Double Hydrophilic Block Copolymers Research Articles

Amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine block

We present the synthesis and characterization of amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine (PDha) block.

Correction: Amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine block

Correction for ‘Amphiphilic and double hydrophilic block copolymers containing a polydehydroalanine block’ by Mark Billing et al., Polym. Chem., 2017, DOI: 10.1039/c6py02076c.

Core cross-linked double hydrophilic block copolymer micelles based on multiple hydrogen-bonding interactions

Facile preparation and characterization of core cross-linked micelles via strong multiple hydrogen bonds using well-defined thermo-responsive double hydrophilic block copolymers.

Highly stable Au nanoparticles with double hydrophilic block copolymer templates: correlation between structure and stability

We herein report a facile synthetic method for preparing gold nanoparticles (Au NPs) with superior colloidal stability using a series of double hydrophilic block copolymers (DHBC), poly(ethylene oxide)-block-poly(acrylic acid) (PEO-b-PAA), as a template (Au@DHBC NPs).

Dual transitions of toothbrush-like double hydrophilic block copolymers

An interesting thermo-regulated dual transition from unimers to vesicles, and finally to micelles, was reported for the first time based on a toothbrush-like double hydrophilic block copolymer.

Biocompatible Polyion Complex Micelles Synthesized from Arborescent Polymers.

Water-dispersible polyion complex (PIC) micelles were prepared by the self-assembly of an arborescent polystyrene-graft-poly(2-vinylpyridine) copolymer (denoted G0PS-g-P2VP or G1) serving as core and a poly(acrylic acid)-block-poly(2-hydroxyethyl acrylate) (PAA-b-PHEA) double-hydrophilic block copolymer (DHBC) forming a shell. Varying the density of hydrophilic polymer chains in the stabilizing layer provided control over the size and structure of the entities obtained, from large flocculated species to stable isolated PIC micelles with diameters ranging from 42 to 67 nm. The hydrodynamic radius (determined from dynamic light scattering measurements), and the weight-average molar mass (M̅w) and radius of gyration of the scatterers (extracted from static multiangle light scattering data) evidenced the formation of either isolated or aggregated PIC micelles depending on the self-assembly conditions used (pH, concentration and mixing molar ratio f). Changes in the morphology of the arborescent copolymer after complexation were observed by atomic force microscopy (AFM) imaging. In particular, by varying the force applied with the AFM tip on the samples, the core-shell structure of the PIC micelles was clearly evidenced. The PIC micelles displayed no significant cytotoxicity toward mouse fibroblast L929 cells, a standard cell line recommended for toxicity assays, due to the good biocompatibility of the hydrophilic PAA-b-PHEA shell. In spite of a negative residual zeta potential due to an excess of negative charges, fluorescently labeled PIC* micelles were successfully internalized by L929 cells, as confirmed by laser scanning confocal microscopy (LSCM) and transmission electron microscopy (TEM).

Perhydroxycucurbit[6]uril-induced self-assembly of a double-hydrophilic block copolymer in aqueous solution

We reported the preparation of the poly(N-vinyl pyrrolidone)-b-polyethylene glycol (PVP-b-PEG) double-hydrophilic block copolymer by atom transfer radical polymerization (ATRP). The PVP-b-PEG samples were characterized by nuclear magnetic resonance spectroscopy and Fourier translation infrared spectrum. By taking advantage of its exceptional binding affinity, the perhydroxycucurbit[6]uril ((HO)12CB[6]) was used to interact with PVP-b-PEG by hydrogen bond and constructed micelle-like core–shell aggregates with the physical cross-link PVP segments as the core and the extending PEG chains as the outer palisade. The size of aggregates was about 50–300 nm. The particle size of this type of assemblies could be controlled by the weight content of (HO)12CB[6]. The size distribution was broad at high concentrations. The broad size distribution at high (HO)12CB[6] concentration was due to the coexistence of isolated particles and clusters. These novel micelle-like core–shell aggregates could be controlled by pH value. At pH lower than 6 or pH larger than 13, hydrogen bond interactions were destroyed and the formed (HO)12CB[6]-induced PVP-b-PEG assemblies could be destructed.

Protein encapsulation and release from PEO-b-polyphosphoester templated calcium carbonate particles

Calcium carbonate particles are promising candidates as proteins carriers for their controlled delivery in the body. The present paper aims at investigating the protein encapsulation by in situ precipitation of calcium carbonate particles prepared by a process based on supercritical CO2 and using a new type of degradable well-defined double hydrophilic block copolymers composed of poly(ethylene oxide) and polyphosphoester blocks acting as templating agent for the calcium carbonate. For this study, lysozyme was chosen as a model for therapeutic protein for its availability and ease of detection. It was found that by this green process, loading into the CaCO3 microparticles with a diameter about 2μm can be obtained as determined by scanning electron microscopy. A protein loading up to 6.5% active lysozyme was measured by a specific bioassay (Micrococcus lysodeikticus). By encapsulating fluorescent-labelled lysozyme (lysozyme-FITC), the confocal microscopy images confirmed its encapsulation and suggested a core–shell distribution of lysozyme into CaCO3, leading to a release profile reaching a steady state at 59% of release after 90min.

Formation of mesopores inside platinum nanospheres by using double hydrophilic block copolymers

We report a simple and facile method for the formation of mesopores inside Pt nanospheres using double hydrophilic block copolymer poly(ethylene oxide-b-vinylpyridine) as template and structure directing agent. The dissolved Pt species strongly interact with the vinylpyridine and ethylene oxide units. The reduction of the Pt species in the presence of polymeric micelles leads to the formation of uniform mesoporous Pt nanospheres. [Display omitted]

Salt‐ and pH‐Responsive Semirigid/Flexible Double‐Hydrophilic Block Copolymers

Double‐hydrophilic block copolymers (DHBCs) of poly((4‐diethylamino)‐(E)‐stilbene)‐alt‐maleic acid)‐block‐acryloyl morpholine (DEASti‐alt‐MA)‐b‐ACMO), semirigid‐b‐flexible coil structures, form polyion complexes (PICs) in aqueous solutions. The pH and salt responsiveness of the PICs are studied using dynamic light scattering (DLS). PIC complex formation is dependent on block segment lengths and pH. The particle size increases as the pH approaches the IEP (isoelectric point) of the DHBC. The salt responsiveness is also measured by using DLS to monitor PIC size for four examples with different segment molar masses. These PICs exhibit an antipolyelectrolyte effect with increasing hydrodynamic diameter as ionic strength (NaCl) increases from 0.01 to 2.0 m. PICs are more stable at higher ionic strengths with higher ACMO molar mass. image

Assembly of Double-Hydrophilic Block Copolymers Triggered by Gadolinium Ions: New Colloidal MRI Contrast Agents.

Mixing double-hydrophilic block copolymers containing a poly(acrylic acid) block with gadolinium ions in water leads to the spontaneous formation of polymeric nanoparticles. With an average diameter near 20 nm, the nanoparticles are exceptionally stable, even after dilution and over a large range of pH and ionic strength. High magnetic relaxivities were measured in vitro for these biocompatible colloids, and in vivo magnetic resonance imaging on rats demonstrates the potential utility of such polymeric assemblies.

Tuning of Polymeric Nanoparticles by Coassembly of Thermoresponsive Polymers and a Double Hydrophilic Thermoresponsive Block Copolymer

The coassembly behavior of thermoresponsive statistical copolymers and a double hydrophilic block copolymer having a permanently hydrophilic block and a thermoresponsive block is investigated. By adjusting the hydrophilicity of the thermoresponsive statistical copolymers, hybrid nanoparticles are obtained with various ratios of the two species. Importantly, the size of these nanoparticles can be controlled in between 40 and 250 nm dependent on the TCP and the amount of statistical copolymers in the solution. Simultaneous analysis of static and dynamic light scattering data indicates that the possible structure of nanoparticles varies from hard sphere to less compact architecture and most probably depends on a difference between cloud point temperatures of individual components. This developed coassembly method provides a simple platform for the preparation of defined polymeric nanoparticles.

Carboxylate-Terminated Double-Hydrophilic Block Copolymer as an Effective Inhibitor for Carbonate and Sulphate Scales

Abstract For the control of carbonate and sulphate scales, a new type of green scale inhibitors AQn was synthesized. The thermal stability and the molecular weight of the copolymers were investigated by thermal gravimetric analysis and gel permeation chromatography, respectively. The anti-scale property of the AQn copolymers towards CaCO3 and CaSO4 in the artificial cooling water was studied through static scale inhibition tests. The results show that both CaCO3 and CaSO4 inhibition increase with increasing the degree of polymerization of AQn from 5 to 15. The dosage of AQn plays also an important role on CaCO3 and CaSO4 inhibition. Surface morphology characterization of CaCO3 and CaSO4 was investigated with combination of scanning electronic microscopy (SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analysis. An inhibition mechanism is proposed that the interactions between calcium and polyethylene glycol (PEG) are the fundamental impetus to restrain the formation of the scale in cooling water systems.

Reversible Vesicle–Spherical Micelle Transition in a Polyion Complex Micellar System Induced by Changing the Mixing Ratio of Copolymer Components

The mixing ratio dependence of the morphology of a polyion complex micelle formed of an anionic–neutral double-hydrophilic block copolymer (AP) and a cationic–neutral double-hydrophilic block copolymer (MP) in 0.1 M aqueous NaCl solution was investigated by using small-angle X-ray scattering (SAXS), electrophoretic light scattering (ELS), and isothermal titration calorimetry (ITC), under the condition that the anionic and cationic block chains are much longer than the neutral block chains. When the anionic and cationic monomer units in the solution are nearly equimolar, the net charge of the polyion complex micelle is close to zero, and the bilayer vesicle is formed. However, when the anionic or cationic monomer units in the solution are richer than the other, the polyion complex micelle is charged by including the excess block copolymer component to form the smaller spherical micelle. The morphology transition between the vesicle and spherical micelle can take place reversibly by simply adding AP or MP i...

Temperature and anion responsive self-assembly of ionic liquid block copolymers coating gold nanoparticles

In this paper, double hydrophilic ionic liquid block copolymers (ILBCs), poly poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)]-block-(N-isopropylacrylamide) (PMMPImB-b-PNIPAAm) was first synthesized by reversible additionfragmentation chain transfer (RAFT) and then attached on the surface of gold nanoparticles (Au NPs) via a strong gold-sulfur bonding for preparing hybrid nanoparticles (PMMPImB-b-PNIPAAm-@-Au NPs). The hybrid NPs had a three layers micelle-like structure, including a gold core, thermo-responsive inner shell and anion responsive outer corona. The self-assembling behavior of thermal- and anion-response from shell and corona were respectively investigated by change of temperature and addition of (CF3SO2)2N−. The results showed the hybrid NPs retained a stable dispersion beyond the lower critical solution temperature (LCST) because of the space or electrostatic protecting by outer PMMPImB. However, with increasing concentration of (CF3SO2)2N−, the micellization of self-assembling PMMPImB-b-PNIPAAm-@-Au NPs was induced to form micellar structure containing the core with hydrophobic PMMPImB-(CF3SO2)2N− surrounded by composite shell of Au NPs-PNIPAAm via the anionresponsive properties of ILBCs. These results indicated that the block copolymers protected plasmonic nanoparticles remain self-assembling properties of block copolymers when phase transition from outer corona polymer.

Folding Behaviors of Protein (Lysozyme) Confined in Polyelectrolyte Complex Micelle.

The folding/unfolding behavior of proteins (enzymes) in confined space is important for their properties and functions, but such a behavior remains largely unexplored. In this article, we reported our finding that lysozyme and a double hydrophilic block copolymer, methoxypoly(ethylene glycol)5K-block-poly(l-aspartic acid sodium salt)10 (mPEG(5K)-b-PLD10), can form a polyelectrolyte complex micelle with a particle size of ∼30 nm, as verified by dynamic light scattering and transmission electron microscopy. The unfolding and refolding behaviors of lysozyme molecules in the presence of the copolymer were studied by microcalorimetry and circular dichroism spectroscopy. Upon complex formation with mPEG(5K)-b-PLD10, lysozyme changed from its initial native state to a new partially unfolded state. Compared with its native state, this copolymer-complexed new folding state of lysozyme has different secondary and tertiary structures, a decreased thermostability, and significantly altered unfolding/refolding behaviors. It was found that the native lysozyme exhibited reversible unfolding and refolding upon heating and subsequent cooling, while lysozyme in the new folding state (complexed with the oppositely charged PLD segments of the polymer) could unfold upon heating but could not refold upon subsequent cooling. By employing the heating-cooling-reheating procedure, the prevention of complex formation between lysozyme and polymer due to the salt screening effect was observed, and the resulting uncomplexed lysozyme regained its proper unfolding and refolding abilities upon heating and subsequent cooling. Besides, we also pointed out the important role the length of the PLD segment played during the formation of micelles and the monodispersity of the formed micelles. Furthermore, the lysozyme-mPEG(5K)-b-PLD10 mixtures prepared in this work were all transparent, without the formation of large aggregates or precipitates in solution as frequently observed in other protein-polyelectrolyte systems. Hence, the present protein-PEGylated poly(amino acid) mixture provides an ideal water-soluble model system to study the important role of electrostatic interaction in the complexation between proteins and polymers, leading to important new knowledge on the protein-polymer interactions. Moreover, the polyelectrolyte complex micelle formed between protein and PEGylated polymer may provide a good drug delivery vehicle for therapeutic proteins.

Fluorescence ON–OFF switching using micelle of stimuli-responsive double hydrophilic block copolymers: Nile Red fluorescence in micelles of poly(acrylic acid-b-N-isopropylacrylamide)

The dual-mode fluorescence ON–OFF switching of Nile Red (NR) by using stimuli-responsive polymeric micelle of poly(acrylic acid-b-N-isopropylacrylamide) (PAA-b-PNIPAM) has been studied. PAA-b-PNIPAM, one of double hydrophilic block copolymers, is known to form PNIPAM-core/PAA-corona micelles in aqueous solutions when the temperature of the solution is elevated up to the lower critical solution temperature (LCST) of PNIPAM block. It also forms PAA-core/PNIPAM-corona micelles when the anionic PAA block is charge-neutralized with cationic cetyltrimethylammonium ion. Fluorescence properties of NR in the micelles are elucidated by observing various fluorescence parameters such as intensity, polarization, and quantum yield. It is found that the fluorescence intensity is negligibly low (OFF-state) when PAA-b-PNIPAM exists as a form of unimer, whereas it is remarkably enhanced (ON-state) when the PNIPAM-core or PAA-core micelles are formed. These results demonstrate that a novel fluorescence ON–OFF switching system can be constructed by using PAA-b-PNIPAM micelles and NR.

Double-hydrophilic block copolymer micelles for drag delivery of poorly soluble vitamins in living organisms

Double-hydrophilic block copolymer micelles for drag delivery of poorly soluble vitamins in living organisms

PLGA-lecithin-PEG-folate core–shell nanoparticles for cisplatin-prodrug targeted delivery

possibilities using macrocyclic host molecules for drug delivery. In one system, for example, anticancer drug doxorubicin functionalized αcyclodextrins (α-CDs) could form complex with double-hydrophilic block copolymers poly(ethylene glycol)-b-poly(2-methacryloyloxyethyl phosphorylcholine) (PEG-bPMPC) block copolymers, leading to formation of pH responsive pseudopolyrotaxane prodrug micelles (Scheme 1, A). It should be noted that this facile strategy could increase the drug content in the micelles due to the fact that α-CD could thread onto PEG chains in a well ordered and high-density manner. Besides, we also developed a facile way to achieve accumulation of nanocarriers in the tumor site by using dual pH responsive pillar[5]arene based supramolecular prodrugmicelles (Scheme 1,B). Results showed that the as-prepared prodrug micelles could be aggregated upon acidic condition, which led to enhanced accumulation and better therapy effect.

Double-Hydrophilic Block Copolymer as an Environmentally Friendly Inhibitor for Calcium Sulfate Dehydrate (Gypsum) Scale in Cooling Water Systems

Abstract In this study, a novel environmentally friendly copolymer acrylic acid-itaconic acid-allylpolyethoxy maleic carboxylate was synthesized and used for inhibiting the calcium sulfate dehydrate (gypsum) scale. The properties of the synthesized copolymer were characterized by Fourier-transform infrared, nuclear magnetic resonance spectroscopy and thermal gravity analysis. Also, the structure and morphology changes of scale crystals were studied by scanning electronic microscopy, transmission electron microscopy and X-ray powder diffraction analysis. The copolymer inhibition ability was evaluated by means of static scale inhibition experiments. Results show that the copolymer was effective in inhibiting the scales by changing the size and morphology of the crystals. The maximum inhibition efficiency was 99.8% at a concentration of 2 mg · L– 1, far more efficient than most commercial inhibitors.