposites. The nanofillers underwent a three-step functionalization process, involving the treatment with (3-Aminopropyl)triethoxysilane (APTES), the grafting of initiating coatings (multifunctional peroxide initiator, [MPI]) onto clay/APTES, and the subsequent fabrication of grafted brushes using poly(butyl methacrylate) (PBMA) or poly(butyl acrylate) (PBA). The functionalization process and the properties of the modified clay were successfully confirmed through Fourier-transform infrared spectroscopy and thermogravimetric analysis. The fabrication of nanocomposites, incorporating both clay and functionalized clay, influenced the thermal behavior of the composites, whereas the nanofillers had no discernible impact on the flow temperature. The PET and nanocomposites exhibited liquid viscoelastic behavior, with the exception of PET with clay, which displayed shear-thinning and "rubber-like" behavior. Rheological curves and x-ray diffraction (XRD) analysis indicated improved dispersion and compatibility for clay/APTES and clay functionalized with PBA-grafted brushes within the PET matrix. In some instances, the utilization of functionalized clay resulted in enhanced compatibility and customized properties in PET-organoclay nanocomposites compared with conventional fillers. These findings bear implications for a broad spectrum of applications involving PET-organoclay nanocomposites. PET nanocomposites based on the recycled PET with functionalized clay have improved properties. image

Responsive polymer systems have the ability to change properties or behavior in response to external stimuli. The properties of responsive polymer systems can be fine-tuned by adjusting the stimuli, enabling tailored responses for specific applications. These systems have applications in drug delivery, biosensors, tissue engineering, and more, as their ability to adapt and respond to dynamic environments leads to improved performance. However, challenges such as synthesis complexity, sensitivity limitations, and manufacturing issues need to be addressed for successful implementation. In our review, we provide a comprehensive summary on stimuli-responsive polymer systems, delving into the intricacies of their mechanisms and actions. Future developments should focus on precision medicine, multifunctionality, reversibility, bioinspired designs, and integration with advanced technologies, driving the dynamic growth of sensitive polymer systems in biomedical applications.

The fabrication of multifunctional, thermoresponsive platforms for regenerative medicine based on polymers that can be easily functionalized is one of the most important challenges in modern biomaterials science. In this study, we utilized atom transfer radical polymerization (ATRP) to produce two series of novel smart copolymer brush coatings. These coatings were based on copolymerizing 2-hydroxyethyl methacrylate (HEMA) with either oligo(ethylene glycol) methyl ether methacrylate (OEGMA) or N-isopropylacrylamide (NIPAM). The chemical compositions of the resulting brush coatings, namely, poly(oligo(ethylene glycol) methyl ether methacrylate-co-2-hydroxyethyl methacrylate) (P(OEGMA-co-HEMA)) and poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (P(NIPAM-co-HEMA)), were predicted using reactive ratios of the monomers. These predictions were then verified using time-of-flight-secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The thermoresponsiveness of the coatings was examined through water contact angle (CA) measurements at different temperatures, revealing a transition driven by lower critical solution temperature (LCST) or upper critical solution temperature (UCST) or a vanishing transition. The type of transition observed depended on the chemical composition of the coatings. Furthermore, it was demonstrated that the transition temperature of the coatings could be easily adjusted by modifying their composition. The topography of the coatings was characterized using atomic force microscopy (AFM). To assess the biocompatibility of the coatings, dermal fibroblast cultures were employed, and the results indicated that none of the coatings exhibited cytotoxicity. However, the shape and arrangement of the cells were significantly influenced by the chemical structure of the coating. Additionally, the viability of the cells was correlated with the wettability and roughness of the coatings, which determined the initial adhesion of the cells. Lastly, the temperature-induced changes in the properties of the fabricated copolymer coatings effectively controlled cell morphology, adhesion, and spontaneous detachment in a noninvasive, enzyme-free manner that was confirmed using optical microscopy.

Novel brush coatings were fabricated with glass surface-grafted chains copolymerized using surface-initiated atom transfer radical polymerization (SI-ATRP) from 2-(2-methoxyethoxy)ethyl methacrylate (OEGMA188) and acrylamide (AAm), taken in different proportions. P(OEGMA188-co-AAm) brushes with AAm mole fraction >44% (determined with XPS and TOF-SIMS spectroscopy) and nearly constant with the depth copolymer composition (TOF-SIMS profiling) exhibit unusual temperature -induced transformations: The contact angle of water droplets on P(OEGMA188-co-AAm) coatings increases by similar to 45 degrees with temperature, compared to 17-18 degrees for POEGMA188 and PAAm. The thickness of coatings immersed in water and the morphology of coatings imaged in air show a temperature response for POEGMA188 (using reflectance spectroscopy and AFM, respectively), but this response is weak for P(OEGMA188-co-AAm) and absent for PAAm. This suggests mechanisms more complex than a simple transition between hydrated loose coils and hydrophobic collapsed chains. For POEGMA188, the hydrogen bonds between the ether oxygens of poly(ethylene glycol) and water hydrogens are formed below the transition temperature Tc and disrupted above Tc when polymer-polymer interactions are favored. Different hydrogen bond structures of PAAm include free amide groups, cis-trans- multimers, and trans-multimers of amide groups. Here, hydrogen bonds between free amide groups and water dominate at T < Tc but structures favored at T > Tc, such as cis-trans-multimers and trans-multimers of amide groups, can still be hydrated. The enhanced temperature-dependent response of wettability for P(OEGMA188-co-AAm) with a high mole fraction of AAm suggests the formation at Tc of more hydrophobic structures, realized by hydrogen bonding between the ether oxygens of OEGMA188 and the amide fragments of AAm, where water molecules are caged. Furthermore, P(OEGMA188-co-AAm) coatings immersed in pH buffer solutions exhibit a 'schizophrenic' behavior in wettability, with transitions that mimic LCST and UCST for pH = 3, LCST for pH = 5 and 7, and any transition blocked for pH = 9.

The effect of temperature and buffer solutions with different pH (often used in biomedical applications) on the behavior of POEGMA brush coatings, synthesized without incorporated functional groups, was for the first time studied in details using water contact angle (CA) measurements and atomic force microscopy (AFM). Thermal response of grafted brush-coatings based on poly(oligo(ethylene glycol) methacrylate)s (POEGMA)s is driven by lower critical solution temperature (LCST) phenomenon. Obtained CA and AFM results suggest strong impact of the buffer solutions on the values of LCST transition and contact angle ranges, as well as on coatings morphology. In turn, ellipsometry data reflect penetration of salt ions from buffer solutions into brush-coatings. In contrast to “typical” behavior of POEGMA coatings in water, different mechanisms available below LCST in the buffer solutions destroy hydrated layers surrounding POEGMA macromolecules leading to their collapse.

New temperature-responsive hybrid nanomaterials based on modified halloysite nanotubes (HNTs) containing grafted polymer brushes with silver nanoparticles have been successfully fabricated. We used a three steps process including synthesis of the initiating coatings onto HNTs surface, fabrication of the POEGMA - poly(oligo (ethylene glycol)ethyl ether methacrylate) grafted brushes and synthesis of the silver nanoparticles (AgNPs). The synthesis and properties of hybrid nanomaterials were studied by FT-IR, TGA and DLS methods. It is shown that the introduction of AgNPs, formed from 0.005 M AgNO3 solution leads to a significant reduction of low critical solution temperature (LCST) of the polymer layer from 29.7 to 21.6?degrees C. The samples fabricated from 0.05 M AgNO3 solution did not evidence a temperature-induced transition, despite of the contents of AgNPs obtained for both solutions are almost identical (& AP; 4%w). The presence of AgNPs with sizes of ca. 20 nm was confirmed in the hybrids prepared from both AgNO3 concentrations by UV-vis spectroscopy, and electron microscopy. These temperature-responsive hybrid nanomaterials may be used for conservation of solid substrates, production of advanced medical facemasks, photothermal therapy against microorganisms and tumors etc.

The mechanism of protein adsorption on various surfaces of tailored functionality is often accessed by isothermal titration calorimetry (ITC), the powerful tool yielding the full set of thermodynamic parameters in one label-free experiment. In this work, the non-ionic polymer brushes with thermo-switchable hydrophilic-hydrophobic balance, based on diethylene glycol methacrylate (DEGMA) and 4-vinyl pyridine (4VP) copolymers, grafted to SiO2 nanoparticles, were titrated with individual blood proteins, their mixture, and diluted human plasma. The concentration of adsorption sites was calculated from the sizes of protein molecules, assuming the formation of a monolayer. For the titrations with the protein mixture and diluted plasma, the concentration of titrant was an estimate, limiting the accuracy of thermodynamic parameters. The particles with grafted polymer brushes showed negative xi-potentials similar to the blood proteins and their interactions occurred against the Coulomb forces. Two cases of exothermic hydrophobic and endothermic polar interactions were distinguished. The strength of adsorption, expressed with the affinity constant Ka, was dependent on brush composition and temperature. The adsorption of proteins from blood plasma was always exothermic and, therefore, the dominating hydrophobic interactions were assumed.

Modern biomedical technologies predict the application of materials and devices that not only can comply effectively with specific requirements, but also enable remote control of their functions. One of the most prospective materials for these advanced biomedical applications are materials based on temperature-responsive polymer brush coatings (TRPBCs). In this review, methods for the fabrication and characterization of TRPBCs are summarized, and possibilities for their application, as well as the advantages and disadvantages of the TRPBCs, are presented in detail. Special attention is paid to the mechanisms of thermo-responsibility of the TRPBCs. Applications of TRPBCs for temperature-switchable bacteria killing, temperature-controlled protein adsorption, cell culture, and temperature-controlled adhesion/detachment of cells and tissues are considered. The specific criteria required for the desired biomedical applications of TRPBCs are presented and discussed.