Synthesis and characterization of amphiphilic PMTFPS‐b‐PEO diblock copolymers

A series of new amphiphilic poly[methyl(3,3,3‐trifluoropropyl) siloxane]‐b‐poly(ethyleneoxide) (PMTFPS‐b‐PEO) diblock copolymers with different ratio of hydrophobic segment to hydrophilic segment were prepared by coupling reactions of end‐functional PMTFPS and PEO homopolymers. PMTFPS‐b‐PEO diblock copolymers synthesized were shown to be well defined and narrow molecular weight distributed by characterizations such as NMR, GPC, and FTIR. Additionally, the solution properties of these diblock copolymers were investigated using tensiometry and transmission electron microscopy. Interestingly, the critical micellization concentration increases with increasing length of hydrophobic chain. Transmission electron microscopy studies showed that PMTFPS‐b‐PEO diblock copolymers in water preferentially aggregated into vesicles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of graft copolymer polyethylene‐ graft‐poly(ethylene oxide) by a new anionic graft‐from polymerization

A series of amphiphilic graft copolymers, PE‐graft‐PEO, containing hydrophobic polyethylene (PE) as the backbone and hydrophilic poly(ethylene oxide) (PEO) as the side‐chain, have been synthesized by a novel route. The graft structure and the molecular weight, as well as the molecular weight distribution of the graft copolymer can easily be controlled. The molecular weight of the side‐chain PEO is proportional to the reaction time and the monomer concentration, which indicates the ‘living’ character of the anionic polymerization of ethylene oxide. The produced copolymers PE‐graft‐PEO were characterized by ¹H NMR and DSC measurements. Copyright © 2004 Society of Chemical Industry     

Crystallization behavior of “wet brush” and “dry brush” blends of PS‐b‐PEO‐b‐PS/h‐PEO

The crystallization behavior of the blending system consists of homopolymer poly(ethylene oxide) (h‐PEO) with different molecular weights, and polystyrene‐block‐poly (ethylene oxide)‐block‐polystyrene (PS‐b‐PEO‐b‐PS) triblock copolymer has been investigated by DSC measurements. The crystallization of PEO block (b‐PEO) in block copolymer occurs under much lower temperature than that of the h‐PEO in the bulk (ΔT > 65 °C), which is attributed to the homogeneous nucleation crystallization behavior of the b‐PEO microdomains. In both the “dry‐brush” and the “wet brush” blending systems, the homogeneous nucleation crystallization temperature of PS‐b‐PEO‐b‐PS/h‐PEO blends increases due to the increase of the domain size. The heterogeneous nucleation crystallization temperatures of h‐PEO in the wet brush blending systems are higher than that of the corresponding h‐PEO in the bulk. At the same time, the heterogeneous nucleation crystallization temperature of b‐PEO10000 decreases from 43°C to 30°C and 40°C in the h‐PEO600 and h‐PEO2000 blending systems, respectively, because of the stretching of the PEO chains in the wet brush. However, this kind of phenomenon does not happen in the dry brush blending systems. The self‐seeding procedure was used to further ascertain the nucleation mechanism in the crystallization process. As a result, the self‐seeding domains have been confirmed, and the difference between the dry brush and wet brush systems has been observed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Property enhancement in polypropylene ternary blend nanocomposites via a novel poly(ethylene oxide)‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene toughener–compatibilizer system

Synthesis and characterization of a novel toughener–compatibilizer for polypropylene (PP)–montmorillonite (MMT) nanocomposites were conducted to provide enhanced mechanical and thermal properties. Poly(ethylene oxide) (PEO) blocks were synthetically grafted onto maleic anhydride‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene (SEBS‐g‐MA). Special attention was paid to emphasize the effect of PEO‐grafted SEBS (SEBS‐g‐PEO) against SEBS‐g‐MA on morphology, static/dynamic mechanical properties and surface hydrophilicity of the resultant blends and nanocomposites. It was found that the silicate layers of neat MMT are well separated by PEO chains chemically bonded to nonpolar SEBS polymer without needing any organophilic modification of the clay as confirmed by X‐ray diffraction and transmission electron microscopy analyses. From scanning electron microscopy analyses, elastomeric domains interacting with MMT layers via PEO sites were found to be distributed in the PP matrix with higher number and smaller sizes than the corresponding blend. As a benefit of PEO grafting, SEBS‐g‐PEO‐containing nanocomposite exhibited not only higher toughness/impact strength but also increased creep recovery, as compared to corresponding SEBS‐g‐MA‐containing nanocomposite and neat PP. The damping parameter of the same nanocomposite was also found to be high in a broad range of temperatures as another advantage of the SEBS‐g‐PEO toughener–compatibilizer. The water contact angles of the blends and nanocomposites were found to be lower than that of neat hydrophobic PP which is desirable for finishing processes such as dyeing and coating. © 2018 Society of Chemical Industry     

Synthesis of poly(fluorinated styrene)‐block‐poly(ethylene oxide) amphiphilic copolymers via atom transfer radical polymerization: potential application as paper coating materials

BACKGROUND: The surface of a substrate which comprises a fibrous material is brought into contact with a type of amphiphilic block copolymer which comprises hydrophilic/hydrophobic polymeric blocks. These amphiphilic copolymers have been synthesized by atom transfer radical polymerization (ATRP) technique. The atom transfer radical polymerization of poly(2,3,4,5,6‐pentafluorostyrene)‐block‐poly(ethylene oxide) (PFS‐b‐PEO) copolymers (di‐ and triblock structures) with various ranges of PEO molecular weights was initiated by a PEO chloro‐telechelic macroinitiator. The polymerization, carried out in bulk and catalysed by copper(I) chloride in the presence of 2,2′‐bipyridine ligand, led to A–B–A amphiphilic triblock and A–B amphiphilic diblock structures. RESULTS: With most of the macroinitiators, the living nature of the polymerizations led to block copolymers with narrow molecular weight distributions (1.09 < M_w/M_n < 1.33) and well‐controlled molecular structures. These block copolymers turned out to be water‐soluble through adjustment of the PEO block content (>90 wt%). Of all the block copolymers synthesized, PFS‐b‐PEO(10k)‐b‐PFS containing 10 wt% PFS was found to retard water absorption considerably. CONCLUSION: The printability of paper treated with the copolymers was evaluated with contact angle measurements and felt pen tests. The adsorption of such copolymers at the solid/liquid interface is relevant to the wetting and spreading of liquids on hydrophobic/hydrophilic surfaces. Copyright © 2009 Society of Chemical Industry     

Dual pH‐ and thermal‐responsive nanocomposite hydrogels for controllable delivery of hydrophobic drug baicalein

Hydrogels have been widely used as mild biomaterials due to their bio‐affinity, high drug loading capability and controllable release profiles. However, hydrogel‐based carriers are greatly limited for the delivery of hydrophobic payloads due to the lack of hydrophobic binding sites. Herein, nano‐liposome micelles were embedded in semi‐interpenetrating poly[(N‐isopropylacrylamide)‐co‐chitosan] (PNIPAAm‐co‐CS) and poly[(N‐isopropylacrylamide)‐co‐(sodium alginate)] (PNIPAAm‐co‐SA) hydrogels which were responsive to both temperature and pH, thereby establishing tunable nanocomposite hydrogel delivery systems. Nano‐micelles formed via the self‐assembly of phospholipid could serve as the link between hydrophobic drug and hydrophilic hydrogel due to their special amphiphilic structure. The results of transmission and scanning electron microscopies and infrared spectroscopy showed that the porous hydrogels were successfully fabricated and the liposomes encapsulated with baicalein could be well contained in the network. In addition, the experimental results of response release in vitro revealed that the smart hydrogels showed different degree of sensitiveness under different pH and temperature stimuli. The results of the study demonstrate that combining PNIPAAm‐co‐SA and PNIPAAm‐co‐CS hydrogels with liposomes encapsulated with hydrophobic drugs is a feasible method for hydrophobic drug delivery and have potential application prospects in the medical field. © 2018 Society of Chemical Industry     

Mechanical properties–morphology relationships in nano‐/microstructured epoxy matrices modified with PEO–PPO–PEO block copolymers

Epoxy‐based blends containing poly(ethylene oxide)‐co‐poly(propylene oxide)‐co‐poly(ethylene oxide) (PEO–PPO–PEO) block copolymers with different PEO/PPO molar ratios have been investigated in order to analyze the effect of the generated morphologies and interactions between components on the mechanical properties of the blends. Mechanical, morphological and dynamic mechanical analyses indicate that the observed increase of flexural modulus can be related to the decrease of free volume. In modified systems that remain miscible, an increase of flexural modulus, strength and fracture toughness can be observed. Also, macrophase‐ and microphase‐separated systems show an increase of fracture toughness but not of flexural modulus and strength at low contents of block copolymers. Copyright © 2007 Society of Chemical Industry     

Synthesis and association properties in water solution of random copolymers of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid and isodecyl methacrylate—potential application as surfactants in micellar‐enhanced ultrafiltration processes

Hydrophobically modified water‐soluble polymers have been prepared by copolymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) and isodecyl methacrylate (iDMA) in N,N‐dimethylformamide under nitrogen atmosphere, varying the composition feed. Fluorescence spectroscopy was used to further confirm the copolymers self‐aggregate in water. Critical concentration of the self‐aggregate formation (CAC) decreased by increasing the molar fraction of iDMA in the AMPS_co copolymers and varied between 1.20 and 0.04 g/L depending on the degree of hydrophobic modification. Hence, copolymer composition and charge density allowed tuning the pseudomicellar characteristics of these new amphiphilic copolymers. The addition of a salt or a low‐molecular‐weight surfactant was studied. Binding of CTAB to the AMPS_co copolymers leads to a high decrease of CAC, i.e., 0.006 g/L. Effect of the composition in the viscosimetric behavior of the hydrophobically modified copolymers AMPS_co was investigated. The removal of single metal ions, Cu²⁺, and m‐cresol from aqueous solutions by ultrafiltration with the help of the copolymers was investigated. Equilibrium dialysis experiments demonstrate that the formation of hydrophobic microdomains can be used to control the sequestration of foulants, and thus these novel copolymers have potential application as polymeric surfactants in micellar‐enhanced ultrafiltration processes for water purification. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Novel gas sensor from polymer‐grafted carbon black: Vapor response of electric resistance of conducting composites prepared from poly(ethylene‐block‐ethylene oxide)‐grafted carbon black

A crystalline block copolymer of poly(ethylene‐block‐ethylene oxide) (PE‐b‐PEO) was successfully grafted onto a carbon black surface by direct condensation of its terminal hydroxyl groups with carboxyl groups on the surface using N,N′‐dicyclohexylcarbodiimide as a condensing agent. The electric resistance of the composite from PE‐b‐PEO (PEO content is above 50 wt %)‐grafted carbon black drastically increased to 10⁴–10⁶ times of the initial resistance in a vapor of dichloromethane, chloroform, tetrahydrofuran, and carbon tetrachloride, which are good solvents for PE‐b‐PEO, and returned immediately to the initial resistance when the composite was transferred in dry air. However, the change of the electric resistance of these composites was less than one‐tenth in a poor solvent vapor at the same condition. The response of the electric resistance was reproducible and stable even after exposure to a good solvent vapor and dry air with 30 cycles or exposure to the vapor over 24 h. The effect of PEO content on the vapor response was also investigated. The composite from PE‐b‐PEO‐grafted carbon black responded to the low vapor concentration with a linear relationship between the electric resistance and the concentration of the vapor in dry air. This indicates that the composite can be applied as a novel gas sensor. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2437–2447, 2000     

Influence of PS‐b‐PEO diblock copolymers on the compatibility of syndiotactic polystyrene modified epoxy blends

Homogeneous solutions of syndiotactic polystyrene (sPS) in diglycidylether of bisphenol A (DGEBA), containing 2.5, 5 and 7.5 wt % of thermoplastic with or without 0.5 and 1 wt % of poly(styrene‐b‐ethylene oxide) (PS‐b‐PEO) block copolymer, were polymerized using a stoichiometric amount of an aromatic amine hardener, 4,4′‐methylene bis (3‐chloro‐2,6‐diethylaniline) (MCDEA). The dynamic‐mechanical properties and morphological changes of sPS‐(DGEBA/MCDEA) compatibilized with different amount of PS‐b‐PEO have been investigated in this paper. The addition of the block copolymer produced significant changes in the morphologies generated. The size of the dispersed spherical sPS spherulites does not change significantly, but less spherulites of sPS appeared upon network formation in the systems with compatibilizer, what means that addition of compatibilizer in this system delayed crystallization of sPS in sPS‐(DGEBA/MCDEA) systems and change phase separation mechanism from crystallization‐induced phase separation (CIPS) and reaction‐induced phase separation (RIPS) almost only to RIPS. Moreover, PS‐b‐PEO with higher molecular weight of PS block seems to be a more effective compatibilizer than one with lower molecular weight of PS block. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 479–488, 2006     

Crystallization behavior of PEO in blends of poly(ethylene oxide)/poly(2‐vinyl pyridine)‐b‐(ethylene oxide) block copolymer

The crystallization behavior of two molecular weight poly(ethylene oxide)s (PEO) and their blends with the block copolymer poly(2‐vinyl pyridine)‐b‐poly(ethylene oxide) (P2VP‐b‐PEO) was investigated by polarized optical microscopy, thermogravimetric analysis, differential scanning calorimetry, and atomic force microscopy (AFM). A sharp decreasing of the spherulite growth rate was observed with the increasing of the copolymer content in the blend. The addition of P2VP‐b‐PEO to PEO increases the degradation temperature becoming the thermal stability of the blend very similar to that of the block copolymer P2VP‐b‐PEO. Glass transition temperatures, T_g, for PEO/P2VP‐b‐PEO blends were intermediate between those of the pure components and the value increased as the content of PEO homopolymer decreased in the blend. AFM images showed spherulites with lamellar crystal morphology for the homopolymer PEO. Lamellar crystal morphology with sheaf‐like lamellar arrangement was observed for 80 wt% PEO(200M) and a lamellar crystal morphology with grain aggregation was observed for 50 and 20 wt% blends. The isothermal crystallization kinetics of PEO was progressively retarded as the copolymer content in the blend increased, since the copolymer hinders the molecular mobility in the miscible amorphous phase. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Synthesis,self‐assembly,and drug release behavior of star‐shaped poly(ε‐caprolactone)‐b‐poly(ethylene oxide) block copolymer with porphyrin core

A serial of star‐shaped poly(ε‐caprolactone)‐b‐poly(ethylene oxide) (SPPCL‐b‐PEO) block copolymers with porphyrin core were successfully synthesized from ring‐opening polymerization (ROP) of ε‐caprolactone (CL) initiated with porphyrin core, followed by coupling reaction with a hydrophilic polymer poly(ethylene oxide) (PEO) shell. The structure of this novel copolymer were synthesized and thoroughly characterized by Nuclear Magnetic Resonance (NMR), Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR). Notably, the as‐prepared porphyrin‐cored star‐shaped copolymer could self‐assembly into different structures determined by transmission electron microscopy (TEM) and dynamic lighting scattering (DLS), which provides the great potential of using this well‐defined photodynamic therapy material for drug delivery system. Particularly, the doxorubicin‐loaded SPPCL‐b‐PEO nanosphere exhibits property of pH‐induced drug release. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40996.     

Synthesis,photo‐, and electroluminescent properties of the soluble poly[(2,5‐diphenylene‐1,3,4‐oxadiazole)‐ 4,4′‐vinylene]

A novel soluble conjugated polymer, poly[(2,5‐diphenylene‐1,3,4‐oxadiazole)‐4,4′‐vinylene] (O‐PPV), containing an electron‐transporting group on the main chain of PPV, was synthesized according to HORNER mechanism. The oligo‐polymer with M_w = 1000 and T_d = 270°C is soluble in chloroform and tetrahydrofuran. The photoluminescent (PL) properties were investigated using different concentrations of solid‐state O‐PPV/PEO blends absorption and selective excitation measurements. The results show that PL arises from interchain charge‐transfer states in solid‐state O‐PPV. Compared with the analogous single‐layer device constructed with PPV (ITO/PPV/Al), which emits two peaks at λ = 520 nm and 550 nm (shoulder), the electroluminescence (EL) spectrum of the device [ITO/O‐PPV (80 nm)/Al] is a broad peak at λ_max = 509 nm. The quantum efficiency (0.13%) of the device ITO/O‐PPV/Al is much higher than that of the device ITO/PPV/Al, due to the introduction of the electron‐transporting group–oxadiazole units in the main chain of PPV. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3535–3540, 1999     

Aggregation phenomena of amphiphilic UVB absorptive oligoesters containing p‐alkoxycinnamate and poly(ethylene oxide) blocks

The synthesis of new amphiphilic oligoesters containing a hydrophobic block based on p‐alkoxycinnamate and hydrophilic poly(ethylene oxide) is reported. Two hydrophobic monomers, 1,2‐(bis(4‐(2‐carboxyvinyl)phenoxy))ethane ( M2 ) and 1,12‐(bis(4‐(2‐carboxyvinyl) phenoxy))dodecane ( M12 ), were synthesized. Four oligoesters, poly((1,2‐(bis(4‐(2‐carboxyvinyl)phenoxy))ethane) ‐co‐(poly(ethylene oxide)200)) ( P2‐200 ), poly((1,2‐(bis(4‐(2‐carboxyvinyl)phenoxy))ethane)‐co‐(poly(ethylene oxide) 400)) ( P2‐400 ), poly((1,12‐(bis(4‐(2‐carboxyvinyl)phenoxy)) dodecane)‐co‐(poly(ethylene oxide)400)) ( P12‐400 ), and poly((1,12‐(bis(4‐(2‐carboxyvinyl)phenoxy))dodecane)‐co‐ (poly(ethylene oxide)1000)) ( P12‐1000 ) were then constructed by reacting the M2 or M12 with poly(ethylene oxide) (PEO) with lengths of ～ 4 (PEO 200), ～ 10 (PEO 400), or ～ 23 (PEO1000) units using multiple esterifications. These oligoesters possess UVB absorption properties and show good solubility in various organic solvents. Self‐assembly of the oligoesters into aqueous spherical colloids could be induced through an acetone to water solvent displacement technique. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly(ethylene oxide)‐block‐polystyrene copolymers obtained by radical polymerization involving chain‐transfer processes

Poly(ethylene oxide)‐block‐polystyrene (PEO–PSt) block copolymers were prepared by radical polymerization of styrene in the presence of iodoacetate—terminated PEO (PEO‐I) as a macromolecular chain‐transfer agent. PEO‐I was synthesized by successively converting the OH end‐group of α‐methoxy ω‐hydroxy PEO to chloroacetate and then to the iodoacetate. The chain‐transfer constant of PEO‐I was estimated from the rate of consumption of the transfer agent versus the rate of consumption of the monomer (C_{tr, PEO‐I} = 0.23). Due to the involvement of degenerative transfer, styrene polymerization in the presence of PEO‐I displayed some of the characteristics of a controlled/‘living’ process, namely an increase in the molecular weight and decrease of polydispersity with monomer conversion. However, because of the slow consumption of PEO‐I due to its low chain‐transfer constant, this process was not a fully controlled one, as indicated by the polydispersity being higher than in a controlled polymerization process (1.65 versus < 1.5). The formation of PEO–PSt block copolymers was confirmed by the use of size‐exclusion chromatography and ¹H NMR spectroscopy. Copyright © 2004 Society of Chemical Industry     

Carbon nanotube‐hybridized supramolecular hydrogel based on PEO‐b‐PPO‐b‐PEO/α‐cyclodextrin as a potential biomaterial

In virtue of the potential biomedical application of carbon nanotube (CNT), the CNT was hybridized into a supramolecular hydrogel based on the selective inclusion of α‐cyclodextrin (α‐CD) onto poly(ethylene oxide) (PEO) segments of a triblock copolymer, i.e., PEO‐block‐poly(propylene oxide)‐block‐PEO. Different from the previous report, the content of α‐CD, in contrast to that of ethylene oxide unit, was decreased to decrease the network density in hydrogel and hence improve the diffusion of encapsulated substances. As a result, the modulus of the hydrogels climbed slightly after introducing CNT. Furthermore, as the essential properties for wound dressing, the antimicrobial activity, the skin‐adhesion, and water‐retention of such supramolecular hybrid hydrogels were also verified. On the other hand, the supramolecular hybrid hydrogels inherited the shear‐thinning property and are suitable as an injectable biomaterial. The cell viability assay confirmed the equivalent cytotoxicity of the supramolecular hybrid hydrogels to that of the native hydrogels without CNT. Consequently, such CNT‐hybridized supramolecular hydrogel shows a great potential in the biomedical application. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Miscibility and Physical Properties of Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/Poly(ethylene oxide) Binary Blends

In order to improve some inferior physical properties of bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) [P(3HB‐co‐3HHx)] by blending with PEO, the miscibility, spherulite morphology, crystallization behavior and mechanical properties of P(3HB‐co‐3HHx)/PEO binary biodegradable polymer blends were investigated. A good miscibility between P(3HB‐co‐3HHx) with a 3HHx unit content of 11 mol‐% and PEO in the amorphous state was found when the PEO weight fraction was 10 wt.‐%, while the miscibility decreased dramatically when the PEO weight fraction exceeded 20 wt.‐%. Strongly depending on the blend composition, the mechanical properties of P(3HB‐co‐3HHx) was found to be significantly improved by blending with PEO with a weight fraction of ≈5–17.5 wt.‐%.

     

Thermal and mechanical properties of nanocomposites based on a PLLA‐b‐PEO‐b‐PLLA triblock copolymer and nanohydroxyapatite

Composites which combine biocompatible polymers and hydroxyapatite are unique materials with regards to their mechanical properties and bioactivity in the development of temporary bone‐fixation devices. Nanocomposites based on a biocompatible and amphiphilic triblock copolymer of poly(l‐ lactide) (PLLA) and poly(ethylene oxide) (PEO) —PLLA‐b‐PEO‐b‐PLLA— and neat (nHAp) or PEO‐modified (nHAp@PEO) hydroxyapatite nanoparticles were prepared by dispersion in benzene solutions, followed by freeze‐drying and injection moulding processes. The morphology of the copolymers of a PEO block dispersed throughout a PLLA matrix was not changed with addition of the nanofillers. The nHAp particles were spherical and, after modification, the nHAp@PEO nanoparticles were partially agglomerated. In the nanocomposites, these particles characteristics remained unchanged, and the nHAp particles and nHAp@PEO agglomerates were uniformly dispersed through the copolymer matrix. These particles acted as nucleating agents, with nHAp@PEO being more efficient. The incorporation of nHAp increased both the reduced elastic modulus (～22%) and the indentation hardness (～15%) in comparison to the copolymer matrix, as determined by nanoindentation tests, while nHAp@PEO addition resulted in lower increments of these mechanical parameters. The incorporation of untreated nHAp was, therefore, more beneficial with regards to the mechanical properties, since the amphiphilic PLLA‐b‐PEO‐b‐PLLA matrix was already efficient for nHAp nanoparticles dispersion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44187.     

The preparation and characterization of high‐performance and thermally stable electroluminescent poly(p‐phenylene‐vinylene‐b‐oligoethylene oxide)

Two luminescent block copolymers (PPVPEO₂₀₀ and PPVPEO₆₀₀), composed of poly(p‐phenylene‐vinylene) (PPV) segments with three phenylene vinylene units and poly(ethylene oxide) (PEO) segments with molecular weight of 200 and 600, respectively, have been successfully synthesized. The structures of the copolymers were verified using FTIR, ¹H‐NMR, and elemental analysis. Single‐layer polymer light‐emitting electrochemical cells (LEC) devices fabricated on the bases of thin films of PPVPEO₆₀₀ and on the bases of thin films of blends of PPVPEO₂₀₀ with additional PEO both demonstrated good electroluminescent (EL) performance with the onset voltage of 2.6 V and EL efficiency of 0.64 cd/A and 0.68 cd/A at 3.2 V, respectively. Thermal analysis shows that the decomposition temperature of PPVPEO₆₀₀ is about 305°C, which is higher than that of PPVPEO₂₀₀ and PEO. AFM studies of PPVPEO₆₀₀ thin films exhibits that the block copolymer self‐assembles to form nanoscale network structures with pseudo‐cross‐linking points, thus accounting for its high thermal stability and good EL performance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1118–1125, 2007     

Surface structures of solvent‐cast films prepared from poly(ethylene oxide)‐segmented nylons

The surface structures of three kinds of poly(ethylene oxide)‐segmented nylon (PEO‐Ny) films prepared by the solvent‐cast method were investigated with electron spectroscopy for chemical analysis (ESCA). The PEO‐Ny's used were high‐crystalline PEO‐segmented poly(iminosebacoyliminohexamethylene), low‐crystalline PEO‐segmented poly(iminosebacoylimino‐m‐xylene), and amorphous PEO‐segmented poly(iminoisophthaloyliminomethylene‐1,3‐cyclohexylenemethylene), and the PEO contents in the bulk polymers were approximately 10 wt %. The ESCA results showed that the PEO segment was enriched on the top surfaces of all the films, and the degrees of enrichment were different. The mechanism of the PEO enrichment was examined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 10–16, 2002