PEG Segments Research Articles

In situ preparation of hetero-polymers/clay nanocomposites by CUAAC click chemistry.

A series of polymer/clay nanocomposites containing mechanistically two different polymers, poly(ethylene glycol) (PEG) and poly(epsilon caprolactone) (PCL), were prepared by simultaneous copper(I)-catalyzed alkyne-azide cycloaddition click reactions. Both clickable polymers, PEG-Alkyne and PCL-Alkyne, were simultaneously clicked on to azide-functional montmorillonite (MMT-N3) nanoclay to get corresponding PEG-PCL/MMT nanocomposites. The chemical structures of the resulting nanocomposites were verified by following azide and silicone-oxygen bands using FT-IR and characteristic bands of PEG and PCL segments using 1H-NMR spectroscopy. The combined XRD and TEM analysis confirmed that all PEG-PCL/MMT nanocomposites had partially exfoliated/intercalated morphologies. In addition, the increase of MMT-N3 loading not only improved the onset and maximum degradation temperatures of the nanocomposites but also their char yields. Furthermore, the incorporation of MMT-N3 in the polymer matrix did not significantly influence the crystallization behavior of both PEG and PCL segments.

Influence of miscible and immiscible sequences of poly(D-lactide) copolymers on the competition of stereocomplex- and homo-crystallization in poly(L-lactide) blends

A high molecular weight (HMw) PLLA has been blended with a low molecular weight (LMw) PDLA and its two types diblock copolymers (PEG-b-PDLA and PDMS-b-PDLA), respectively, to investigate the stereocomplex (sc) and homochiral (hc) crystallization behaviors. The miscible PEG and immiscible PDMS segments with comparable molecular weight were introduced into PDLA by bulk ring-opening polymerization method. Compared to PLLA/PDLA, the introduction of both sequences could inhibit the crystallization kinetics of sc and hc crystallites of the blends due to the dilution effect of LMw segments. The formation of sc crystallites is prior to its hc counterparts. The shorter induction period of hc crystallites of PLLA/PEG-b-PDLA blend indicates that the miscible PEG segments could promote the mobility of PLLA chains. Due to the involving of PEG chains, the spherulite exhibits coarsen and irregular texture and its lamellae show sparse string-like structure. The microphase separation between PLA and PDMS segments as evidenced by SAXS results in the increased sc nuclei and different growth mode of hc crystallites. The phase separated microdomains weakened the competition between sc and hc crystallites, and the former acts as a template for repeated assembly of the latter. X-ray analysis also reveal that sc crystallites possess much thicker lamellar thickness than hc crystallites in PLLA/PDLA and PLLA/PEG-b-PDLA blends.

Aggregation-Induced Emission-Active Fluorescent Polymer: Multi-Targeted Sensor and ROS Scavenger.

A multi-functional polymer with aggregation-induced emission (AIE)-active salicylaldehyde azine (SA) functionality and reactive oxygen species (ROS)-responsive thioether groups is readily prepared via thiol-ene click polymerization of SA derivative diacrylate monomer, poly(ethylene glycol) diacrylate, and 3,6-dioxa-1,8-octanedithiol. The obtained AIE-active polymer exhibited an unexpected strong emission in amide solvents compared to that in other common organic solvents that was dramatically decreased by adding a trace amount of water, suggesting that the polymer could be utilized as a water trace indicator in amide solvents. In the backbone, the PEG segments make the polymer well dispersed in water and the ROS-responsive thioether groups enable this polymer as a promising ROS scavenger, with embedded SA moieties as a fluorescent indicator for the hemolysis determination. Due to the ability of SA moieties to complex with Cu2+, this AIE polymer can also be utilized as a fluorescent sensor for selective Cu2+ detection in real-world water samples. Thus, this multi-functional polymer is anticipated to be well applied in biological and environmental applications.

Sulfonamide functionalized amino acid‐based pH‐ and temperature‐sensitive biodegradable injectable hydrogels: Synthesis, physicochemical characterization and in vivo degradation kinetics

AbstractIn this research, a novel pH and temperature‐sensitive biodegradable oligomer serin‐b‐poly(lactide)‐b‐poly (ethylene glycol)‐b‐poly(lactide)‐b‐ oligomer serin (OS‐PLA–PEG–PLA‐OS) pentablock copolymer was synthesized with modification of serine to sulfonamide group. The properties of the different pentablock copolymer structures were detail characterized. The copolymer solution easily flowed at high pH and changed to gel state at physiological conditions (37°C, pH 7.4). The sol to gel behavior of these block copolymer solutions were controllable by tuning the length of PEG segment, PLA/PEG block ratio, the molecular weight and the concentration of the pentablock copolymer. The in vivo gelation of the copolymer solution was investigated. The stable gel was formed after injection into the back of the adult male Mus musculus Swiss Albino mice. The degradation process was observed after 6 weeks and showed that the hydrogel depot was bioresorbable without any detection of inflammation sign. The results in this study suggest that the OS‐PLA–PEG–PLA‐OS pentablock copolymer has the potential application as an injectable delivery vehicle for therapeutic drugs that easily denatured at low‐pH condition.

Thermal Properties and Self-Assembly Behaviors of Triblock Copolymers Consisting of PEG Segment and Acrylamide-Based Block Bearing Alkyl Side Chains Prepared by RAFT Method

A new series of hybrid triblock copolymers (TBCs) based on hard–soft–hard segments are synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization using a macroinitiator p...

Fabrication and characterization of high flux poly(vinylidene fluoride) electrospun nanofibrous membrane using amphiphilic polyethylene‐block‐poly(ethylene glycol) copolymer

AbstractElectrospun nanofiber membranes (ENM) made of polymers such as polysulfone and poly(vinylidene fluoride) (PVDF) have a much higher contact angle (CA) and also more hydrophobic when compared to the virgin polymers. For water treatment applications, membranes with hydrophilic nature are highly desirable in order to achieve high flux and less fouling potentials. Hence, in the present study, highly hydrophilic electrospun nanofiber membranes (ENMs) were prepared by blending PVDF polymer with amphiphilic polyethylene‐block‐poly (ethylene glycol) (PE‐b‐PEG) copolymer. Resulting amphiphilic ENMs were highly porous (77%–92%) and the breaking elongation of 140% with a young's modulus of 2.55 MPa was observed. When compared with the control PVDF membrane, PE‐b‐PEG blended ENMs revealed higher water permeation flux owing to the enrichment of the hydrophilic PEG segments at the membrane surface, which was confirmed by using X‐ray photoelectric spectroscopy and Energy‐dispersive spectroscopy measurements. When compared to the phase inversion process (CA of 97.3°) blended ENM had CA of 0°, which indicates that besides hydrophilic block copolymer segments, the nature of membrane formation also contributes its role in influencing the hydrophilicity of the membrane. This improved hydrophilicity in combination with larger pore sizes of the PVDF/ PE‐b‐PEG membranes have contributed to enhancement of pure water flux, protein solution permeability and water flux recovery, which can be applied potentially for water treatment applications.

(AB)n Segmented Copolyetherimides for 4D Printing

AbstractThe fourth dimension in 4D printing comprises the ability of materials to recover their shape with time by utilizing 3D printing in combination with shape memory polymers. The focus of this work is on 3D printing of physically crosslinked thermoplastic polymers, which allow a reversible transformation from a temporary to an original shape by an external stimulus temperature, thus realize 4D printing. In this context, (AB)n segmented copolyetherimides consisting of perylene and poly(ethylene glycol) (PEG) segments are synthesized and characterized regarding their thermal and rheological properties in view of 3D printing. The perylene imide segments act as reversible physical crosslinks which disassemble between 100 and 200 °C. The PEG segments exhibit a low melting temperature around 40 to 60 °C and are semi‐crystalline at room temperature. The results show that this type of (AB)n segmented copolyetherimide combines reliable 3D printing performance, which is indicated by low warp deformation and excellent interlayer bonding. With a blend of two copolymers, it is able to realize 4D printing.

Synthesis of Poly(ether‐ester‐urethane) with a Controlled Molar Mass Based on Poly(ε‐caprolactone) and Poly(ethylene glycol) Segments

AbstractPoly(ether‐ester‐urethanes) (PEEUs) derived from poly(ε‐caprolactone) and poly(ethylene glycol) (PCL‐b‐PEG) have a high potential for use in biomedical applications or as compatibilizers of immiscible poly(acid lactic) and poly(ε‐caprolactone) (PLA/PCL) blends. This study focused on the synthesis of PEEUs with same molar mass by one‐step bulk polycondensation of PCL and PEG macrodiols and hexamethylene diisocyanate (HDI). The copolymers, distinguished by the size of hydrophilic PEG and hydrophobic PCL segments and symmetry of the blocks, are characterized by SEC, FTIR, H1‐NMR, TGA, DSC, and water absorption testing. FTIR and H1‐NMR results demonstrated the formation of a hydroxy‐terminated multiblock copolymer with urethane bonds. Additionally, the PEG:PCL compositions measured by H1‐NMR are close to the theoretical compositions. Molar mass distribution curves revealed that copolymers with molar mass around 45 000 Da are synthesized by varying extents of ratio, given by NCO/OH molar ratio, between 0.9 and 1.0 depending on the initial macrodiols molar masses. The block size ratio of hydrophilic and hydrophobic blocks is an important parameter in water absorption behavior, which can generate a water‐uptake of 50% or even 350% depending on the symmetry of the segments.

Temperature-induced structural changes of biocompatible crystallizable rosin polymer in solution and hydrogel

In this work, the structural changes of amphiphilic polymer polyethylene glycol-acrylicpimaric acid-polyethylene glycol (PEG-APA-PEG) were studied through dynamic light scattering (DLS), rayleigh light scattering (RLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technologies in a heating and cooling run. Reversible micelle to aggregation structural change was observed as the concentration was above critical micelle concentration (CMC). The structural changes including multi-chain clusters, self-seeding, disaggregate, fusion, scission and corona crystallization were thoroughly revealed as concentration was closed to or lower than CMC. In addition, the crystallization behavior and mechanism of PEG-APA-PEG polymer in solution were revealed by X-ray diffraction (XRD), Differential scanning calorimetry (DSC) and Polarized optical microscopy (POM). The acrylicpimaric acid segments formed seeds at 85 °C and the PEG corona crystallized below 25 °C. Gel–sol transition of PEG-APA-PEG occurred at 8 °C during heating were governed via the crystallization of PEG segment at 5 °C. The rosin copolymer possessing good hemocompatibility and biocompatibility might potentially was used for biomedical material.

"All-inclusive" silicon nanoparticles for sensitive detection of blood glucose

In this study, a success is achieved in developing a new variety of "all-inclusive" silicon nanoparticles with recognition components of boronic acid groups and anti-fouling components of PEG segments for the precise detection of glucose. The added glucose will contribute to the significant fluorescence quenching of "all-inclusive" silicon nanoprobes. Not only does this method achieve the accurate detection of glucose in the range of 0.4 to 10 μM with a detection limit of 0.27 μM, it is also applicable to the clinical analysis of blood glucose.

Some Guidelines for the Synthesis and Melting Characterization of Azide Poly(ethylene glycol) Derivatives.

We provide fundamental guidelines in the form of a tutorial to be taken into account for the preparation and characterization of a specific class of poly(ethylene glycol) (PEG) derivatives, namely azide-terminated PEGs. Special attention is given to the effect of these chain end groups and their precursors on properties affecting the PEGylation of proteins, nanoparticles and nanostructured surfaces. Notwithstanding the presence of 13C satellite peaks, we show that 1H NMR enables not only the routine quantitative determination of chain-end substitution, but is also a unique method to calculate the absolute number average molecular weight of PEG derivatives. In the use of size exclusion chromatography to get molecular weight distributions, we highlight the importance of distinguishing between eventual secondary reactions involving molecular weight changes and the formation of PEG complexes due to residual amounts of metal cations from reactants. Finally, we show that azide end groups affect PEG melting behavior. In contrast to oxygen-containing end groups, azides do not interact with PEG segments, thus inducing defect formation in the crystal lattice and the reduction of crystal sizes. Melting temperature and degree of crystallinity decrease become especially relevant for PEGs with very low molecular weight, and its comprehension is particularly important for solid-state applications.

An AIE polymer prepared via aldehyde-hydrazine step polymerization and the application in Cu2+ and S2− detection

Herein we reported the synthesis of a novel amphiphilic AIE (aggregation-induced emission) polymer with salicylaldehyde azine (SA) moieties and PEG segments in the backbone via the aldehyde-hydrazine step polymerization. The polymer can self-assemble into stable micelles in water at ambient temperature and display intense orange fluorescence because of the aggregation of SA moieties in the core. Moreover, the polymer was found to be thermoresponsive with a relatively high LCST (lower critical solution temperature) and the LCST can be tuned via the chain length of PEG segments. The polymer micelles formed at ambient temperature can serve as a turn-off fluorescent probe for the selective detection of Cu2+ in aqueous media with a low detection limit of 53 nM. The fluorescence of polymer can be completely quenched by Cu2+ and the formed polymer-Cu2+ complex can be used as a turn-on fluorescent probe for the selective detection of S2− with a detection limit of 0.24 μM. The polymer is expected as a useful fluorescent probe for the selective detection of Cu2+ and S2− in environmental field.

Morphological transition of amphiphilic block copolymer/PEGylated phospholipid complexes induced by the dynamic subtle balance interactions in the self-assembled aggregates

Abstract Recently, there has been an increasing interest in the control of morphological transition of block copolymer aggregates. Here, we report how to control the morphological transition of methoxy polyethylene glycol–poly(d,l-lactic acid) (PDLLA–MPEG) by adding 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)] (DSPE–PEG). In the aggregates formed by dialyzing DSPE–PEG/PDLLA–MPEG mixed solutions against water, the two hydrophobic fatty acid tails of DSPE–PEG will preferentially anchor to the hydrophobic segment end of PDLLA–MPEG by interdigitating between these two tails and PDLLA segments. Consequently, DSPE–PEG and PDLLA–MPEG will form “ABA” temporary supra-amphiphiles in which A represents a poly(ethylene glycol) (PEG) chain segment and B is a mixed hydrophobic segment composed of PDLLA and DSPE segments; the repulsive force derived from the PEG segments of DSPE–PEG can affect the stability of “ABA” temporary supra-amphiphiles. Our results show that the dynamic subtle balance between the number of “ABA” temporary supra-amphiphiles formed and the strength of repulsive force between the PEG segments of DSPE–PEG drives the morphological structure of DSPE–PEG/PDLLA–MPEG aggregates to change from micelles to vesicles, then to semi-vesicles and finally to mixed micelles, with increasing DSPE–PEG additions.

Cationic Block Copolymer Nanoparticles with Tunable DNA Affinity for Treating Rheumatoid Arthritis

AbstractA high concentration of cell‐free DNA (cfDNA) in joints is considered a disease causative agent of rheumatoid arthritis (RA) and cfDNA scavenging has been regarded as an efficient therapeutic avenue. Cationic polymers can hamper progression of joint inflammation in a rat model of RA by scavenging cfDNA; however, they may cause systemic toxicity due to the strong positive charges. To reduce the toxicity, herein a library of cationic nanoparticles (cNPs) of block copolymer micelles is developed and the effects of structure and surface composition on cNP efficacy to bind nucleic acids, toxicity, and therapeutic activity on a collagen induced arthritis (CIA) rat model of RA are assessed. The library includes cNPs with a homoshell from poly(lactic‐co‐glycolic acid)‐block‐poly(2‐(dimethylamino)ethyl methacrylate) (PLGA‐b‐PDMA) block copolymers and cNPs with a mixed shell of poly(ethylene glycol) (PEG) and PDMA by coself‐assembling PLGA‐b‐PDMA and PLGA‐b‐PEG block copolymers. Relatively to the homoshell cNPs, introduction of PEG segments translates into a lower DNA binding efficacy while preserving ability to hamper joint inflammation. Moreover, they show a greater accumulation and longer retention at the inflamed joints, allowing a lower administration frequency. In conclusion, this work shows that the therapeutic index of cationic materials can be tuned by introducing surface neutral moieties.

Towards permanent hydrophilic PVDF membranes. Amphiphilic PVDF-b-PEG-b-PVDF triblock copolymer as membrane additive

Poly(vinylidene fluoride) (PVDF) ultrafiltration membranes were prepared by non-solvent-induced phase separation (NIPS) using a blend of a new amphiphilic PVDF-based triblock copolymer (PVDF-b-PEG-b-PVDF) and high molar mass PVDF. During the phase inversion step, the triblock copolymer acts both as a pore forming and surface modifying agent. Thanks to the presence of the short PVDF blocks in the triblock copolymer, the hydrophilic PEG segment is fixed in the PVDF matrix, thus reducing the gradual loss of hydrophilic additive by leaching of the triblock copolymer out of the membrane matrix. The PVDF-b-PEG-b-PVDF triblock copolymer additive improved the surface hydrophilicity and significantly increased the pure water flux and permeability of the PVDF membrane. The membrane composition was optimized in terms of additive concentration and compared to membranes prepared with an equivalent amount of commercial PEG of similar molar mass. Pure water filtration tests and contact angle measurements suggested that addition of small amounts of the triblock copolymer additive (2–5% w/w) has a strong impact on the performance and hydrophilic characteristic of the PVDF membranes. The control tests showed that less than 30% w/w of the additive is lost after 9 months, while most commercial PEG (59% w/w) leached out of the membrane matrix in only two months.

Synthesis, thermal properties and rheological behaviors of novel Poly(ethylene glycol) segmented Poly(arylene ether)s

A series of new poly (ethylene glycol) (PEG) segmented poly (arylene ether)s (PAEs), (PEG-PAEs) were synthesized via nucleophilic substitution polycondensation. The prepared PEG-PAEs are thermally stable up to 190 °C, which is dominated by the PEG segments. Their glass transition temperature (Tg) points are in the range of -10 - 32 °C, which is dictated by the molecular weights as well as the fraction of PEG segments in the structures. And the materials are in an amorphous state due to the steric hindrance imposed by F1 segments. The rheological measurement reveals that the viscoelastic property of the F-PEG1000 and F-PEG2000 can experience a transition from a glassy state to a leather state and then to a rubbery state after applying the time-temperature superposition (TTS) principle. Moreover, a decreased trend of the complex viscosity is found as the temperature increases, which can be attributed to the accelerated movement of polymer chains at a higher temperature. And the fraction of the PEG segments as well as the molecular weights of the materials can also affect the complex viscosity. Accordingly, the thermal properties and rheological behaviors of the PEG-PAEs can be adjusted by selecting different PEG macromonomers.

Dual-Function Antibacterial Micelle via Self-Assembling Block Copolymers with Various Antibacterial Nanoparticles.

Antibacterial biomaterials with kill-resist dual functions by combining multiple active components have been constructed, with a final aim at decreasing the incidence of biomaterial-centered infection. Self-assemblies of bactericidal ZnO or Ag–ZnO nanoparticles (NPs) with triblock copolymers, poly(ethylene glycol)-b-poly(3-hydroxybutyrate-co-3-hydroxyvalerate)–poly(ethylene glycol) (PEG–PHBV–PEG), showed a hydrophobic PHBV layer on NPs with PEG segments exposed outside via hydrogen bonding, resulting in long PEG (Mw = 2000) aggregation and short PEG (Mw = 1000) aggregation, respectively. These nanocomposite aggregations released ZnO or Ag–ZnO rapidly within initial few hours, and about 42–45% of NPs were left in the nanocomposites in deionized water for 16 d to improve the long-term antibacterial activity further. At the concentration below 50 μg/mL, the nanocomposite aggregation was cell-compatible with ATDC5 and showed sterilization rates over 91% against Escherichia coli and 98% against Staphylococcus aureus. Long PEG aggregation showed greater cell proliferation capacity than short PEG aggregation, as well as better bacterial resistance and bactericidal activity against both E. coli and S. aureus. The flexible self-assembling antibacterial NPs with antifouling block copolymers via adjusting the component ratio or the segment length have shown premise in the construction of the dual-function antibacterial materials.

Unveiling the hydrogen bonding network in liquid crystalline natural-based glycosides containing polymeric complexes: Experimental and theoretical assessment

In this work we present a facile and versatile strategy to prepare new amphiphilic compounds obtained from natural sources, avoiding costly covalent synthetic stages, and we introduce a powerful methodology to describe hydrogen-bonding networks in carbohydrates liquid crystals A series of new glycosides has been prepared by mixing a natural-based mannoside, αManPKO, with three different polymeric substrates: poly(ethylene oxide), PEG, poly(4-vinyl pyridine), P4VP, and a block-copolymer containing PEG and P4VP segments, PEG45-b-P4VP18. The materials have been characterised by differential scanning calorimetry, polarised optical microscopy and small-angle X-ray diffraction. The resulting complexes are assembled by hydrogen-bonding and form smectic A phases, with the polymeric chains spread along the surface of the glycosides bilayers. By using Fourier-transform infrared spectroscopy, FT-IR, and molecular simulations, we have assessed the selectivity of the hydrogen bonds formed between αManPKO and the polymeric segments. Our results suggest that the assembly of the polymeric complexes must be explained by a combination of interfacial mixing between the polymer/glycoside units at the bilayer boundaries (favoured by PEG) and the formation of strong hydrogen bonds (favoured by P4VP).

Synthesis of well‐defined block copolymer composed of flexible amphiphilic poly(ethylene glycol) and hydrophobic liquid crystalline segments by living coordination polymerization of allene derivatives and its application to thin film with perpendicularly oriented cylindrical nanostructure

AbstractA block copolymer composed of a flexible polar poly(ethylene glycol) (PEG) and a less polar liquid crystalline poly(allene) segments is prepared by the living coordination polymerization of an allene derivative possessing trans‐azobenzene‐containing mesogenic substituent by the use of a π‐allylnickel macroinitiator bearing PEG segment. The thin film of the block copolymer is prepared by the spin coating of its solution onto mica or silicon wafer which proves to possess perpendicularly oriented nanocylindrical microphase separated structures as supported by the differential calorimetric, polarized optical microscopic, grazing‐incidence small‐angle X‐ray scattering, transmission electron microscope, and atomic force microscope measurements.

IR780-loaded zwitterionic polymeric nanoparticles with acidity-induced agglomeration for enhanced tumor retention

The tumor-targeted delivery of near infrared (NIR)-triggered photothermal therapy (PTT) by varied nanocarriers has captured substantial attention. In order to boost the antitumor efficacy of PTT by promoting cellular uptake and tumor retention of PTT-carrying nanoparticles, the surface charge-changeable polymeric nanoparticles comprising poly(lactic-co-glycolic acid) (PLGA) cores covered with zwitterionic diblock copolymers, methoxypoly(ethylene glycol)-b-poly(methacrylic acid-co-histamine methacryamide), mPEG-b-P(MAA-co-HMA), were developed as vehicles of IR780. Due to the acid-triggered protonation of imidazole groups, the resulting positively charged HMA residues tend to form electrostatic complexes with negatively charged MAA residues, thus facilitating the embedding of outer PEG segments into the neutral and gel-like surfaces and thus the formation of inter-particle aggregation. Taking advantage of the weak acidity of tumor extracellular matrix, the IR780-loaded nanoparticles undergoing acidity-elicited dramatic structural transformation showed appreciably enhanced cellular uptake by TRAMP-C1 cells and prolonged tumor retention time.