Double Hydrophilic Copolymers Research Articles

Customizing Cerium Oxide Particle Synthesis with Hybrid Polyion Complex Templates for Enhanced Oxidation Performance in Photo-Fenton Processes.

Hybrid poly-ion complexes were synthesized through the complexation of a double hydrophilic copolymer with Ce(III) ions. These colloids act as reservoirs for cerium ions, enabling the synthesis of cerium-based Prussian blue nanoparticles with a cubic structure, a narrow size distribution around 100 nm, and good colloidal stability in water. Upon high-temperature calcination, these nanoparticles are transformed into a cerium/iron-based metal oxide catalyst (CeO2/Fe2O3). The resultant composite catalyst demonstrates superior performance in the photo-Fenton oxidation of methylene blue pollutants, achieving a conversion efficiency that rivals other metal-based oxides and cerium-based catalysts.

Dense Monolayer Network Structures of Double Hydrophilic Hyperbranched Copolymers at the Air/Water Interface.

Influences of subphase pH and temperature on the interfacial aggregation behavior of two double hydrophilic hyperbranched copolymers of poly[oligo(ethylene glycol) methacrylate-co-(2-diisopropylamino)ethyl methacrylate] (P(OEGMA-co-DIPAEMA)) at the air/water interface are studied by the Langmuir film balance technique. Morphologies of their Langmuir-Blodgett (LB) films are characterized by atomic force microscopy (AFM). At the interface, P(OEGMA-co-DIPAEMA) copolymers tend to form a dense network structure of circular micelles composed of branching agent-connected carbon backbone cores and mixed shells of OEGMA and DIPAEMA segments (pendant groups). This network structure containing many honeycomb-like holes with diameters of 6-8nm is identified for the first time and clearly observed in the enlarged AFM images of their LB films. Under acidic conditions, surface pressure versus molecular area isotherms of the two copolymers in the low-pressure region show larger mean molecular area than those under neutral and alkaline conditions due to the lack of impediment from DIPAEMA segments. Upon further compression, each isotherm exhibits a wide pseudo-plateau, which corresponds to OEGMA segments being pressed into the subphase. Furthermore, the isotherms under neutral and alkaline conditions exhibit the lower critical solution temperature behavior of OEGMA segments, and the critical temperature is lower when the hyperbranched copolymer contains higher OEGMA content.

Tailoring Hydrogen-Bonding Strategy for Sequence-Dependent and Thermo/pH Dual-Responsive Clusteroluminescence.

Rational design of monomer sequence for desired properties is challenging. This study investigates the effect of monomer distribution of double hydrophilic copolymers (DHCs) with electron-rich units on cluster triggered emission (CTE) capacity. By means of combining latent monomer strategy, reversible addition fragmentation chain transfer (RAFT) polymerization and selective hydrolysis technology, the random, pseudo di-block and the gradient DHCs consisting of pH-responsive polyacrylic acid (PAA) segments and thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) segments were successfully synthesized in a controlled manner. Moreover, the gradient DHCs showed a tremendously increased luminescent intensity due to the distinct hydrogen-bonding interaction compared to random and pseudo di-block DHCs. To the best of our knowledge, this is the first reported the direct correlation between luminescent intensity and sequence structure of non-conjugated polymer. Meanwhile, thermo and pH dual-responsive clusteroluminescence could be easily performed. This work demonstrates a novel and facile method to tailor the hydrogen-bonding for the stimuli-responsive light-emitting polymers.

Double hydrophilic copolymers - synthetic approaches, architectural variety, and current application fields.

Solubility and functionality of polymeric materials are essential properties determining their role in any application. In that regard, double hydrophilic copolymers (DHC) are typically constructed from two chemically dissimilar but water-soluble building blocks. During the past decades, these materials have been intensely developed and utilised as, e.g., matrices for the design of multifunctional hybrid materials, in drug carriers and gene delivery, as nanoreactors, or as sensors. This is predominantly due to almost unlimited possibilities to precisely tune DHC composition and topology, their solution behavior, e.g., stimuli-response, and potential interactions with small molecules, ions and (nanoparticle) surfaces. In this contribution we want to highlight that this class of polymers has experienced tremendous progress regarding synthesis, architectural variety, and the possibility to combine response to different stimuli within one material. Especially the implementation of DHCs as versatile building blocks in hybrid materials expanded the range of water-based applications during the last two decades, which now includes also photocatalysis, sensing, and 3D inkjet printing of hydrogels, definitely going beyond already well-established utilisation in biomedicine or as templates.

Micellization through complexation of oppositely charged diblock copolymers: Effects of composition, polymer architecture, salt of different valency, and thermoresponsive block

AbstractThe structural and electrical characteristics of polyelectrolyte complex micelles (PCMs) formed by mixing of oppositely charged double hydrophilic copolymers are studied by means of molecular dynamics simulations. In mixtures of linear diblock copolymers we found that the preferential aggregation number Np of PCMs is a universal function of the ratio γ± of the total positive to total negative charges of the mixture. The addition of divalent salts ions induces a secondary micellization. In mixtures of copolymers bearing a common neutral thermoresponsive block, micelles with contracted corona consisting of thermoresponsive blocks and complex polyelectrolyte core are formed at low salt concentration and temperature far away the biphasic regime. At high salt concentration and temperature in the biphasic regime, reversed micelles are obtained. In equimolar mixtures of linear copolymers with miktoarm stars we found that Np of PCMs decreases as the number of charged branches of miktoarm copolymer increases. The shape of micelles progressively changes from spherical to worm‐like with the increase of number of branches of miktoarm copolymers. Our findings are in full agreement with existing experimental and theoretical predictions and provides new and additional insights.

Optical Sensing of Humidity Using Polymer Top-Covered Bragg Stacks and Polymer/Metal Thin Film Structures.

Thin films with nanometer thicknesses in the range 100–400 nm are prepared from double hydrophilic copolymers of complex branched structures containing poly(N,N-dimethyl acrylamide) and poly(ethylene oxide) blocks and are used as humidity sensitive media. Instead of using glass or opaque wafer for substrates, polymer thin films are deposited on Bragg stacks and thin (30 nm) sputtered Au–Pd films thus bringing color for the colorless polymer/glass system and enabling transmittance measurements for humidity sensing. All samples are characterized by transmittance measurements at different humidity levels in the range from 5% to 90% relative humidity. Additionally, the humidity induced color change is studied by calculating the color coordinates at different relative humidity using measured spectra of transmittance or reflectance. A special attention is paid to the selection of wavelength(s) of measurements and discriminating between different humidity levels when sensing is performed by measuring transmittance at fixed wavelengths. The influence of initial film thickness, sensor architecture, and measuring configuration on sensitivity is studied. The potential and advantages of using top covered Bragg stacks and polymer/metal thin film structures as humidity sensors with simple optical read-outs are demonstrated and discussed.

Nanoparticulate delivery of irinotecan active metabolite (SN38) in murine colorectal carcinoma through conjugation to poly (2-ethyl 2-oxazoline)-b-poly (L-glutamic acid) double hydrophilic copolymer

SN-38 is the active metabolite of irinotecan, an FDA-approved chemotherapeutic agent indicated for colorectal carcinoma, which would not be clinically applicable due to its very poorly soluble and hydrolytic degradation properties. To overcome these limitations, it was proposed to conjugate SN38 to residing carboxylic acid residues in poly (2-ethyl 2-oxazoline) block poly (L-glutamic acid), inducing nano-assembly in aqueous medium. Following a series of reactions including poly (2-ethyl oxazoline) macro-initiated ring opening polymerization of N-carboxyanhydride, deprotection of benzyl group and chemical conjugation of SN38 via biodegradable ester linkage, the as-synthesized product was characterized by dynamic light scattering, ζ potential and transmission electron microscopy. The resulting particles presented about 90% loading efficiency with a mean size of 90 nm. Upon incubation with colorectal carcinoma CT26 cell line, higher association of SN-38 fluorescence and significantly more specific cytotoxicity was noticed for the SN38 conjugated particles than free drug. Therapeutic applicability of the as-synthesized product was evaluated in CT26 allograft tumor model in BALB/c mice, showing superior efficiency of the SN38 conjugated particles particularly in tumors with sizes larger than 200 mm3 than parent irinotecan and reduced mortality rate by 2.5 times. Conclusively, the poly (2-ethyl 2-oxazoline) decorated nano-conjugates of poly (L-glutamic acid) and SN38 can be regarded as a novel and potentially efficient drug delivery system for advanced colorectal carcinoma.

Self-Assembly of a Thermally Responsive Double-Hydrophilic Copolymer in Ethanol-Water Mixtures: The Effect of Preferential Adsorption and Co-Nonsolvency.

Lower alcohols can induce a combined collapse-swelling de-mixing transition (lower critical solution temperature (LCST)-type co-nonsolvency) in aqueous solutions of poly( N-isopropylacrylamide) (PNIPAM) by interacting with the polymer's amide groups. This interaction results in an increase of the total surface area of hydrophobic sites and destabilizes the chains. Here, we make use of this phenomenon to drive the counterintuitive self-assembly of a PNIPAM-containing double-hydrophilic graft copolymer in water-ethanol mixtures at T ≪ LCST. Rheological frequency sweeps are used to quantify the distinct solvation states of PNIPAM at various temperatures and ethanol concentrations. The energy stored through elastic deformation at the de-mixing transition is simply related to the solvent binding. We find that the storage modulus decreases progressively, but nonlinearly with ethanol concentration, which evidences a preferential solvation pattern. Analogously, through a combination of dynamic light scattering and transmission electron microscope analyses, we demonstrate that a low-temperature structure variation takes place by adding ethanol following a similar solvent-content morphology dependent model.

Preparation and Application of Double-Hydrophilic Copolymer as Scale and Corrosion Inhibitor for Industrial Water Recycling

AbstractA novel double-hydrophilic copolymer (acrylic acid-isoprenyl polyethoxy carboxylate, AA-TPEL) is synthesized and the structural properties are identified by FT-IR, 1HNMR and GPC analyses. The inhibitory behavior of the copolymer is determined by using a static scale inhibition method. It is shown that AA-TPEL exhibits an excellent ability to control the formation of CaCO3 scale with an inhibition efficiency of 88.67 % at the 8 mg L–1, and it still maintains a superior efficiency even at increasing solution temperature, pH, and Ca2+ concentration. Weight loss test, potentiodynamic polarization and electrochemical impedance spectroscopy are applied to investigate the inhibition efficiency on mild steel corrosion. All measurements show that, AA-TPEL acts as an efficient corrosion inhibitor and also displays a superior ability to prevent the corrosion of mild steel with approximately 83.21 % inhibition efficiency at the low level of 10 mg L–1. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) are used to characterize the surface morphology of CaCO3 and steel.

Schizophrenic poly(ε-caprolactone)s: synthesis, self-assembly and fluorescent decoration

Double hydrophilic copolymers PCCL-b-PPIL and their pyrene-modified copolymers showed pH-responsive “schizophrenic” aggregation behaviors.

Control over the assembly and rheology of supramolecular networks via multi-responsive double hydrophilic copolymers

An orthogonal control over network formation and dynamics is achieved in metallo-supramolecular micellar gels via multi-responsive double hydrophilic copolymers.

Electrostatic complexation of a double hydrophilic block polyelectrolyte and proteins of different molecular shape

ABSTRACTThe electrostatic complexation between the polyelectrolyte block of the novel double hydrophilic copolymer quaternized poly(3,5‐bis(dimethylaminomethylene) hydroxystyrene)‐b‐poly(ethylene oxide) (QNPHOS‐PEO) and proteins of different molecular shape, that is globular bovine serum albumin (BSA) or rod‐like bovine fibrinogen (FBG), is investigated by means of dynamic, static, and electrophoretic light scattering, as well as analytical ultracentrifugation measurements. The solution behavior, structure, and properties of the formed complexes at pH 7 and 0.01 M ionic strength, as a function of the protein concentration in the solution (or equivalently the charge ratio of the two components), depend on the protein concentration and molecular characteristics. Moreover, the structure of the complexes is greatly influenced by the intrinsic structure of the block polyelectrolyte, which forms rather loose multichain aggregates, due to hydrophobic interactions. A direct correlation between the stability of the preformed complexes against the increase of the solution ionic strength and their structure is established. Finally, the spectroscopic structural investigation of both complexed proteins reveals no signs of protein denaturation upon complexation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1515–1529

Impact of Polyelectrolyte Chemistry on the Thermodynamic Stability of Oppositely Charged Macromolecule/Surfactant Mixtures.

The complexation between hexadecyl- and dodecyltrimethylammonium bromides (CTAB and DTAB) with sodium poly[(vinyl alcohol)-co-(vinyl sulfate)] (PVAS) copolymer of low charge density has been investigated using pyrene fluorescence spectroscopy, electrophoretic mobility, turbidity, and dynamic light scattering measurements. The results indicate that the binding of the cationic surfactant occurs in three steps. At low surfactant concentrations, the cationic amphiphile binds to the vinyl sulfate groups. Above charge neutralization, surfactant binding may occur on the surface of the hydrophobic vinyl sulfate/CnTAB nanoassemblies. At even higher concentrations, the surfactant binds on the nonionic vinyl alcohol units of the polyion which reswells the PVAS/CnTAB complexes and makes them highly soluble in water. In earlier studies on oppositely charged ionic surfactants and homopolyelectrolytes the impact of mixing protocols was found remarkable, especially at surfactant excess, where these systems can be trapped in the charge stabilized colloidal dispersion state. In contrast, in the case of PVAS/CnTAB mixtures the effect of mixing is less pronounced and diminishes with increasing ionic strength or decreasing alkyl chain length of the surfactant. These findings are rationalized by taking into account the different binding mechanism of surfactants on oppositely charged homopolyelectrolytes and double hydrophilic copolymers.

Stealth CD44-targeted hyaluronic acid supramolecular nanoassemblies for doxorubicin delivery: Probing the effect of uncovalent pegylation degree on cellular uptake and blood long circulation

Stealth active targeting nanoparticles (NPs) usually include two types of ligand sites: ligand anchored on distal ends of the polyethylene glycol (PEG) and ligand buried under pegylated layer. The latter typical case is hyaluronic acid (HA)-based NPs; however, there is little information available for the latter NPs about effect of the optimal density of surface PEG coating on the blood circulation time, cellular uptake and in vivo anticancer activity. Thus, in this study, in order to optimize the anticancer effects of HA-based NPs, we focus on how uncovalent pegylation degree modulates blood circulation time and cellular uptake of HA-based NPs. We firstly designed a new double-hydrophilic copolymer by conjugating HP-β-cyclodextrin with HA, and this carrier was further pegylated with adamantyl-peg (ADA-PEG) to form inclusion complex HA-HPCD/ADA-PEG, termed as HCPs. The supramolecular nanoassemblies were fabricated by host–guest and polar interactions between HCPs and doxorubicin (Dox), with vitamin E succinate (VES) being a nanobridge. Despite the active recognition between HA and CD44 receptor, the cellular uptake and targeting efficiency of HA-NPs decreased with the increasing peg density, demonstrating HA was partly buried by high density peg coating. However, the high density of peg coating was beneficial to long circulation time, tumor biodistribution and anticancer activity in vivo. NPs with 5% peg coating had the optimal cellular targeting efficiency in vitro and anticancer effects in vivo. The findings suggest that balancing long circulation property and cellular uptake is important to achieve the optimal antitumor efficacy for pegylated HA-based NPs, and that PEG coating densities cannot be extended beyond a certain density for shielding effect without compromising the efficacy of hyaluronic acid targeted delivery.

Di-Stimuli Responsive Poly(<i>N</i>-Isopropylacrylamide-co-Diethylaminoethylmethacrylate) Copolymer: Synthesis, Characterization and Investigation of Aqueous Dispersion Properties

We report on the synthesis, characterization and aqueous dispersion properties of well-defined double hydrophilic copolymer with pH- and thermo-responsive segments via atom transfer radical polymerization (ATRP). Poly(N-isopropylacrylamide-co-Diethylaminoethylmeth-acrylate), P(NIPAAm-co-DEAEMA), was prepared by ATRP using methyl-4-bromomethyl benzoate initiator. The product was characterized by proton-nuclear magnetic resonance (1H NMR) and attenuated total reflectance infrared (ATR-IR) spectroscopy. The multi-responsive switching between unimer and two types of micellar aggregates were characterized by temperature-dependent dynamic light scattering (DLS). Self-assembles into two types spherical aggregates in 1 mg/mL (0.0315 mM) aqueous solution, depending on solution pH and temperatures were widely investigated. The result shows two types of aggregate with large (280 nm) aggregate and variable sizes of small (17 nm, 25 nm, 45 nm) aggregates depending on temperature ranges from 26 to 40 °C at pH 4.

Di-Stimuli Responsive Poly(<i>N</i>-Isopropylacrylamide-co-Diethylaminoethylmethacrylate) Copolymer: Synthesis, Characterization and Investigation of Aqueous Dispersion Properties

We report on the synthesis, characterization and aqueous dispersion properties of well-defined double hydrophilic copolymer with pH- and thermo-responsive segments via atom transfer radical polymerization (ATRP). Poly(N-isopropylacrylamide-co-Diethylaminoethylmeth-acrylate), P(NIPAAm-co-DEAEMA), was prepared by ATRP using methyl-4-bromomethyl benzoate initiator. The product was characterized by proton-nuclear magnetic resonance (1H NMR) and attenuated total reflectance infrared (ATR-IR) spectroscopy. The multi-responsive switching between unimer and two types of micellar aggregates were characterized by temperature-dependent dynamic light scattering (DLS). Self-assembles into two types spherical aggregates in 1 mg/mL (0.0315 mM) aqueous solution, depending on solution pH and temperatures were widely investigated. The result shows two types of aggregate with large (280 nm) aggregate and variable sizes of small (17 nm, 25 nm, 45 nm) aggregates depending on temperature ranges from 26 to 40 °C at pH 4.

Evaluating the performance of PEG-based scale inhibition and dispersion agent in cooling water systems

In this paper, a new double hydrophilic and environment-friendly polyether copolymer inhibitor, polyethylene glycol double-ester of maleic anhydride—acrylic acid (PEGDMA-AA), was synthesized to inhibit the precipitation of calcium carbonate and Fe(III) scales. Structures of PEG, PEGDMA, and PEGDMA-AA were characterized by Fourier transform infrared spectrometer (FTIR) and 1H Nuclear Magnetic Resonance (1HNMR). The influence of PEGDMA-AA dosage and mass ratio (PEGDMA: AA) toward CaCO3 and Fe scale were tested through static jar scale inhibition and dispersion tests. The optimal mass ratio (PEGDMA: AA) was 1:1 for calcium carbonate inhibition and 1:2 for dispersing Fe(III), respectively. Investigation of influence of solution properties on CaCO3 inhibition was also carried out and dispersion ability for Fe(III) was compared with commercial inhibitors. The effect of PEGDMA-AA on the morphology, size, and crystal form of CaCO3 particles were examined through scanning electron microscopic, transmission electron microscope, X-ray powder diffraction, and FTIR. One supposed mechanism (core–shell structure) was also described in detail.

Micellization of pH-stimulable poly(2-vinylpyridine)-b-poly(ethylene oxide) copolymers and their complexation with anionic surfactants

The micellization behavior was examined for a series of 3 pH-stimulable poly(2-vinylpyridine)-b-poly(ethylene oxide) (P2VP-b-PEO) copolymers, with a constant composition of 67.5±1.5wt% PEO and increasing molecular weight. The micellar characteristics were determined by dynamic, static and electrophoretic light scattering, fluorescence spectroscopy, as well as by 1H NMR in the pH range of 2–7 and in the presence or in the absence of the anionic surfactant sodium dodecylsulfate (SDS). In the absence of SDS, two pH regimes were investigated. For the pH range below 5, the micellar characteristics, such as C.M.C., particle size and zeta potential, were determined. For the first time, it could be shown that the micellization range could be extended to low pH values for relatively high copolymer concentrations. Above pH 5, correlations between the molecular characteristics and the aggregation number as well as the hydrodynamic diameter were established. A fair agreement could be demonstrated with the theoretical predictions for star-like micelles having a P2VP core and a PEO corona. Another original aspect of these double hydrophilic copolymers is their complex formation by electrostatic interaction between the protonated P2VP and SDS. At low pH and low copolymer concentrations, where only protonated unimers are present, the SDS induces the micellization at a given neutralization degree (DN). The process of complex formation was analyzed as a function of DN and pH by DLS, fluorescence spectroscopy, zeta potential measurements and by 1H NMR, this last technique providing information on the mobility of the P2VP/SDS micellar core. A model for the micelle formation mechanism was suggested.

Fabrication and aggregation of thermoresponsive glucose-functionalized double hydrophilic copolymers

Novel double-hydrophilic thermosensitive statistical glycopolymers, poly(N-isopropylacrylamide-co-6-O-vinyladipoyl-d-glucose), were fabricated using a chemoenzymatic process and free radical copolymerization. The structures of the glycopolymers were confirmed by 1H and 13C NMR, and their molar mass distributions determined by gel permeation chromatography. UV–vis spectroscopy data showed that the polymers exhibited reproducible temperature-responsive behavior. The self-assembly and critical aggregation concentration was verified by fluorescence spectroscopy with pyrene acting as a hydrophobic probe. Measurements by laser light scattering and transmission electron microscopy revealed that the glycopolymers were able to self-assemble into aggregates with varying particle sizes and morphologies in aqueous solutions.

PH-Responsive Double-Hydrophilic Block Copolymers: Synthesis and Drug Delivery Application

A novel double-hydrophilic block copolymer P(MEO2MA-co-OEGMA)-b-PAMA has been successfully synthesized by two-step RAFT polymerization. Then, the amino groups of PAMA blocks in the copolymers react with 1-pyrenecarboxaldehyde via a “Schiff-base” reaction, and the resulting copolymers are self-assembled to form spherical micelles in aqueous solution. Because the “Schiff-base” linkage is pH sensitive, the release rate of pyrene depends upon the pH of solution. Complete release is achieved at pH 1, and the control release is much faster at pH 5.5 than that at pH 7.4. With progress of pyrene release, the micelles are disassembled gradually and disappeared completely at last. This double-hydrophilic copolymer is a promising candidate of drug carrier for the aldehyde- containing hydrophobic drugs.