Star-shaped Copolymers Research Articles

HPMA-based star polymer biomaterials with tuneable structure and biodegradability tailored for advanced drug delivery to solid tumours

Design, controlled synthesis, physico-chemical and biological characteristics of novel well-defined biodegradable star-shaped copolymers intended for advanced drug delivery is described. These new biocompatible star copolymers were synthesised by grafting monodispersed semitelechelic linear (sL) N-(2-hydroxypropyl)methacrylamide copolymers onto a 2,2-bis(hydroxymethyl)propionic acid (bisMPA)-based polyester dendritic core of various structures. The hydrodynamic diameter of the star copolymer biomaterials can be tuned from 13 to 31 nm and could be adjusted to a given purpose by proper selection of the bisMPA dendritic core type and generation and by considering the sL copolymer molecular weight and polymer-to-core molar ratio. The hydrolytic degradation was proved for both the star copolymers containing either dendron or dendrimer core, showing the spontaneous hydrolysis in duration of few weeks. Finally, it was shown that the therapy with the biodegradable star conjugate with attached doxorubicin strongly suppresses the tumour growth in mice and is fully curative in most of the treated animals at dose corresponding approximately to one fourth of maximum tolerated dose (MTD) value. Both new biodegradable systems show superior efficacy and tumour accumulation over the first generation of star copolymers containing non-degradable PAMAM core.

High-Throughput Preparation of Antibacterial Polymers from Natural Product Derivatives via the Hantzsch Reaction.

SummaryThe Hantzsch and free-radical polymerization reactions were combined in a one-pot high-throughput (HTP) system to simultaneously prepare 30 unique polymers in parallel. Six aldehydes derived from natural products were used as the starting materials to rapidly prepare the library of 30 poly(1,4-dihydropyridines). From this library, HTP evaluation methods led to the identification of an antibacterial polymer. Mechanistic studies revealed that the dihydropyridine group in the polymer side-chain structure plays an important role in resisting bacterial attachment to the polymer surface, thus leading to the antibacterial function of this polymer. This research demonstrates the value of multicomponent reactions (MCRs) in interdisciplinary fields by discovering functional polymers for possible practical applications. It also provides insights to further developing new functional polymers using MCRs and HTP methods with important implications in organic chemistry, polymer chemistry, and materials science.

Thermally stable core-shell star-shaped block copolymers for antifouling enhancement of water purification membranes

Star-shaped block copolymers (SPs), consisting of a hydrophobic core and hydrophilic arms, are a new material architecture introduced to the area of antifouling coatings for water filtration membranes. The unique self-assembly behavior of these SPs on hydrophobic membranes surface allows the formation of an ultrathin coating (less than 15 nm), rendering a highly hydrophilic antifouling membrane surface. Here, we have judiciously examined several important structural and process parameters, such as the chemical composition of SPs and surface properties (e.g., surface potential, coverage, and wettability) driven by a mono- or bi-layered assembly of SPs, to acquire a highly hydrophilic and thermally stable antifouling coating on a hydrophobic ultrafiltration (polysulfone, PSF) membrane for oil sands produced water treatment. Among three types of SPs (e.g., SP1 with 100% amine, SP2 with 55% amine/45% PEG, and SP3 with 35% carboxylic acid/65% PEG moieties in the arms) and their variable coating conditions, the bilayer coating comprised of SP3 top-layer and SP1 bottom-layer exhibited the best hydrophilicity and anti-oil fouling efficiency showing 2–4 times higher water flux compared to an unmodified PSF membrane during the filtration of synthetic oil-water emulsions conducted in both constant flux mode and constant pressure mode. Outstanding antifouling efficiency of the bilayer coating toward natural organic matters (NOMs) was also verified by using bovine serum albumin (BSA) and humic acid (HA) as the model foulants. The bilayer-coated membrane retained more than 80% and 90% (for nano and micron size oil emulsion, respectively) of its initial antifouling efficiency even after rigorous thermal treatment for an extended period (80 °C for 1 week), which demonstrates its feasibility for high-temperature membrane operation.

Synthesis of a branched star copolymer by aqueous SET-LRP and its thermo-stimuli response

Thermally responsive star-shaped polyacrylamides have been efficiently synthesized by copolymerization of acrylamide (AM) with AM-based macromonomer (MPAD) by single-electron-transfer living radical polymerization. Copolymerizations using Gly-Br3 as an initiator were catalyzed by full in situ disproportionation of CuBr/Me6TREN to Cu(0) powder and CuBr2 and were performed in H2O at 25 °C. The polymerization proceeded smoothly, and the time dependence of ln([M]0/[M]) was linear, implying that the copolymerization was a living polymerization. The polymer products were characterized by FTIR spectroscopy, 1H NMR spectrometry, and atomic force microscopy. The responsiveness of the water-soluble star-shaped copolymers were studied by turbidity measurements, dynamic light scattering, and transmission electron microscopy. The lower critical solution temperature of a random copolymer can be tuned by changing the feed ratio of MPAD in its synthesis. The phase transition temperature of the copolymer decreased with increasing MPAD content. At a feed ratio of MPAD of 10%, the copolymer obtained exhibited a strong thermal response and could form vesicles.

Antisense LNA-loaded nanoparticles of star-shaped glucose-core PCL-PEG copolymer for enhanced inhibition of oncomiR-214 and nucleolin-mediated therapy of cisplatin-resistant ovarian cancer cells.

We aimed to inhibit overexpressed oncomiR-214 in cisplatin (CIS)-resistant ovarian cancer (OC) and perform targeted therapy of sensitized cells using a novel polymeric drug delivery system (DDS). A system of nanoparticles (NPs) of star-shaped glucose-core polycaprolactone-polyethylene glycol (Glu-PCL-PEG) block copolymer containing cisplatin (CIS-PCL NPs) and locked nucleic acid (LNA) anti-miR-214 (LNA-PCL NPs) were prepared and anti-nucleolin aptamer was conjugated to the surface of prepared NPs to prepare Ap-CIS-PCL NPs and Ap-LNA-PCL NPs, respectively. The cancer-targeting ability of the NPs was confirmed and the CIS-resistant A2780 (A2780 R) cells were transfected with Ap-LNA-PCL NPs to inhibit oncomiR-214 and sensitize the cells to CIS. Next, the miR-214-inhibited cells were exposed to the Ap-CIS-NPs and the deracination efficiency of targeted DDS was evaluated. The oncomiR-214 in A2780 R cells were harnessed by Ap-LNA-PCL NPs, and nucleolin-mediated endocytosis of targeted polymeric DDSs containing CIS into miR-214-inhibited A2780 R cells caused enhanced apoptosis, which was further confirmed by apoptosis detection and evaluation of downstream genes expression. Targeted inhibition of miR-214 using the developed NPs containing LNA can decrease drug-resistant properties of cancer cells and may enhance the efficiency of targeted DDSs.

Tetraphenylsilane-Cored Star-Shaped Polymer Micelles with pH/Redox Dual Response and Active Targeting Function for Drug-Controlled Release.

This paper presents the design and synthesis of star-shaped copolymers with two poly[2-(diethylamino)ethyl methacrylate] and poly(ethylene glycol) blocks linked via a disulfide bond and each end of the four arms capped by folic acid (FA), from which the prepared nanodrug carriers simultaneously possess pH/redox dual response and active targeting functions. The polymer micelles exhibit excellent stability as reflected by their low critical micelle concentration values of 1.03-2.51 mg/L. The doxorubicin (DOX)-loaded polymer micelles are in the range of 108 to 143 nm, and the DOX-loading capacities are found to be up to 32.3%. The sensitive pH and redox responses are demonstrated by examining the drug release behaviors under the varied acidic condition from pH 7.4 to 5.0 and the glutathione concentrations from 0 to 10 mM, respectively. Moreover, the observation of confocal laser scanning microscopy confirms that the functionalization of arm ends by FA indeed enhances the internalization of DOX-loaded micelle particles in HeLa cells. As a result, the DOX-loaded nanocarriers can deliver therapeutic drugs to target HeLa cells, and the viability of HeLa cells (10.1%) approaches the value of the pristine DOX (9.98%), showing promising application as drug delivery nanocarriers for safe and highly efficient cancer therapy.

Synthesis of UHMW Star-Shaped AB Block Copolymers and Their Flocculation Efficiency in High-Ionic-Strength Environments

The negative effect of multivalent cations such as Ca2+ and Mg2+ on the flocculation efficiency of anionic polymeric flocculants has proven to be a difficult challenge to overcome in recent years. ...

Polydopamine-Based "Four-in-One" Versatile Nanoplatforms for Targeted Dual Chemo and Photothermal Synergistic Cancer Therapy.

The development of versatile nanoscale drug delivery systems that integrate with multiple therapeutic agents or methods and improve the efficacy of cancer therapy is urgently required. To satisfy this demand, polydopamine (PDA)-modified polymeric nanoplatforms were constructed for the dual loading of chemotherapeutic drugs. The hydrophobic anticancer drug docetaxel (DTX) was loaded into the polymeric nanoparticles (NPs) which were fabricated from the star-shaped copolymer CA-PLGA. Then DTX-loaded NPs were coated with PDA, followed by conjugation of polyelethyl glycol (PEG)-modified targeting ligand aptamer AS1411(Apt) and adsorption of the hydrophilic anticancer drug doxorubicin (DOX). This “four-in-one” nanoplatform, referred to as DTX/NPs@PDA/DOX-PEG-Apt, demonstrated high near-infrared photothermal conversion efficiency and exhibited pH and thermo-responsive drug release behavior. Furthermore, it was able to specifically target MCF-7 human breast carcinoma cells and provide synergistic chemo-photothermal therapy to further improve the anticancer effect both in vitro and in vivo, providing a novel promising strategy for cancer therapy.

Indometacin-loaded micelles based on star-shaped PLLA-TPGS copolymers: effect of arm numbers on drug delivery

Star-shaped copolymers based on star-shaped poly (L-lactide) (s-PLLA) and tocopheryl polyethylene glycol 1000 succinate (TPGS) (s-PLLA-TPGS) were synthesized with structural variation on arm numbers in order to investigate the relationship between the arm numbers of s-PLLA-TPGS copolymers and their micelle properties. The structure and Mw of s-PLLA-TPGS were characterized with 1H NMR, GPC, DSC, and XRD. The indometacin(IMC)-loaded s-PLLA-TPGS micelles were obtained by dialysis method. The effects of arm numbers of s-PLLA-TPGS copolymers on surface morphology, particle size, zeta potential, drug loading content (LC), drug encapsulation efficiency (EE), and in vitro drug release behavior of prepared micelles were studied. The results indicated that the average diameters, LC, and EE of IMC-loaded s-PLLA-TPGS micelles gradually increased in the order of 4-arm, 5-arm, and 6-arm s-PLLA-TPGS copolymers. The in vitro release studies showed that the IMC accumulative release can be decreased by increasing the arm numbers of the s-PLLA-TPGS copolymers, and the release profiles of IMC from the s-PLLA-TPGS copolymers followed the Baker-Lonsdale model equation. The results suggest that the arm number regulation of s-PLLA-TPGS copolymers can provide a new strategy for designing drug carriers of high efficiency.

Cyclodextrin based unimolecular micelles with targeting and biocleavable abilities as chemotherapeutic carrier to overcome drug resistance.

An amphiphilic star-shaped copolymer β-CD-g-PCL-SS-PEG-FA, consisting of a β-cyclodextrin (β-CD) core as well as grafted with bioreducible disulfide linkage in PCL-SS-PEG multiarms and targeting folic acid (FA) as end moiety, is designed with unimolecular micelles formation ability for targeted transport of chemotherapeutics to drug resistant tumor cells. Firstly, β-CD was utilized as core to growth PCL arms by ring-opening polymerization (ROP) of ε-CL, before disulfide terminal group transformation to render β-CD-g-PCL-SS-COOH. Secondly, α-hydroxy-ω-amine protected PEG (HO-PEG-NHBoc) was connected to β-CD-g-PCL-SS-COOH to obtain amphiphilic β-CD-g-PCL-SS-PEG, where PCL and PEG were connected via bioreducible disulfide bond. After deprotection of -Boc group, FA was introduced onto the distal end of block arms to obtain the desired β-CD-g-PCL-SS-PEG-FA copolymer. Because of highly branched core-shell amphiphilic structures, β-CD-g-PCL-SS-PEG-FA could act as unimolecular micelles. Interestingly, this unimolecular micelle could release the encapsulated drug in a glutathione (GSH) dependent manner due to disulfide linkage. More importantly, this unimolecular micelle could load doxorubicin (DOX) to promote its cellular uptake in multidrug resistance (MDR) protein overexpression tumor cells, by taking the advantage of FA targeting group and intracellular high GSH level in cancer cells. Together with satisfactory biocompatibility, this novel star-like β-CD-g-PCL-SS-PEG-FA unimolecular micelle could potentially be utilized as targeting nanocarriers in drug resistant cancer therapy.

Architecture - behaviour - properties relationship in Star-shaped MPA-PMMA and MPA-PS hyper-branched copolymers

Architecture - behaviour - properties relationship in Star-shaped MPA-PMMA and MPA-PS hyper-branched copolymers

Styrene-butadiene branched star-shaped asphalt modifiers: Synthesis and mechanical characterization

The synthesis and the corresponding characterization of styrene-butadiene (SB), branched, star-shaped copolymers was investigated as part of a research project on asphalt modification using polymers with precise molecular structures. The method of anionic polymerization was followed to prepare samples of block copolymers of SB, a synthesis method that controls chain-architecture, molecular weight distribution, monomer distribution, and the average molecular weight. The research studies are the synthesis of block copolymers including linear, three- and four-arms constructs, depending on the coupling agent used. The techniques of nuclear magnetic resonance (1NMR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and rheology were carried out to characterize the copolymers. From the results of the 1NMR, DSC, and GPC analyses, all star-shaped copolymers investigated showed a similar block copolymer composition. Furthermore, the rheological behavior of one of the synthesized star-shaped copolymers was nearly the same as a four-branched commercial copolymer. Rheologically, the four-arm block copolymer sample had the largest storage modulus (G′) among the branched copolymers synthetized, indicating that such architecture produces a highly structured material. In regard to polymer-modified asphalt formulations, the three-branched copolymer architecture yielded better elastic behavior than the four-branch version. In summary, the findings of this investigation provide new insight about a polymer system that may offer advantages in industrial asphalt paving applications.

Synthesis and evaluation of injectable thermosensitive penta-block copolymer hydrogel (PNIPAAm-PCL-PEG-PCL-PNIPAAm) and star-shaped poly(CL─CO─LA)-b-PEG for wound healing applications.

Loss of skin integrity due to injury, burning, or illness makes the development of new treatment options necessary. Skin tissue engineering provides some solutions for these problems. The potential of a biodegradable star-shaped copolymer [Poly(CL─CO─LA)-b-PEG] and penta-block copolymer hydrogel (PNIPAAm-PCL-PEG-PCL-PNIPAAm) was assessed for skin tissue engineering applications. Two copolymers were synthesized for cellular culture scaffolds and their mechanical properties were compared. The resulting star-shaped copolymer and thermosensitive penta-block copolymer were characterized using Fourier transform infrared and nuclear magnetic resonance spectroscopy. The crystallizability of the two copolymers wasanalyzed using X-ray diffraction. The resulting thermosensitive penta-block copolymer was evaluated by differential thermal analysis, differential scanning calorimetry and thermogravimetric analysis. Scanning electron microscopy and in vitro degradation of the polymer network in phosphate buffer solutions (pH 7.4) at 37°C were also examined. The pore size of the gels was calculated with Image Analyzer software. Finally, the cytotoxic, morphological, and gene expression effects of copolymers on the skin fibroblast were evaluated. The experiments showed that the PNIPAAm-PCL-PEG-PCL-PNIPAAm polymer with the right composition and the expected molecular weight wasachieved. The hydrogel had less crystallizability compared with its precursors. The resulting thermosensitive hydrogel had a three-dimensional structure with interconnected pores that mimicked the extracellular matrix. The control of the degradability rate can be possible by weight percent changes. The pore size correlated with the polymer concentration in aqueous solution and the pore sizes of the 20 wt% hydrogel were better for fibroblast cultivation than those of the 10 wt% hydrogel. Cell proliferation on the 20% gel was more than that of the 10% gel. The hydrogel not only preservedthe viability and phenotypical morphology of the entrapped cells but also stimulatedthe initial cell-cell interactions and proliferation of fibroblasts. The hydrogel did not influence cell conformation and this property of the polymer underlinedits safety. Cells seeded on this copolymer showed a normal and spearshapeand formed a focal adhesion with the hydrogel surface. Notably, the hydrogel increased collagen I α1 and collagen III mRNAs expression. Due to the low molecular weight and poor mechanical strength of the star-shaped copolymer, it was not considered for fabricationof the scaffolds for wound healing. The biodegradable, biocompatible, injectable and thermosensitive PNIPAAm-PCL-PEG-PCL-PNIPAAm hydrogel in 20 wt% demonstrated a desirable potential for future application as a cell scaffold in skin tissue engineering and wound healing.

Nano-Carriers Based on pH-Sensitive Star-Shaped Copolymers for Drug-Controlled Release.

Polymeric nano-carriers are considered as promising tools in biomedical applications due to multiple attractive characteristics including their low toxicity, high loading capacity, controlled drug release capabilities, and highly tunable chemical properties. Here, a series of pH-sensitive star-shaped copolymers, Ad-P[(EMA-co-MAA)-b-PPEGMA]4, was prepared via electron transfer atom radical polymerization (ARGETE ATRP) and selective hydrolysis. These star-shaped copolymers can be self-assembled into micelles (Dh = 150–160 nm) and their critical micelle concentrations (CMC) were estimated to be 3.9–5.0 mg/L. The pH-sensitiveness of the micelles was evidenced by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The maximal paclitaxel (PTX) loading efficiency (DLC) and entrapment efficiency (EE) were 18.9% and 36%, respectively. In vitro release studies revealed that about 19% of the PTX released at an acidic condition of pH 1.2 over 70 h, whereas more than 70% was released within the same time interval at pH 6.8. In vitro cytotoxicity suggested that the low cytotoxicity of the blank micelles, while the PTX-loaded micelles providing the cytotoxicity close to that of free PTX. These results indicated that this novel pH-sensitive nano-carriers have great potential applications for oral drug-controlled release.

Synthesis and characterization of amphiphilic star-shaped copolymers based on β-cyclodextrin for micelles drug delivery

Purpose: A series of β-CD amphiphilic star-shaped copolymers with exceptional characteristics were synthesized and their potential as carriers for micelles drug delivery was investigated.Methods: A series of amphiphilic copolymers based on β-CD were synthesized by introducing poly (acrylic acid)-co-poly(methyl methacrylate)-poly (vinyl pyrrolidone) or poly (acrylic acid)-co-poly(methyl methacrylate)-co-poly(monoacylated-β-CD)-poly (vinyl pyrrolidone) blocks to the primary hydroxyl group positions of β-CD. The micellization behavior of the copolymers, the synthesis conditions, characteristics, drug release in vitro and tissue distribution of vinpocetine (VP) micelles in vivo were investigated.Results: Around 60 types of β-CD amphiphilic star-shaped copolymers were successfully synthesized and the critical micelle concentration ranged from 9.80 × 10−4 to 5.24 × 10−2g/L. The particle size, drug loading and entrapment efficiency of VP-loaded β-CD-P4 micelles prepared with optimal formulation were about 65 nm, 21.44 ± 0.14%, and 49.05 ± 0.36%, respectively. The particles had good sphericity. The cumulative release rates at 72 h of VP-loaded β-CD-P4 micelles in pH 1.0, pH 4.5, pH 6.5, or pH 7.4 media were 93%, 69%, 49%, and 43%, respectively. And, the lung targeting efficiency of VP-loaded β-CD-P4 micelles was 8.98 times higher than that of VP injection.Conclusion: The VP-loaded β-CD-P4 micelles exhibited controlled-release property, pH-induced feature and lung targeting capacity compared with VP injection, suggesting that the β-CD-P4 copolymers are an excellent candidate for micelles drug delivery.

Degradable multi(aryl azide) star copolymer as universal photo-crosslinker for elastomeric scaffolds

Degradable elastomers with elastic properties close to those of soft tissues are necessary for tissue engineering. Most degradable elastomers developed so far are based on functional low–molecular-weight prepolymers that are combined with molecular crosslinkers to yield the elastomeric three-dimensional networks. To overcome this limitation, we present in this work the concept of star-shaped macromolecular multi(aryl azide) photo-crosslinker that has the ability to efficiently cross-link any polymer containing C-H bonds independently of its molecular weight and without the need for prefunctionalization. This concept of universal crosslinking agent is illustrated with a star-shaped block copolymer composed of an 8-arm poly(ethylene glycol) core and poly(lactide) side arms functionalized with aryl azide moieties (PEG8arm-PLA-fN3). It was selected due to its macromolecular nature that allows for an easy processing of electrospun photo-crosslinked scaffolds, while making it possible to adapt its chemical nature with one of the polymer matrices. A parameter study is first carried out on PEG8arm-PLA-fN3/PLA-Pluronic®-PLA films to evaluate the impact of the polymers' molecular weight, PEG/PLA ratios, and UV irradiation conditions on the crosslinking efficiency. This study confirms that high crosslinking efficiencies can be obtained with PEG8arm-PLA-fN3 (60%) compared with commercially available bis(aryl azide) photo-crosslinker (below 15%). Optimal conditions are then used to yield electrospun microfibers (1–2 μm) crosslinked with PEG8arm-PLA-fN3, resulting in biocompatible and highly elastomeric scaffolds (εy>100%) compared with uncrosslinked scaffolds (εy<10%). In addition, we show that the degradation rate can be controlled overtime depending on the blend content of PEG8arm-PLA-fN3. Taken together, these results demonstrate the potential of macromolecular multi(aryl azide) photo-crosslinkers to develop original degradable elastomeric scaffolds for soft tissue reconstruction.

Self-assembling water-soluble polymethacrylate-MTX conjugates: The significance of macromolecules architecture on drug conjugation efficiency, the final shape of particles, and drug release.

Water-soluble polymer-methotrexate (MTX) conjugates were obtained via efficient carbodiimide-mediated amidation (E = 17-100%). Binding abilities between water-soluble V-shaped or star-shaped copolymers and MTX were studied by isothermal titration calorimetry spectroscopic (UV-vis, NMR) and microscopic (scanning electron microscopy and transmission electron microscopy) techniques. The efficiency of the amidation reaction has depended on the amount of pendant amino alcohol groups and zeta potential (ZP) values of polymeric carries. The sizes of aggregates formed by polymer-drug conjugates in water increased with the number of copolymer arms (202-774 nm at 37°C). Moreover, the conjugates with the high amount of bounded MTX molecules (nMTX > 78) exhibited negative ZP values. The drug release experiments revealed that the amount of the released MTX depends on pH and can be controlled via shape, topology, and composition of polymeric carrier. Preliminary cytotoxicity studies of V-shaped-MTX conjugate on human immortalized nontumorigenic keratinocyte (HaCaT) cells indicated cytocompatibility of the compound in a wide range of concentrations. The results of our studies have shown that physicochemical and drug release properties of obtained polymer-MTX prodrugs can be tailored via the structure and the topology of the polymeric carrier. Thus conjugates might find the application in a different type of treatment (cancer or psoriasis therapy) and administration (intravenous, dermal, or pulmonary). © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2476-2487, 2019.

Synthesis of an Acrylamide Copolymer Containing Nano-SiO2 by Ex Situ Cu(0)-Mediated SET-LRP

We report herein the synthesis of a novel star-shaped copolymer containing nano-SiO2 by single-electron transfer living radical polymerization (SET-LRP) in aqueous solution. The effects of polymerization conditions, such as the total amounts and molar ratios of the monomer, initiator, catalyst, ligand, and modified nano-SiO2, have been investigated through a series of experiments. The prepared acrylamide copolymers have been characterized by FTIR spectroscopy and 1H NMR spectrometry. The properties of the copolymers have been assessed by viscometry and rheometry. The results confirmed that the nano-SiO2 functional monomer was successfully combined in the SET-LRP. The optimum polymerization conditions were established through orthogonal experiments as a ratio of [AM] : [DMAEMA] : [I] : [CuBr] : [Me6TREN] of 674.4 : 35.5 : 1 : 1 : 2 at a total concentration of [AM] + [DMAEMA] of 2.5 mol/L. The appropriate concentration of the nano-SiO2 functional monomer (NSFM) was 0.5 wt% with respect to AM + DMAEMA. The rheology of the star-shaped copolymer exhibited a shear-thickening property when the shear rate exceeded a critical value (100 s−1). The AM/DMAEMA/NSFM copolymer displayed a higher viscosity than AM/DMAEMA at the same concentration. It was found that AM/DMAEMA/NSFM exhibited better salt and temperature tolerances.

Evaluation of the resistance to bacterial growth of star-shaped poly(ε-caprolactone)-co-poly(ethylene glycol) grafted onto functionalized carbon nanotubes nanocomposites

Nanocomposites of functionalized carbon nanotubes (CNTsf) as nanofillers, and a copolymer of star-shaped poly(ε-caprolactone) (stPCL) and poly(ethylene glycol) (PEG) as a polymeric matrix were synthesized, characterized, and their resistance to the growth of Staphylococcus aureus and Pseudomonas aeruginosa was evaluated. CNTsf contain hydroxyl, carboxyl and acyl chloride groups attached to their surface. Nanocomposites were prepared by mixing CNTsf to a solution of stPCL-PEG copolymer. Raman and FT-IR spectroscopies confirm the functionalization of carbon nanotubes (CNTs). Star-shaped PCL-PEG copolymer was characterized by Gel permeation chromatography (GPC), and 1H-NMR and 13C-NMR spectroscopies. X-ray photoelectron spectroscopy (XPS) shows that CNTsf are grafted to the stPCL-PEG copolymer. Crystallization behavior of the nanocomposites depends on the amount of CNTsf used in their preparation, detecting nucleation (nanocomposites prepared with 0.5 wt.% of CNTsf) or anti-nucleation (nanocomposites prepared with 1.0 wt.% of CNTsf) effects. Young’s Moduli and thermal stability of nanocomposites were higher, but their resistence to the proliferation of Staphylococcus aureus and Pseudomonas aeruginosa was lower than the observed for their pure polymer matrix.

Star-Shaped Block Copolymers: Effective Polymer Gelators of High-Performance Gel Electrolytes for Electrochemical Devices.

Ion gels composed of copolymers and ionic liquids (ILs) have attracted great interest as polymer gel electrolytes for various electrochemical applications. Here, we present highly robust ion gels based on a six-arm star-shaped block copolymer of (poly(methyl methacrylate)- b-polystyrene)6 ((MS)6) and an ionic liquid of 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide ([EMI][TFSI]). Compared to typical ion gels based on linear polystyrene- b-poly(methyl methacrylate)- b-polystyrene (SMS), the (MS)6-based gels show mechanical moduli of more than twice under various strains (e.g., stretching, compression, and shear). In addition, the outstanding mechanical property is maintained even up to 180 °C without a gel-sol transition. To demonstrate that (MS)6-based ion gels can serve as effective gel electrolytes for electrochemical applications, tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)32+), a representative electrochemiluminescent (ECL) luminophore, is incorporated into the gels. In particular, flexible ECL devices based on (MS)6 gels exhibit high durability against bending deformation compared to devices with gels based on linear SMS having a similar molecular weight and a composition. This result implies that star-shaped block copolymers are effective gelators for achieving flexible/wearable electrochemical electronics.