Random Copolymer Poly Research Articles

PH‐sensitive size/surface charge‐adaptive quaternary ammonium salt copolymer micelles for antibiofilm activity against Staphylococcus aureus

AbstractThe low penetration of antibacterial materials within biofilms results in a 1000‐fold decrease in bactericidal efficiency, complicating the complete removal of biofilms and potentially leading to persistent and recurrent bacterial infections that significantly impact human health. In this study, we present a multifunctional pH‐responsive antibacterial material based on random copolymers poly(dimethylaminoethyl methacrylate decyl ammonium bromide‐co‐polyethylene glycol methacrylate) copolymer (PQACs10‐co‐PEGMA10). The PQACs10‐co‐PEGMA10 copolymers could self‐assemble into micelles in selective solvent water. With the stealth function of polyethylene glycol (PEG), the PQACs10‐co‐PEGMA10 micelles can rapidly penetrate biofilms in a physiological environment and exhibit excellent antibacterial activity by exposing the quaternary ammonium salt (QACs) in an acidic microenvironment to eliminate biofilm. Furthermore, PQACs10‐co‐PEGMA10 micelles were applied as coatings using a dropwise method. The PEG chain formed hydration layer and the QACs chain for sterilization can hinders bacterial adhesion and proliferation, thereby preventing biofilm formation. The results show that the minimal inhibit concentration values and minimum biofilm eradication concentrations of the PQACs10‐co‐PEGMA10 micelles against Gram‐positive Staphylococcus aureus were 64 and 128 μg/mL, respectively. The antifouling and antibacterial rates of micelle coating against S. aureus were more than 99.99%. Taken together, the pH‐responsive PQACs10‐co‐PEGMA10 micelles demonstrate a good ability to clear and prevent biofilms, holding promise for complete biofilm removal and a reduction in biofilm‐related infections.

Synthesis of full bio‐based, fast degradable, and high strength copolyesters: Poly(butylene succinate‐sebacicate‐salicylicate‐malicate)

AbstractThe presence of petroleum‐based monomers in the backbone of poly(butylene succinate‐co‐adipate) (PBSA) restricts its application in light of increasingly stringent environmental regulations. In this study, a novel full bio‐based biodegradable random copolymer poly(butylene succinate‐sebacicate‐salicylicate‐malicate) (PBSSeSa‐c‐M) was designed and synthesized. The comprehensive study encompassed the structural alterations, properties, and degradation resulting from the inclusion of salicylicate sebacicate and malicate units. The incorporation of salicylic acid effectively enhanced the tensile modulus of the copolymer, due to the effect of rigid benzene ring. Meanwhile, the addition of sebacic acid regulated the degradation rate. The introduction of malic acid significantly improved the rheological properties, endowing the copolymer with exceptional processability. The obtained high molecular weight PBSSeSa‐c‐M exhibited outstanding film‐blowing processability with an intrinsic viscosity of 1.58 dL/g and melt flow rate of 7.34 g/10 min. The tensile modulus reaches 235.43 MPa that is comparable to commercial PBSA. Besides, the degradation of PBSSeSa‐c‐M reaches 18.92% over 4 weeks, far higher than that of PBSA. In conclusion, this work provides a design and synthesis for a new kind of biodegradable copolyester that satisfies the requirement of rapid degradation in single‐use plastics.

Hierarchical structure of poly(ε-caprolactone) crystals on its copolymer poly(l-lactide-co-ε-caprolactone) fibers

In crystallization, heterogeneous structures of copolymers are employed to establish a hierarchical architecture comprising two polymers, this typically occurs on the surface of block copolymers or blended polymers. While hierarchical structures in block copolymer fibers are well-established and widely utilized, achieving a regular hierarchical structure on random copolymer fibers is both meaningful and challenging. Here, we present a case of forming a hierarchical structure on the surface of the random copolymer poly(L-lactide-co-caprolactone) (PLCL)fibers. The (ε-caprolactone)(CL) polymer chain segments of the random copolymer are released on the surface of the modified copolymer fiber using sodium hydroxide. Subsequently, poly(ε-caprolactone)(PCL) forms a shish kebab-like crystalline structure under the guidance of the CL segments. The CL segments act as crystalline precursors to induce the formation of heterogeneous PLCL/PCL shish kebab structures. The variation of CL segments on the fiber changes with modification time, leading to the formation of crystalline lamellae of different sizes, which had been confirmed by characterization techniques such as scanning electron microscope (SEM), 1H NMR, X-ray photoelectron spectra (XPS), differential scanning calorimetry (DSC), etc. The implementation of this heterogeneous structure provides possibilities for the implementation of hierarchical structure in random copolymers.

Synthesis and investigation of sustainable long-chain branched poly(lactic acid-r-malic acid) copolymer as toughening agent for PLA blends

Poly(lactic acid) (PLA) is the most promising candidate for biobased and biodegradable plastic which combines biocompatibility, renewability as well as excellent processability. However, toughening is still needed for PLA as to obtain materials suitable for broader applications. In this work, long-chain branched random copolymers poly(lactic acid-r-malic acid) (PMLA) were synthesized based on bio-resourced lactic acid (LA) and malic acid (MA) through polycondensation as toughening agent for PLA. The chemical structures of PMLA were characterized by 1H NMR and 1H–13C HSQC analysis. In the PLA and PMLA blends, PMLA has apparent effect on the crystallinity of PLA and the blends show a great increase of elongation at break to over 300 % even at low PMLA content of 2%wt. Furthermore, the thermal properties of the blend are characterized through DSC and the micro-structure investigated through Positron annihilation lifetime spectroscopic (PALS) technique. PMLA with long-chain branched topology shows an excellent capability in the toughening of PLA and maintains the total biodegradability of the resultant blend at the same time, that is critical for environment-friendly materials.

Influences of probe shape and surface roughness on tack properties measured by the probe tack test and characterization of crosslinked polyacrylic pressure‐sensitive adhesives

AbstractFor a probe tack test for a pressure‐sensitive adhesive (PSA) under the conditions of light contact pressure and short contact time, probes with shapes and surface roughnesses suitable to achieve better wettability were investigated. A smooth, polished probe that became slightly convex at its center was found to be superior to flat‐ended. High surface roughness decreased tack. Debonding observations showed that fibrillation started from the probe edge and extended to the center. The fibril grew, without peeling, until the peak of the force–displacement curve was reached. After the peak, the fibril growth and peeling advanced simultaneously. The fibrillation was important to tack development. The test conditions necessary to observe the deformation behavior of PSA tape with sufficient interfacial adhesion were investigated. The system was preheated at 60°C for 1 h after the probe and PSA tape contacted each other, and was then cooled. The PSA performance of crosslinked random copolymers poly(n‐butyl acrylate‐acrylic acid) (A) and poly(2‐ethylhexyl acrylate‐acrylic acid) (B) were compared. A shoulder formed by fibrillation after the peak in the force–displacement curve was observed only for B. Copolymer B exhibited better interfacial adhesion and deformability. The preheating method was found to be useful for characterizing PSAs.

Surface encapsulating UV filters based on self-assembly of an amphiphilic random copolymer by miniemulsion polymerization

A nanoparticles encapsulating UV filters were prepared by miniemulsion polymerization, in which methyl methacrylate (MMA) as the monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker. Scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS) confirmed that the amphiphilic random copolymers poly (styrene-co-methacrylic acid) P(St-co-MAA) not only acted as the stabilizer but also self-assembled on the surface of the P(MMA-EGDMA) polymers. During the miniemulsion polymerization, most UV filters were encapsulated in the P(St-co-MAA) self-assembly aggregates on the surface of nanoparticles, giving the nanoparticles a raspberry-like structure. As the mass ratio of P(St-co-MAA) to MMA and EGDMA at 1.0, the encapsulation efficiency of UV filters was 69.85%, whereas 70.7% of UV filters were located in the P(St-co-MAA) self-assembly layer. The leakage of UV filters from the raspberry-like nanoparticles was negligible after continuous stirring in isopropyl myristate (IPM) for 24 h. The sun protection factor (SPF) and UVA Protection Factor (UVAPF) value of sunscreen formulation incorporated with the raspberry-like nanoparticles could reach 58.8 and 6.82, respectively. It enhanced UV protection more efficiently than the nanoparticles with a smooth surface.

Self-Aggregation in Aqueous Media of Amphiphilic Diblock and Random Block Copolymers Composed of Monomers with Long Side Chains.

Amphiphilic diblock copolymers and hydrophobically modified random block copolymers can self-assemble into different structures in a selective solvent. The formed structures depend on the copolymer properties, such as the ratio between the hydrophilic and the hydrophobic segments and their nature. In this work, we characterize by cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS) the amphiphilic copolymers poly(2-dimethylamino ethyl methacrylate)-b-poly(lauryl methacrylate) (PDMAEMA-b-PLMA) and their quaternized derivatives QPDMAEMA-b-PLMA at different ratios between the hydrophilic and the hydrophobic segments. We present the various structures formed by these copolymers, including spherical and cylindrical micelles, as well as unilamellar and multilamellar vesicles. We also examined by these methods the random diblock copolymers poly(2-(dimethylamino) ethyl methacrylate)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (P(DMAEMA-co-Q6/12DMAEMA)-b-POEGMA), which are partially hydrophobically modified by iodohexane (Q6) or iodododecane (Q12). The polymers with a small POEGMA block did not form any specific nanostructure, while a polymer with a larger POEGMA block formed spherical and cylindrical micelles. This nanostructural characterization could lead to the efficient design and use of these polymers as carriers of hydrophobic or hydrophilic compounds for biomedical applications.

Humidity-Responsive Antimicrobial Membranes Based on Cross-Linked Copolymers Functionalized with Ionic Liquid Moieties.

Humidity-responsive materials have attracted increasing attention for their potential use in various applications, e.g., sensors, soft robotics, and human-machine interfaces. Much effort has been focused on the use of ionic liquids for the construction of humidity-responsive sensors; yet, not enough attention has been paid on the susceptibility of the used poly(ionic liquid)s to microorganisms. This is especially relevant to the wide use of the polymers for biomedical applications, e.g., wearable body-condition sensors or healthcare control systems. We herein describe the development of dual functional, self-standing, monolayer antimicrobial membranes derived from cross-linked copolymers functionalized with ionic liquids. In a first step, random copolymers of poly(4-vinylbenzyl N-alkyl imidazolium chloride-co-acrylic acid), P(VBCImCn-co-AA20), were synthesized bearing aliphatic chains of different lengths (where n = 1, 4, 8, 12, 16 carbon atoms) to investigate the effect of hydrophobicity/hydrophilicity on the humidity-responsive properties of the copolymer and its antimicrobial activity. The aforementioned copolymers were later blended with the complementary reactive copolymers of poly(cetyl trimethylammonium 4-styrene sulfonate-co-glycidyl methacrylate), P(SSAmC16-co-GMA20), to provide highly stable films and coatings through thermal cross-linking. The membrane P(VBCImC12-co-AA20)/P(SSAmC16-co-GMA20) with a molar ratio of 3:1 (mol AA/mol GMA) exhibited immediate and high response to moisture through folding or flipping motions when placed on a wet filter paper or on the palm of a hand. The inhibition of growth for selected bacterial species (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) on the copolymer membranes was dependent on the length of the imidazolium alkyl chain and the species. Additionally, in the case of the cross-linked P(VBCImCn-co-AA20)/P(SSAmC16-co-GMA20) membranes, the overall efficacy was very high against all microorganisms tested, which, combined with their high humidity responsiveness, enables their potential application.

LCST/UCST transition of acrylate copolymer with cosolvency behaviors in alcohol aqueous solutions

Though the mechanism of temperature-induced lower critical solution temperature (LCST) in water is clear for the classic homopolymer poly(N-isopropylacrylamide) (PNIPAM), the LCST of other homopolymer or copolymer remains to be understood. In this work, a novel random copolymer poly(2-hydroxyethyl-co-methyl acrylate) (P(HEA-co-MA)) was prepared. The LCST of the copolymer P(HEA-co-MA) can vary from 11 °C to 65 °C by adjusting flexibly the ratio of the two monomers, showing a broad tunable range. The experimental results showed that the balance of hydrogen bond bridge formed by P(HEA-co-MA) in water and the hydrophobic interaction between polymers can cause the LCST transition of P(HEA-co-MA). An interesting observation is that the sharp phase transition (cosolvency) of P(HEA-co-MA) exists when a rather small amount of alcohol or water is added in polymer solutions at constant temperatures. Moreover, it was found that the increase of LCST is correlated with the increase of alcohol concentration in the water-rich regime, but the decrease of upper critical solution temperature (UCST) is related to the increase of water concentration in the alcohol-rich regime. This work shed light on the understanding of cosolvency by studying the solution behavior of copolymer P(HEA-co-MA) in mixed solvents, which can be of interest for the design of stimuli-responsive polymer materials by variation in solvent composition.

Impact of hydrogen bonding pendant groups in polymer grafted nanoparticles on interlayer adhesion and mechanical properties in material extrusion printing

The addition of nanoparticles or copolymer grafted nanoparticles (CPGNPs) to polymeric matrices greatly improves thermomechanical properties of the resulting nanocomposite, but corresponding studies of nanocomposite systems created by 3D printing are few, especially in the realm of functional polymeric materials. Here we describe how silica nanoparticle-grafted, random copolymers of poly(methyl methacrylate-random-2-uriedo-[1H]-pyrimidinone methacrylate) (P(MMA-r-UPyMA) dramatically increases the mechanical properties of poly(methyl methacrylate) (PMMA) based nanocomposite specimens created by melt extrusion printing. Most notably, when these novel CPGNPs are combined with PMMA matrix chains via a solution-based process, printed specimens containing only 0.5 wt% additive show significant increases in Young’s modulus (90%), storage modulus (93%), tensile modulus (148%) and ultimate tensile strength (110%). These improvements are ascribed to strengthening of adhesion across interfaces due to multi-point hydrogen bonding between UPyMA groups, the reinforcement effect of the P(MMA-r-UPyMA)-grafted silica nanoparticles, as well as hydrogen bonding interactions and entanglements between graft and matrix chains. Imaging of fracture surfaces after tensile testing reveals that in comparison to nanocomposites created by simple mechanical mixing of solids, the solution-casting process improves the dispersion of nanoparticles and reduces the void spaces between printed beads. These studies demonstrate that introducing functionality into polymer grafts, such as hydrogen bonding interactions, and intimate mixing of polymer-modified nanomaterials can greatly improve interlayer adhesion and mechanical properties, thereby advancing this method of polymer additive manufacturing.

Controlled and effective ring-opening (co)polymerization of rac-lactide, ε-caprolactone and ε-decalactone by β-pyrimidyl enolate aluminum complexes

A series of β-pyrimidyl enolate aluminum complexes (1–6) were found to promote controlled and living ROP of rac-LA, ε-CL, and ε-DL. Six well-defined diblock copolymers and the perfect random copolymer poly(l-LA-r-CL) were successfully synthesized.

Environmentally Stable, Stretchable, Adhesive, and Conductive Organohydrogels with Multiple Dynamic Interactions as High-Performance Strain and Temperature Sensors.

Nowadays, with the rapid development of artificial intelligence, conductive hydrogel-based sensors play an increasingly vital role in health monitoring and temperature sensing. However, the perfect integration of the environmental stability and applied performance of the hydrogel has always been a challenging and significant problem. Herein, we report an environmentally tolerant, stretchable, adhesive, self-healing conductive gel through multiple dynamic interactions in the water/glycerol/ionic liquids medium, which can be used as a high-performance strain and temperature sensor. The random copolymer poly(acrylic acid-co-acetoacetoxyethyl methacrylate) interacts with the branched poly(ethylene imine) (PEI) and Zr4+ ions via the dynamic covalent enamine bonds, coordinations, and electrostatic interactions to improve stretchable (1300%), compressible, fatigue-resistant (1000 cycles at 50% strain), and self-healing performance (95%, 24 h). The combination of water/glycerol/ionic liquids imparts the resulting gel with excellent electrical conductivity, anti-drying, and anti-freezing performance. By means of the above excellent performance, the gel could be used as the flexible strain or pressure sensor with high sensitivity and stability for the detection of the movement, expression, handwriting, pronouncing, and electrocardiogram (ECG) signals in various models. Meanwhile, the resulting gel can be assembled as the temperature sensor to trace the change of temperature accurately and steadily, which has a wide operating window (0 to 100 °C), an ultralow detection limit (0.2 °C), and high sensitivity (2.1% °C-1). It is believed that the strategy for the multifunction and high-performance gel will blaze a new trail for the smart device in health management, temperature detection, and information transmission under various environmental conditions.

Fabricating switchable Pickering emulsions by dynamic covalent copolymer amphiphiles

In this work, amphiphilic copolymers D-An based on the dynamic imine bonds were generated in-situ in the aqueous solutions by two water-soluble precursors, the random copolymer poly(N-(2-methacryloylxyethyl)-random-poly(4-(formaldehyde) phenyl methacrylate) (PNMP83-co-PBFMA4, Precursor D) and alkylamines (Precursor An, n represents the carbon number in the alkyl chain that is ranging from 4 to 10). Amphiphiles D-An formed micelles spontaneously in the aqueous solutions, which were studied by the surface tension and cryogen-transmission electron microscopy (cryo-TEM) measurements. Moreover, the CO2/N2 responsive micellization of D-An due to the reversible formation and breaking of the dynamic imine bond (-CH=N-) was confirmed by the nuclear magnetic resonance (NMR) measurements. Accordingly, the emulsification of dynamic covalent amphiphilic copolymers D-An was studied in detail. O/W Pickering emulsions with excellent stability were commonly generated by employing D-An as emulsifiers regardless of n and the nature of oil employed, which was significantly different from the weak emulsification of either precursor D or precursor An. The synergistic emulsification of D-An monomers and micelles was proved to be the major cause as evidenced by the confocal laser scanning microscopy (CLSM) method. Noticeably, the abundant alkylamines were also advantageous in stabilizing emulsions. Attributing to the stimuli-responses of amphiphiles D-An to CO2/N2, the stability of Pickering emulsions could be reversibly controlled by CO2/N2 as well.

Core-Coordinated Elliptic Polymer Nanoparticles Loading Copper(II) and Chlorambucil for Cooperative Chemodynamic/Chemotherapy.

Chemodynamic therapy (CDT) reflects an innovative cancer treatment modality; however, to enhance its relatively low therapeutic efficiency, rational combination with extra therapeutic modes is highly appreciated. Here, core-coordinated amphiphilic, elliptic polymer nanoparticles (Cu/CBL-POEGEA NPs) are constructed via the self-assembly of a glutathione (GSH)-responsive polymer-drug conjugate, bearing side-chain acylthiourea (ATU) motifs which behave as ligands capable of coordinating Cu(II), such a design is featured by combined chemo (CT)/CDT with dual GSH depletion collectively triggered by the Cu(II) reduction reaction and disulfide bond breakage. To do so, an amphiphilic random copolymer poly[oligo(ethylene glycol)ethyl acrylate-co-thiourea] [P(OEGEA-co-ATU)] is synthesized, followed by conjugation of chlorambucil (CBL) to ATU motifs linked via a disulfide bond, thus yielding the targeted P[OEGEA-co-(ATU-g-CBL)]. In such a system, hydrophilic POEGEA serves as the biocompatible section and ATU motifs coordinate Cu(II), resulting in core-coordinated elliptic Cu/CBL-POEGEA NPs. Benefitting from the GSH-induced reduction reaction, Cu(II) is converted into Cu(I) and subsequently react with endogenous H2O2 to create •OH, realizing GSH-depletion-promoted CDT. Additionally, the disulfide bond endows GSH-responsive CBL release and provokes further GSH decline, finally realizing combined CDT/CT toward enhancing antitumor outcomes, and in vitro as well as in vivo studies indeed reveal remarkable efficacy. Such a system can provide valuable advantages to create novel nanomedicines toward cascade antitumor therapy.

Enhanced Electrochemical Performance of NCM811 Cathodes with Functionalized PVDF Graft Copolymer Binders

Nickel-rich Li(Ni x Co y Mn1–x–y O2) (x ≥ 0.6) (NCM) cathodes are regarded as the predominant cathode materials for next-generation Li-ion batteries due to their high specific energy density. However, undesired structural disruption and thermal instability were observed with the increase of Ni content e.g. Ni0.8Co0.1Mn0.1(NCM811), which are often attributed to the transition metal (TM) ion dissolution, phase change, oxygen release and microcracks formed on the secondary particles during cycling. Therefore, the rapid capacity loss and poor capacity retention have hindered the successful practical applications for NCM811 cathodes. To solve these abovementioned problems, many strategies have been proposed. One of most effective way is to design and explore functional and novel polymer binder materials. Although poly(vinylidene fluoride) (PVDF), as the benchmark binder in battery community, has been widely used for decades, lacking of functional groups and poor chemical interactions with the active particles makes it no longer the optimal choice for more challenging cathodes.Herein, to explore the possibilities and broaden the range of functional polymers for boosting the performance of NCM811 cathodes, we propose grafting from poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) to obtain PVDF-based polymers with a comb-like architecture, where the PVDF-CTFE was chosen as a substrate backbone to provide the initiating sites for further modification. Atom transfer radical polymerization (ATRP), the controlled radical polymerization technique was used to obtain well-controlled grafted chains with low dispersity and desired length and architecture. A random copolymer of poly(ethylene glycol) methyl ether acrylate and poly(tert-butyl acrylate) (PEGMEA-co-PtBA) was first grafted from the PVDF-CTFE backbone, then after hydrolysis of PtBA to poly(acrylic acid) (PAA), the PVDF-CTFE-g-PEGMEA-co-PAA graft copolymers were obtained. Benefiting from the ethylene oxide conductive segments in PEGMEA, the Li ion diffusion and transport was significantly improved. The chelation of TM ions to -COOH groups from PAA would effectively mitigate the TM dissolution and prevent phase transition of NCM811. To test the electrochemical performances of NCM811 cathodes prepared with the designed polymer binder, PVDF and PVDF-CTFE were compared as the control groups in this study. The rate performance of the Li|NCM811 cells showed that PVDF-CTFE-g-PEGMEA-co-PAA binder gave comparable discharge capacities to PVDF and PVDF-CTFE at 0.1C-2C (Figure 1a), however, under 4C with faster charging/discharging, the discharge capacities of PVDF-CTFE-g-PEGMEA-co-PAA were much higher than the two control groups. When increasing the NCM811 weight ratio from 85 wt% to 93 wt%, where the contribution from the conductive carbon is less, the differences were even more significant (Figure 1b). PVDF-CTFE-g-PEGMEA-co-PAA delivered higher capacity at all rates, especially at 2C and 4C, suggesting faster Li ion transport and enhanced electronic properties in the cathodes. Figure 1. Rate performance of Li|NCM811 cells with binder PVDF (grey), PVDF-CTFE (orange) and PVDF-CTFE-g-PEGMEA-co-PAA (green) in the voltage range of 2.9–4.3 V using NCM811/carbon black/binder weight ratio of a) 85/10/5 and b) 93/4/3. Figure 1

Inspired by mussel: biomimetic polyelectrolyte complex coacervate adhesive initiates a connection through water exchange

Here the authors report a versatile and strong underwater adhesive that was inspired by the chemical features of mussel foot proteins. A random copolymer (poly(N-(3,4-dihydroxyphenethyl)methacrylamide-co-methacryloxyethyltrimethyl ammonium chloride-co-acrylamide) (PDMA)–Tf2N) was prepared that contained side-chain catechol groups and quaternary ammonium cations that were ion-paired with bis(trifluoromethane-sulfonyl)imide anion (Tf2N−). After dissolving PDMA–Tf2N and poly(acrylic acid) in dimethyl sulfoxide, a polyelectrolyte complex coacervate adhesive (P2) could be formed, which could be triggered through solvent exchange. P2 exhibited outstanding underwater shear strength to various substrate surfaces. After a critical curing time (t s = 10 min), the adhesion strength of P2 to glass increased sharply up to 187.298 kPa (t s = 40 min).

PH and thermo dual-sensitive copolymers with fluorescent properties grafted mesoporous silica SBA-15 via metal-free ATRP

Well-defined pH and thermo dual-sensitive random copolymers poly(2-(diethylamino)ethyl methacrylate)–co-poly(N-isopropylacrylamide)–co-Eu complex with fluorescent properties grafted mesoporous silica SBA-15 (SBA-15-g-PDEAEMA-co-PNIPAM-co-Eu complex) was prepared by surface-initiated metal-free atom transfer radical polymerization (metal-free ATRP). The ATRP initiator 2-bromoisobutyryl bromide (BIBB) was immobilized on the SBA-15 surfaces followed by metal-free ATRP of 2-(diethylamino)ethyl methacrylate) (DEAEMA), N-isopropylacrylamide (NIPAM) and Eu complex. The hybrid material was characterized by fourier transform infrared spectroscope (FT-IR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscope (AFM), thermal gravimetric analysis (TGA), N2 adsorption/desorption measurements, X-ray powder diffraction (XRD), Fluorescence spectrum and Nanoparticle Size-Zeta potential analyzer. The results showed that the SBA-15-g-PDEAEMA-co-PNIPAM-co-Eu complex hybrid material has been prepared successfully. The pore size, pore volume and specific surface area of SBA-15 decreased after grafting of the copolymers, but the ordered structure of SBA-15 pore still remained. The fluorescence testing suggested that the hybrid material had good fluorescence characteristics. The pH and temperature sensitivity analysis suggested that the hybrid material dispersion was good under low temperature and acid condition because the polymer chains stretched.

Single Copolymer Chain‐Templated Synthesis of Ultrasmall Symmetric and Asymmetric Silica‐Based Nanoparticles

AbstractUltrasmall silica‐based nanoparticles (SNPs) are attractive for application in many fields, but existing synthetic approaches show limited control over the size and morphology of these SNPs. This study describes a general single copolymer chain‐mediated strategy for the scalable synthesis of highly monodispersed symmetric and asymmetric SNPs with sub‐50 nm diameter. Random copolymers of poly(acrylic acid‐r‐styrene) intramolecularly collapse into ultrasmall single‐chain nanoparticles and serve as seeds to template the hydrolysis of silica precursors to produce uniform SNPs. It is shown in experiments and simulations that the composition and random architecture of the copolymers are crucial to the formation of ultrasmall seeds and the uniform deposition of silica. Furthermore, tailoring the architecture of copolymers can be used to produce ultrasmall asymmetric Janus‐like and dumbbell‐like SNPs with well‐defined polymer and silica domains. This study paves a new route to the scalable production of ultrasmall SNPs with tailored morphologies.

The stabilization of ultrafiltration membrane blended with randomly structured amphiphilic copolymer: Micropollutants adsorption properties in filtration processes

In this study, a blend membrane consisting of polyvinylidene fluoride (PVDF) and tertiary amine containing random copolymer poly(methyl methacrylate-r-dimethylamino-2-ethyl methacrylate) (P(MMA-r-DMAEMA)) was fabricated and utilized as an adsorptive membrane for micropollutants (anionic dye and heavy metal ions) removal from aqueous solutions. Cross-linking the random copolymer by p-xylylene dichloride (XDC) produced the membrane with improved copolymer retention ratio and stability, while slightly variated physicochemical properties. Besides, the fluxes of crosslinked blend membranes dramatically increased from 0.7 ± 0.1 L/(m2h) to 118.6 ± 5.9 L/(m2h). Then the present blend membrane was carried out adsorption and filtration experiments to investigate the influence of various of operation parameters including initial solution pH value, contacting time, initial solution concentration, and recycling efficiency on micropollutants removal. The experimental results showed that the removal of the anionic dyes and heavy metal ions on this tertiary amine containing blend membrane was a pH-dependent process with the maximum adsorption capacity at the initial solution pH of 3.5 for anionic dyes and 6.0 for metal ions, respectively. The membrane showed highly efficient capture of sunset yellow (above 99%). Meanwhile, the captured sunset yellow was recovered and concentrated with a small volume of alkaline solutions at pH 10.0, which simultaneously regenerated the membrane for its reuse. In a 3-cycle capture-recovery test, the membrane demonstrated a high sunset yellow recovery ratio and a volumetric concentration ratio as high as 400%. Our study provides an alternative strategy for functionalized membrane fabrication, micropollutants removal and recovery.

Multiple strategies to control the hydrophilic-hydrophobic balance of P(DMA-co-DMAEMA-co-QDMAEMA) coatings.

The regulation of the hydrophilic-hydrophobic balance of polymers has an important influence not only on their aggregation behavior in aqueous solution, but also on their adhesion properties on the surface of substrates and the applications of the modified surfaces. Based on this, a random copolymer poly(dopamine methacrylamide-co-2-(dimethylamino)ethyl methacrylate) (P(DMA-co-DMAEMA)) was synthesized as a starting polymer to generate P(DMA-co-DMAEMA-co-QDMAEMA) (PDDQ) derivatives by a programmable quaternization of the DMAEMA precursor. By adjusting the pH or temperature, both the aggregation behavior in aqueous solutions and the surface adhesive behavior on the substrate surfaces of PDDQ copolymers were regulated due to the hydrophilic-hydrophobic balance. Specifically, the surface adsorption of PDDQ copolymers on surfaces was enhanced by the increased hydrophobicity of PDDQ. Stainless steel meshes (SSM) modified with the PDDQ0 copolymer without quaternization showed a superoleophobicity in acidic aqueous media, which endowed it with improved oil-water separation performance. In addition, the hydrophilic-hydrophobic balance of PDDQs and their coatings could also be tuned by changing the ratio of DMAEMA to QDMAEMA in the copolymer. From PDDQ0 to PDDQ100, by increasing the hydrophilic QDMAEMA component of PDDQ copolymers, anti-protein properties and oil/water separation efficiency of the modified surfaces were also enhanced gradually. The results provided a reference for designing P(DMA-co-DMAEMA-co-QDMAEMA) coatings in different application environments.