PEO PPO Research Articles

Incorporation of Lamotrigine Drug in the PEO–PPO–PEO Triblock Copolymer (Pluronic F127) Micelles: Effect of Hydrophilic Polymers

AbstractThe hydrophobic drug Lamotrigine (LTG) shows low bioavailability after oral administration. Work has been performed to improve the aqueous solubility of LTG using the micelles of amphiphilic block copolymers. Polyethylene oxide‐ polypropylene oxide‐ polyethylene oxide triblock copolymers (PEO–PPO–PEO), known as Pluronic®, have been the subject of current interest due to the versatile structural possibilities of varying PEO/PPO ratios. Incorporation of LTG in the aqueous micellar solutions of Pluronic® F127 was investigated using UV–visible spectroscopy. The shapes and size of the micelles with and without LTG have been ascertained using dynamic light scattering and small angle neutron scattering experiments. Results show increase in the Pluronic® micellar size with hard sphere radius with the incorporation of LTG. The effect of hydrophilic polymers (PEG1500 and F68) on the LTG‐incorporated Pluronic® F127 micelles was also studied and found inefficient for enhancement of the solubility of LTG. Solid forms of LTG‐incorporated Pluronic® F127 micelles with and without hydrophilic polymers, coded as LPMs, were successfully prepared through the thin‐film hydration method. Fourier transform infrared spectroscopy, X‐ray diffraction spectroscopy and thermogravimetric analysis have been used to ensure the compatibility of the LTG with Pluronic® F127 micelles in prepared LPMs. All the LPMs showed good incorporation efficiency, loading capacity and the sustained release profile of LTG. Results showed no specific improvement with the addition of hydrophilic polymers in the studied concentration range.

Nonmigrating Equivalent Substitutes for PVC/DOP Formulations as Shown by a TG Study of PVC with Covalently Bound PEO-PPO Oligomers.

Monoamino functionalized ethylenoxide (EO)/propylenoxide oligomers (Jeffamine) are linked chemically to poly(vinyl chloride) (PVC) using trichlorotriazine chemistry in order to prepare nonmigrating internally plasticized materials. The dependence of the plasticizer efficiency on both the number of anchoring points to the chains and the PVC/plasticizer compatibility is investigated using oligomers of different molecular weight and hydrophilic-hydrophobic balance. Hydrophilic oligomers (containing predominantly EO) of molecular weights between 2000 and 5000 g mol-1 exhibit excellent plasticizer efficiency, nearly identical to di-2-ethylhexylphthalate (DOP) in conventional PVC/DOP mixtures and may therefore be used as nonmigrating equivalents for DOP.

Effect of nucleoside analogue antimetabolites on the structure of PEO-PPO-PEO micelles investigated by SANS.

The effect of three nucleoside analogue antimetabolites (5-fluorouracil, floxuridine, and gemcitabine) on the structure of Pluronic L62 copolymer micelles was investigated using small-angle neutron scattering. These antimetabolites used for cancer chemotherapy have analogous molecular structures but different molecular sizes and aqueous solubilities. It was found that the addition of the three antimetabolites slightly reduced the micellar size and aggregation number, and the micellar anisotropy. The added antimetabolites also changed the internal molecular distribution of the micelles as measured by the scattering length densities, resulting in enhanced hydration of the hydrophobic core region of the micelle. The strength of the effect was found to correlate with the molecular properties of the model drugs, i.e. a larger molecular size and a higher aqueous solubility lead to enhanced hydration of the micellar core.

Amphiphilic electrospun scaffolds of PLLA–PEO–PPO block copolymers: preparation, characterization and drug-release behaviour

Drug-loaded nanofibrous scaffolds containing hydrophilic or hydrophobic drugs presented encapsulation efficiency, distribution and release dependent on copolymer composition.

Reaction‐induced phase separation and resulting thermomechanical and surface properties of epoxy resin/poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) blends cured with 4,4′‐diaminodiphenylsulfone

ABSTRACTWe investigated the phase separation, cure kinetics and thermomechanical properties of diglycidyl ether of bisphenol‐A/4,4′‐diaminodiphenylsulfone/poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) triblock copolymer (TBCP) blends. Fourier transform infrared spectroscopy, differential scanning calorimetry, and atomic force microscopy revealed that the blends exhibited heterogeneous phase morphology in which the TBCP formed dispersed domains in epoxy matrix, due to reaction induced phase separation. A fraction of phase‐separated PEO phase underwent partial crystallization whereas another fraction formed interphases between the dispersed domains and epoxy matrix. Moreover, the dispersed PEO chains improved the compatibility and interfacial adhesion between the matrix and domains and, consequently, significantly improved the mechanical properties of epoxy resin. Furthermore, the thermal degradation studies and contact angle measurements disclosed that the dispersed domains were well protected by the epoxy matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44406.

Phase Behavior and Lubricity of Aqueous PEO-PPO-PEO and PPO-PEO-PPO Triblock Copolymer Solutions

ABSTRACTAqueous triblock copolymer solutions are potential low-cost, eco-friendly lubricants. However, as a solution, their phase changes with copolymer concentration and solution temperature, raising the question, “Does the phase change affect the formation of adsorbed layer and the lubrication performance?” This article studies the copolymer solution phase behavior and lubricity in response to the copolymer structure, concentration, and solution temperature. Four different triblock copolymers, two normal PEO-PPO-PEO and two reverse PPO-PEO-PPO composed of PEO poly(ethylene oxide) and PPO poly(propylene oxide), have been investigated. From cloud point and surface tension measurements, phase change and micellization are shown to depend on copolymer type, number of hydrophilic PEO blocks, and temperature. Furthermore it is found that the phase and the presence of micelles lead to significant variation in adsorbed copolymer mass and lubricity. Based on the observed phase behaviors, the lubricity of copolymer solutions is discussed with regard to aggregation and adsorption on the solid–liquid interface.

A novel pH-induced thermosensitive hydrogel composed of carboxymethyl chitosan and poloxamer cross-linked by glutaraldehyde for ophthalmic drug delivery

In this work, a stimuli-responsive three dimensional cross-linked hydrogel system containing carboxymethyl chitosan (CMC) and poloxamer composed of a poly (ethylene oxide)/poly (propylene oxide)/poly (ethylene oxide) (PEO–PPO–PEO) block copolymer was constructed, and its aqueous solution was found to undergo a reversible sol-gel transition upon a temperature and/or pH change at a very low concentration. The hydrogels were synthesized via a cross-linking reaction using glutaraldehyde (GA) as the cross-linking agent. The structures of the hydrogels were characterized by FTIR, XRD, NMR and SEM studies and the swelling behaviour was studied in different buffered solutions. The results obtained indicated that cross-linked F127-CMC underwent discontinuous phase transition in different temperature and pH solutions. The hydrogels at 35°C and pH 7.4 were found to have larger pores than at the other three conditions which resulted in greater swelling. The result of rheological studies showed that the gelation temperature was 32–33°C and the viscosity of the hydrogel increased quickly after gelation. In an addition, the cytotoxicity and in vitro release was studied at different pH values and temperature. The results of a CCK-8 (Cell Counting Kit-8) assay showed that the hydrogel and its physical mixture solution were not cytotoxic to human corneal epithelial cells at a low concentration. Using the drug nepafenac (NP) as a model drug, the controlled drug release behaviour of these hydrogels was investigated. Owing to the formation of F127-CMC/NP retarding the diffusion rate of NP, a sustained release of NP from the hydrogel can be obtained. The release rate was found to be maximum at 35°C and pH 7.4. From these preliminary evaluations, it is possible to conclude that the hydrogels have an excellent potential for application in ophthalmic drug delivery systems.

Modeling the interfacial properties of Poly(Ethylene oxide-Co-Propylene oxide) polymers at water-toluene interface

Understanding how the structure of demulsifiers affects its interfacial properties is essential to developing new demulsifiers with desired properties. Modeling is an important tool to methodically study the effect of polymer architecture on its microscopic structure and macroscopic properties. Here modified interfacial Statistical Associating Fluid Theory (iSAFT) was used to study the interfacial properties of additives at water-toluene interface. The density profile, surface adsorption and interfacial tension (IFT) was predicted for different architectures of poly (ethylene oxide-co-propylene oxide) (PEO-PPO) at the interface. The predicted IFT was validated against experimental data (for Pluronics, Tetronics and Poloxamer) and the theory was found to be in good agreement with experiments. The effect of molecular weight, branching, PEO:PPO ratio and ordering of the PEO and PPO blocks was studied. It was found that IFT was lowest for high molecular weight and highly branched polymers and the IFT curve went through a minima with varying PEO:PPO ratio. The hydrophilic PEO block on the outside and hydrophobic PPO block as the inside block led to more interfacial adsorption and lowering of IFT compared to the reverse polymer (PPO outside and PEO inside).

Fabrication of TEOS/PDMS/F127 hybrid coating materials for conservation of historic stone sculptures

The present work was aimed to develop a new kind of stone conservation materials (TEOS/PDMS/F127 hybrid coating) by a facile sol–gel method for the protection of decayed sandstones of Chongqing Dazu stone sculptures in China. The hydrophobic property, surface morphology, water vapor permeability, ultraviolet aging resistance and mechanical properties were measured to evaluate the effectiveness of TEOS/PDMS/F127 hybrid coating as a stone conservation material. The results showed that the addition of hydroxyl-terminated polydimethylsiloxane (PDMS-OH) contributed to improve the hydrophobic properties and incorporation of PEO–PPO–PEO (F127) surfactant resulted in the formation of superficial protrusions with micro- and nanoscopic structures and overall alteration of surface morphology and roughness, thus preventing the coating materials from cracking. After treatment with TEOS/PDMS/F127 hybrid coating materials, the ultraviolet aging resistance and mechanical properties of stone were also improved without the obvious effects on the breathability and color of the stone, indicating promising applications of TEOS/PDMS/F127 hybrid coating materials for conservation of historic stone sculptures.

A cell-compatible PEO–PPO–PEO (Pluronic®)-based hydrogel stabilized through secondary structures

Pluronic F-127 (PF127) is a thermosensitive polymer that has been widely recognized as a potential candidate for various bio-applications. However, in hydrogel form, its rapid disintegration and inhospitality toward cells have significantly limited its usage. As a means to increase the integrity and cell compatibility of a PF127 hydrogel, we propose the introduction of stabilizing secondary structures to the gel network by the addition of secondary structure-forming oligo-alanine and oligo-phenylalanine. Results indicate that increasing the oligo(peptides) attached to PF127 led to a significant decrease in the gelation concentration and temperature. A selected oligo(peptide)-modified PF127 was capable of forming a stable hydrogel network at 5% and suffered only 20% weight loss after 7days of incubation in media. Scanning electron microscopy (SEM) revealed comparably more interconnected morphology in modified hydrogels which may be attributed to the presence of secondary structures, as verified by circular dichroism (CD) and Fourier-transformed infrared (FT-IR) spectroscopy. Nuclear magnetic resonance (NMR) provided insights into the extensive interactions at the micelle core, which is the key to altered gelation behavior. Furthermore, modified hydrogels maintained structural integrity within culturing media and supported the proliferation of encapsulated chondrocytes. In addition, in vivo residence time was extended to well beyond 2weeks after oligo(peptide) modification, thereby broadening the application scope of the PF127 hydrogel to encompass long-term drug delivery and cell culturing.

In Situ Cavitation of Phenolic Supramolecules with PEO–PPO–PEO Block Copolymers by Friedel–Crafts Alkylation toward Ordered Nanoporous Polymers

The release of hydrogen halides in Friedel–Crafts alkylation has long been considered as troublesome and detrimental. Here we demonstrate that the released HCl in alkylation is beneficial and highly demanded to remove poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) templates from the phenolic supramolecules for the preparation of ordered nanoporous phenolic polymers as additional treatment for template removal is no longer necessary. Friedel–Crafts alkylation using bifunctional alkylation agent, 1,4-bis(chloromethyl)benzene, leads to the hyper-cross-linking of phenolic polymers, thus generating micropores in the skeleton of the polymers. HCl in situ generated as the byproduct during alkylation facilely extracts the copolymer because of its enhanced diffusion through the micropores. The prepared phenolic polymers exhibit high surface areas and well-ordered porosities in a hexagonal or gyriodal structure. The in situ cavitation by alkylation takes place at much milder conditions and has ...

Cloud point behavior of thermosensitive triblock copolymer L61 in the presence of electrolytes

ABSTRACTHerein the effect of additives on the cloud point of thermosensitive copolymer Poly (ethylene oxide)–Poly (propylene oxide)–Poly (ethylene oxide) (PEO–PPO–PEO, L61) was investigated, including NaCl, NaOH, NaBr, Na2CO3, Na3PO4, Na2SO4, Na2HPO4, ZnSO4, FeSO4 and MnSO4 at different concentrations. It was found that the cloud point of L61 was lowered by adding the electrolytes and decreased linearly with increasing electrolytes concentration. In these systems, the addition of polyvalent anions resulted in a more pronounced salting-out effect than monovalent anions. A depression in the cloud point of L61 in the presence of multivalent electrolytes was observed in a trend of > >Cl−. Meanwhile, the ability of divalent anion lower cloud point evaluated by Gibbs free energy was appropriated, and the order as follows: > > . The capacity of divalent cation to reduce the cloud point followed the order Zn2+>Fe2+>Mn2+.

Thermodynamic properties of aqueous PEO–PPO–PEO micelles of varying hydrophilicity with added cisplatin determined by differential scanning calorimetry

Differential scanning calorimetry was performed on a series of aqueous solutions of polyethylene oxide–polypropylene oxide–polyethylene oxide, PEO–PPO–PEO (L101, P104, P105, and F108), amphiphiles in the low concentration regime (0–2 % mass v−1) to resolve the critical micelle concentrations of the neat polymers. Work was done from 2 to 10 % mass v−1 (in 2 % mass v−1 increments) amphiphilic copolymer concentrations and co-formulated with cisplatin concentrations (0–0.1 % mass v−1 in 0.02 % mass v−1 increments) to resolve any deviation in the enthalpy of micelle formation. Enthalpy–entropy compensation plots for each neat copolymer and each amphiphile solution mixed with cisplatin were obtained. Two types of behaviors were observed: a drug-influenced compensation temperature profile (P104) and a drug-invariant behavior (L101, P05, and F108) where the change in compensation temperature was <1 °C. Only neat P104 was found to be profoundly influenced by the presence of cisplatin that must reorganize the core–shell interface between the hydrophobic and hydrophilic regions of the micelle. Adding cisplatin lowered Tcompensation from 302.1 to 288.8 K for Pluronic P104.

Wetting of Hydrophilic Electrospun Mats Produced by Blending SEBS with PEO–PPO–PEO Copolymers of Different Molecular Weight

The interaction of electrospun mats with water is critical for many possible applications, and the water contact angle on the surface is the parameter usually measured to characterize wetting. Although useful for hydrophobic surfaces, this approach is limited for hydrophilic mats, where wicking also has to be considered. In this case, it is still unclear how the fiber surface chemical composition and morphology will affect the wetting behavior of electrospun mats. In this work, wetting was studied with different hydrophilic membranes produced by blending thermoplastic elastomer poly(styrene)-b-poly(ethylene-butylene)-b-poly(styrene) (SEBS) with amphiphilic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) molecules. Three different types of PEO-PPO-PEO, with different molar masses, PEO content, and physical form were used. The effect of these differences on the wetting behavior of the electrospun mats was evaluated by contact angle goniometry, wicking measurements, and different imaging techniques. X-ray photoelectron spectroscopy was used to characterize the surface chemical composition. The smaller molecules quickly saturated the surface at low concentrations, making the mats hydrophilic. The sheath of PEO-PPO-PEO also resulted in fast absorption of water, when comparing the saturated and nonsaturated surfaces. Longer PEO chain-ends seemed to hinder complete segregation and also led to a higher activation time when in contact with water. Liquid PEO-PPO-PEO was easily leached by water.

Structural Study of Four-Armed Amphiphilic Star-Block Copolymers: Pristine and End-Linked Tetronic T1307.

We present a comparative structural study of 30 wt % aqueous suspensions of two related systems based on 4-arm PEO-PPO type of macromolecules (Tetronic T1307, BASF) with the PPO block near the star center. One system concerns the pristine 4-arm PEO-PPO star block copolymer T1307. The second system is a 1:1 blend consisting of, respectively, tetra-amine (TAT) and tetra-N-hydroxysuccinimide (TNT) terminated T1307. The two systems show common characteristics which are also known from linear PEO-PPO type of copolymers (Pluronic, BASF): at low temperatures the measured structure is dominated by the characteristics of individual molecules, while at higher temperatures hydrophobic effects of the PPO domains cause self-assembly into spherical or rodlike micelles. These micelles form in both systems ordered mesophases. The pristine T1307 copolymer suspension behaves generally very similarly to linear PEO-PPO type of di- and triblock copolymers: unimers at low temperatures associating into micelles at higher temperatures, forming subsequently cubic and hexagonal phases upon further increase in temperatures. The cubic phase of the 30 wt % Tetronic T1307 has FCC symmetry. The structure of the cross-linked 30 wt % 1:1 TAT-TNT system is basically organized into two-dimensional network sheets. At low temperatures the system is rather disordered but still with a sharp correlation peak which is associated with the distance between neighboring network sheets. Upon raising temperatures, PPO self-assembly causes organization across neighboring sheets, resulting in cylinder-like assemblies perpendicular to the sheets. These cylinders form hexagonal structure.

Interaction between bile salt sodium glycodeoxycholate and PEO–PPO–PEO triblock copolymers in aqueous solution

Bile salts can associate to PEO–PPO–PEO block copolymer micelles and disintegrate them depending on the relative block length and molecular weight of the copolymers and bile salt/copolymer molar ratio.

Surface adsorption of triblock copolymer (PEO–PPO–PEO) on cellulose nanocrystals and their melt extrusion with polyethylene

Cellulose nanocrystals (CNC) have gained a lot of interest in recent years in the field of composites due to their unique mechanical properties and also because cellulose is the most abundant and renewable polymer in nature.

Transport of nanoparticulate material in self-assembled block copolymer micelle solutions and crystals.

Water soluble poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) [PEO-PPO-PEO] triblock copolymers self-assemble into thermoreversible micellar crystals comprised of periodically spaced micelles. The micelles have PPO cores surrounded by hydrated PEO coronas and the dimensions of the unit cell of the organized micelles is on the order of several to tens of nanometers. Fluorescence recovery after photobleaching (FRAP) is used to quantify nanoparticle transport in these nanostructured polymer micelle systems. Diffusivity of bovine serum albumin (BSA, Dh ∼ 7 nm) is quantified across a wide range of polymer, or micelle, concentrations covering both the disordered fluid as well as the structured micellar crystal to understand the effects of nanoscale structure on particle transport. Measured particle diffusivity in these micellar systems is reduced by as much as four orders of magnitude when compared to diffusivity in free solution. Diffusivity in the disordered micellar fluid is best understood in terms of diffusion through a polymeric solution, while transport in the structured micellar phase is possibly due to hopping between interstitial sites. These results not only show that the nanoscale structures of the micelles have a measureable impact on particle diffusivity, but also demonstrate the ability to tune nanoscale transport in self-assembled materials.

F-127-PEI co-delivering docetaxel and TFPI-2 plasmid for nasopharyngeal cancer therapy

The co-delivery of drug and gene has become the primary strategy in cancer therapy. However, to construct one safe co-delivering system with higher drug loading and gene transfection efficiency for cancer therapy is still challenging. Herein, a novel degradable nanocarriers were synthesized and characterized in this study, which was composed of polyethylenimine (PEI)-linked PEO–PPO–PEO (Pluronic F127), called F127-PEI. Then the nanocarrier was used for hydrophobic docetaxel (DOC) and functional gene (TFPI-2 plasmid) co-delivery to treat nasopharyngeal cancer (NPC). The results indicated that F127-PEI nanocarriers had higher DOC loading amount and possessed good gene delivery effect in vitro. For co-delivery analysis, the obtained F127-PEI/DOC/TFPI-2 complexes could induce a more significant apoptosis than DOC or TFPI-2 alone, and decreased invasive capacity of NPC HNE-1 cells more obviously. Moreover, the F127-PEI copolymer exhibited better blood compatibility and lower cytotoxicity compared to PEI-25k by the hemolysis and MTT assays, which suggests a promising potential for NPC therapy.

Block length determines the adsorption dynamics mode of triblock copolymers to a hydrophobic surface

Many material processes including surface modification and material fabrication depend on the mechanism by which polymers are adsorbed onto solid/liquid interfaces. Although the morphologies of block copolymers near the interface have been extensively investigated, the understanding of the adsorption dynamics is still limited. Here, we show that the block length determines the dynamic adsorption mode under conditions beyond the critical micelle concentration (CMC). The adsorption kinetics are investigated using in situ experimental characterization combined with Dissipative Particle Dynamics simulations. Two types of symmetrical triblock copolymers, i.e., PEO–PPO–PEO, with different hydrophilic PEO block lengths are studied. While both types of copolymers present similar adsorption dynamics at concentrations below the CMC, their dynamic adsorption modes are distinct at concentrations above the CMC. The present experimental–numerical study provides a mechanistic interpretation of this difference, which casts helpful insight for the dynamic control process of surface modification and material fabrication.