Poly(ethylene Glycol)-block-polystyrene Research Articles

Effects of Processing pH on Emission Intensity of Over-1000 nm Near-Infrared Fluorescence of Dye-Loaded Polymer Micelle with Polystyrene Core.

Fluorescence imaging using the over-thousand-nanometer (OTN) near-infrared (NIR) light is an emerging method for an in vivo imaging analysis of deep tissues without physical sectioning. Polymer micelle nanoparticles (PNPs) composed of organic polymers encapsulating an OTN-NIR fluorescent dye, IR-1061, in their hydrophobic core are expected to be biocompatible probes. Because IR-1061 quickly quenches due to the vibration of polar hydroxyl bonding in its surroundings, the influence of hydroxyl ions should be minimized. Herein, we investigated the effect of the hydrogen ion concentration during the preparation process using IR-1061 and an organic polymer, poly(ethylene glycol)-block-polystyrene (PEG-b-PSt), on the emission properties of the obtained OTN-PNPs. The OTN-PNP has a hydrodynamic diameter of 20 - 30 nm and emits 1110-nm fluorescence that is applicable to angiography. The loading efficiency of IR-1061 in the OTN-PNPs increased when prepared in an aqueous solution with a low hydroxyl ion concentration. In this solution (pH 3.0), highly emissive OTN-PNPs was obtained with IR-1061 at lower nominal concentrations. Decreasing the hydroxyl ion concentration during the preparation process yields highly emissive OTN-PNPs, which may improve the in vivo imaging analysis of biological phenomena in deep tissues.

Polymer-coated gold nanoparticles and polymeric nanoparticles as nanocarrier of the BP100 antimicrobial peptide through a lung surfactant model

Pneumonia is caused by microorganisms that settle in the lungs, which may reach the pulmonary alveoli and cause respiratory failure. Antibiotic treatments are the most used, although their use may not be efficient due to bacterial resistance. The antimicrobial peptide BP100 is a promising candidate for a new antibiotic due to its low susceptibility to bacterial resistance. It can be most effective when carried with gold nanoparticles (AuNPs) and polymer coatings for topical use. The goal of this work is to evaluate the effect of the transposition of the BP100 peptide carried on a gold nanoparticle coated with three types of polymers (polyethylene glycol (PEG), polystyrene (PS) and polyethylene glycol-block-polystyrene (PEG-b-PS)) using a lung surfactant (LS) model. The Gibbs free energies for nanoparticle transpositions are performed using coarse-grained molecular dynamics (CGMD) and umbrella sampling. The results demonstrate that the process is spontaneous for the BP100 adsorbed on the AuNPs encapsulated with PEG. The PEG effect on the AuNP-BP100-PEG system works as a protection method or a ligand competition for BP100 transposition. However, it is observed that the BP100-PEG nanoparticle breaks up as reaching the aqueous phase. Then, BP100 migrates to the polar heads region of the negatively charged phospholipids. It is possible to evaluate the effects of nanocarriers on the LS model. Besides that it is suggested the feasibility of applying antimicrobial peptides carried on PEG capped AuNPs for possible treatments of lung diseases.

Magnetic stomatocyte-like nanomotor as photosensitizer carrier for photodynamic therapy based cancer treatment

Amphiphilic block copolymer can self-assemble to stomatocyte-like structure as drug delivery carrier. Photodynamic therapy (PDT) is an emerging modality for cancer treatment. However, PDT has various problems, such as weak tumor accumulation ability of photosensitizers (PSs), short lifetime of singlet oxygen (1O2, main reactive oxygen species in PDT) and tumor hypoxia microenvironment, to restrict its therapeutic efficacy. To convey PSs to tumor tissues and improve PDT efficacy, iron oxide nanoparticles (IONPs) were loaded inside the self-assembly stomatocytes-like structure of poly(ethylene glycol) block polystyrene (PEG-b-PS) as nanomotors (IONPs loaded stomatocytes nanomotors, denoted IS-NMs) for PS (zinc phthalocyanine, ZnPc) delivery. The hybrid nanomotors (iron oxide nanoparticles loaded stomatocytes@ZnPc nanomotors, denoted ISP-NMs) can be gathered in tumor tissues under magnetic field owing to magnetism of IONPs. After been trapped by cancer cells, IONPs can catalyze decomposition of endogenous H2O2 to generate O2 as propelling force for ISP-NMs movement. The motion characteristics of ISP-NMs expanded the distribution of ZnPc to enlarge ROS reactive distribution and enhance the activity of PDT. And the generated O2 can be supplied for PDT process to ensure its high-performance. Furthermore, ISP-NMs have nuclear magnetic resonance imaging (MRI) function since IONPs are efficient T2 contrast agent.

Self-assembly synthesis of solid polymer electrolyte with carbonate terminated poly(ethylene glycol) matrix and its application for solid state lithium battery

Abstract A facile one-pot synthesis of solid polymer electrolytes (SPEs), composed of carbonate terminated poly(ethylene glycol) (CH3O-PEG-IC), poly(ethylene glycol)-block-polystyrene (PEG-b-PS) block copolymer nanoparticles containing a conductive PEG corona, fumed SiO2 and LiTFSI salt via polymerization-induced self-assembly is proposed. This method to prepare SPEs has the advantages of one-pot convenient synthesis, avoiding use of organic solvent and conveniently adding inorganic additives. CH3O-PEG-IC combines advantages of PEG and polycarbonate, the in situ synthesized PEG-b-PS nanoparticles containing a rigid polystyrene (PS) core and a PEG corona guarantee continuous lithium ion transport in the synthesized SPEs, and the fumed SiO2 optimizes the interfacial properties and improves the electrochemical stability, all of which afford SPEs a well considerable room temperature ionic conductivity of 1.73 × 10−4 S/cm, high lithium transference number of 0.53, and wide electrochemical stability window of 5.5 V (vs. Li+/Li). By employing these SPEs, the assembled solid state cells of LiFePO4|SPEs|Li exhibit considerable cell performance.

Synthesis of diblock copolymer nano-assemblies: Comparison between PISA and micellization

RAFT dispersion polymerization following the formulation of polymerization induced self-assembly (PISA) and micellization of pre-prepared amphiphilic block copolymers in block-selective solvents are generally used to prepare block copolymer nano-assemblies. Herein, we make a comparison between these two methods by employing two typical block copolymers of poly(acrylic acid)-block-polystyrene (PAA-b-PS) and poly(ethylene glycol)-block-polystyrene (PEG-b-PS). It is found that the block copolymer nano-assemblies prepared by these two methods are similar with each other when the solvophilic block is relatively long and the solvophobic block is relatively short. Otherwise, the block copolymer nano-assemblies by these two methods are different. The possible reasons leading to the difference between PISA and micellization are discussed, and the kinetic factors including temperature, polymer concentration and solvent are ascribed. It is thought that the present study is helpful to clarify how the kinetic factors beyond the block copolymer itself affecting block copolymer morphology.

Methods for production of uniform small-sized polymersome with rigid membrane

We report a facile methodology for the formation of uniform small-sized poly(ethylene glycol)-block-polystyrene (PEG-b-PS) polymersomes, via extrusion and sonication methods by using organic solvent as plasticizing agent.

Polymerization‐induced self‐assembly of block copolymer through dispersion RAFT polymerization in ionic liquid

ABSTRACTPolymerization‐induced self‐assembly of block copolymer through dispersion RAFT polymerization has been demonstrated to be a valid method to prepare block copolymer nano‐objects. However, volatile solvents are generally involved in this preparation. Herein, the in situ synthesis of block copolymer nano‐objects of poly(ethylene glycol)‐block‐polystyrene (PEG‐b‐PS) in the ionic liquid of 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([BMIN][PF6]) through the macro‐RAFT agent mediated dispersion polymerization is investigated. It is found that the dispersion RAFT polymerization of styrene in the ionic liquid of [BMIN][PF6] runs faster than that in the alcoholic solvent, and the dispersion RAFT polymerization in the ionic liquid affords good control over the molecular weight and the molecular weight distribution of the PEG‐b‐PS diblock copolymer. The morphology of the in situ synthesized PEG‐b‐PS diblock copolymer nano‐objects, e.g., nanospheres and vesicles, in the ionic liquid is dependent on the polymerization degree of the solvophobic block and the concentration of the fed monomer, which is somewhat similar to those in alcoholic solvent. It is anticipated that the dispersion RAFT polymerization in ionic liquid broads a new way to prepare block copolymer nano‐objects. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1517–1525

Ionic liquid-mediated synthesis and self-assembly of poly(ethylene glycol)-block-polystyrene copolymer by ATRP method

Poly(ethylene glycol)-block-polystyrene (PEG-b-PS) was synthesized by the atom transfer radical polymerization of styrene using PEG-Br as the macroinitiator in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]). CuBr and 2,2″-bipyridyl were used as the catalyst and ligand, respectively. The structure, composition, and molecular weight of the PEG-b-PS copolymer were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and gel permeation chromatography. The PEG-b-PS copolymer with a high molecular weight (Mn = 51,000 g mol−1) and relatively low polydispersity index (PDI = 1.35) was formed at 110 °C for 5 h. Self-assembly of this amphiphilic block copolymer in toluene at different concentrations and in dimethylformamide (DMF)/water systems was also examined. Transmission electron microscopy showed that the block copolymer formed different morphologies spontaneously according to the different solvent systems used.

Effects of various polymer brushes on the crystallization of poly(ethylene glycol) in poly(ethylene glycol)-b-polystyrene and poly(ethylene glycol)-b-poly(methyl methacrylate) single crystals

The effects of PS and PMMA brushes on the crystallization of PEG in poly(ethylene glycol)-block-polystyrene (PEG-b-PS) and poly(ethylene glycol)-block-poly(methyl methacrylate) (PEG-b-PMMA) single crystals that have the same crystalline block molecular weight but different amorphous block molecular weights were investigated. The quality of the solvent (amyl acetate) employed and the interaction of the single-crystal substrate with the brush were found to influence the conformations of the PS and PMMA brushes, leading to more extended and packed pancake conformations, respectively. For PS and PMMA brushes with similar features, the conformation of the PMMA brushes led to a higher osmotic pressure on the substrate, so the substrate thickness was found to be significantly less than that seen when PS brushes were used. Even when the molecular weight of PMMA (M n = 8,700 g/mol) is considerably lower than that of PS (M n = 14,800 g/mol), the substrate in the presence of PMMA is thinner than that in the presence of PS (3.65 vs. 4.14 nm). Moreover, because there is less entropic repulsion between PS brushes than between PMMA brushes, the thickening of the substrate chains beneath them was more conspicuous when the crystallization temperature was increased.

Nascent lateral habits of solution crystallization of poly(ethylene glycol)-block-polystyrene diblock copolymers

Some special habits of dilute solution-grown single crystals were introduced by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM) equipped with electron diffraction (ED). Well-defined block copolymers of poly(ethylene glycol)-block-polystyrene (PEG-b-PS) having predetermined molecular weight and narrow molecular weight distribution (1.06–1.08) were synthesized by atom transfer radical polymerization (ATRP). The single crystals of PEG-b-PS copolymers were grown in a mixed solvent comprised of chlorobenzene/octane and separately in amyl acetate, both using a self-seeding technique. We were capable to develop various growth fronts that resulted from different growth rates through infinitesimal temperature fluctuations. Elevated crystallization temperatures and a higher ratio of molecular weight of PS to that of PEG intensified the curvatures. The corresponding overall, crystalline, and amorphous thickness of a given single crystal, either in square and truncated shapes or with concave and convex lateral sides, had high consistency with each other.