Influence of Grafted Chain Length of a Phenolic Copolymer on Its Complex Formation with Poly(vinyl Pyrrolidone) and Poly(ethylene Oxide)

A phenolic copolymer has been grafted with oligomers of different chain lengths. Polymer-polymer complexation has been studied between graft copolymers and nonionic polymers, such as polyvinyl pyrrolidone) and poly(ethylene oxide), in an acetone-methanol mixture by several methods, e.g., viscosity, conductance, and apparent pH measurements. A distinct stepwise complexation between PVP and graft copolymers has been observed. The length of the side chain also seemed to influence interpolymer complex formation. Some of these observations have been interpreted with reference to the actual structure of the graft copolymers.     

PH effects in the complex formation and blending of poly(acrylic acid) with poly(ethylene oxide)

The effect of pH on the complex formation between poly(acrylic acid) (PAA) and poly(ethylene oxide) (PEO) has been studied in aqueous solutions by turbidimetric and fluorescent methods. It was shown that the formation of insoluble interpolymer complexes is observed below a certain critical pH of complexation (pH(crit1)). The formation of hydrophilic interpolymer associates is possible above pH(crit1) and below a certain pH(crit2). The effects of polymer concentrations in solution and PEO molecular weight as well as inorganic salt addition on these critical pH values were studied. The polymeric films based on blends of PAA and PEO were prepared by casting from aqueous solutions with different pHs. These films were characterized by light transmittance measurements and differential scanning calorimetry. The existence of the pH value above which the polymers form an immiscible blend was demonstrated. The transitions between the interpolymer complex, miscible blend, and immiscible blend caused by pH changes are discussed. The recommendations for preparation of homogeneous miscible films based on compositions of poly(carboxylic acids) and various nonionic water-soluble polymers are presented.     

Investigation and physicochemical characterization of vinpocetine-sulfobutyl ether beta-cyclodextrin binary and ternary complexes

The purpose of this study was to investigate the interactions between vinpocetine (VP), sulfobutyl ether beta-cyclodextrin (SBEbetaCD) and the water-soluble polymers polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC). The water-soluble polymers were shown to improve the complexation efficiency of SBEbetaCD, and thus less SBEbetaCD was needed to prepare solid VP-SBEbetaCD complexes in the presence of the polymers. The interactions between VP and SBEbetaCD, with or without PVP or HPMC, were thoroughly investigated in aqueous solutions using the phase-solubility method as well as in the solid state. The amount of VP solubilized in water or aqueous polymer solution increased linearly with increasing SBEbetaCD concentration, demonstrating A(L)-type plots. We estimated the apparent stability constant (K(c)) at room temperature of VP-SBEbetaCD binary complex to be 340 M(-1) and this value increased to 490 M(-1) or 390 M(-1), respectively, with the addition of PVP and HPMC, assuming a 1 : 1 VP-SBEbetaCD molar ratio. Improvement in the K(c) values for ternary complexes clearly confirmed the benefit of the addition of water-soluble polymers to promote higher complexation efficiency. Solid VP-SBEbetaCD binary and ternary systems were prepared by physical mixing, kneading, coevaporation, and lyophilization methods and fully characterized by scanning electron microscopy, differential scanning calorimetry, and X-ray diffractometry. The results obtained suggest that coevaporation and lyophilization methods yield a higher degree of amorphous entities and indicated formation of VP-SBEbetaCD binary and ternary complexes.     

Structural and transport characteristics of polyethylene oxide/phenolic resin blend solid polymer electrolytes

Details on the structure and transport characteristics of the solid polymer electrolyte polyethylene oxide (PEO)/lithium salt (LiClO₄) modified by novolac phenolic resin are presented here. From IR spectra it could be concluded that complex formation occurred through multiple interactions between the ether oxygen of PEO–lithium, phenolic lithium, and the phenolic ether oxygen of PEO. The free hydroxyl band in phenolic reflected that phenolic closely interacted with both the PEO polymer and ionic salt. With increasing salt content in PEO, the vibration band corresponding to the ClO anion (～623 cm^?1) displayed growth of a shoulder at ～635 cm^?1, suggesting the formation of Li⁺…ClO₄^? ion pairing. However, in the presence of phenolic, ion‐pairing formation was effectively suppressed, which suggested that the phenolic moiety facilitated a greater degree of LiClO₄ salt dissociation. Activation energy analysis revealed two conducting pathways: one through the amorphous PEO and the other through the PEO/phenolic amorphous matrix. The high ion conductivity originated from effective salt dissociation and the establishment of a new conduction network formed by PEO and phenolic. Furthermore, the structural modification also extended the thermal stability and mechanical strength of the solid polymer electrolyte composite. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3866–3875, 2004     

The association of aqueous phenolic resin with polyethylene oxide and poly(acrylamide-co-ethylene glycol)

Comb copolymers formed from acrylamide and poly(ethylene-glycol) methacrylate macro-monomer (PAM-co-PEG) were compared to poly(ethylene oxide) (PEO) with respect to hydrogen bond complex formation with water-borne phenolic resins. The behaviors of the two types of high molecular weight polyethers were similar. Complex formation gave a transient increase in viscosity followed by precipitation. Copolymers with pendant PEG chain lengths ≥ 9 formed complexes with phenolic resin whereas PEG homopolymer with a molecular weight of 2000 did not form a complex. For both copolymer and high molecular weight PEO, the tendency of the complex to precipitate increased when the pH was decreased from 7 to 4. Acridine orange, a cationic dye, bound to the phenolic resin and, after the addition of PEO, yielded visible complex gels with diameters about 20 μm. © 1995 John Wiley & Sons, Inc.     

Preparation of Ultrafine Water-soluble Polymers Nanofiber Mats via Electrospinning

A series of water-soluble polymers such as poly(ethylene oxide)(PEO),polyacrylamide(PAM) and poly(vinyl pyrrilidone)(PVP) was successfully prepared via the electrospinning of their aqueous solutions without the use of a surfactant.The effects of solution properties on the electrospinning of PEO,PAM and PVP solutions were investigated.The viscosity of the solution,charge density carried by the jet,and the surface tension of the solution are the key factors that influence the morphology and diameter size of t...     

Controlled synthesis and association behavior of graft Pluronic in aqueous solutions

Poly(vinyl pyrrolidone) (PVP) was grafted onto Pluronic F127 (PEO-PPO-PEO) to produce novel amphiphilic PVP-g-F127 graft copolymers. A controlled synthesis method was used to graft PVP onto different parts of F127. Two types of graft polymers were obtained: one has PVP grafted onto the PEO part of F127 and the other has PVP grafted onto the PPO part of F127. The association behavior of the two modified polymers was examined using differential scanning calorimetry, surface tension measurements, and dynamic light scattering.     

Modification of poly(methyl methacrylate) microchannels for highly efficient and reproducible electrophoretic separations of double-stranded DNA

This paper deals with dynamic coating of the microchannels fabricated on poly(methyl methacrylate) (PMMA) chips and DNA separation by microchip electrophoresis (MCE). After testing a number of polymers, including 2-hydroxyethyl cellulose, hydroxypropylmethyl cellulose, different sizes of poly(ethylene oxide) (PEO), and poly(vinyl pyrrolidone) (PVP), we found that coating of the PMMA microchannels with PEO(Mr = 6.0 x 10(5) g/mol) on the first layer is essential to minimize the interaction of DNA with PMMA surface. To achieve high efficiency, multilayer coating of PMMA chips with PEO, PVP, and PEO containing gold nanoparticles [PEO(GNP)] is important. A 2-(PEO-PVP)-PEO(GNP) PMMA chip, which was repeatedly coated with 1.0% PEO and 5.0% PVP twice, and then coated with 0.75% PEO(GNP) each for 30 min, provided a high efficiency (up to 1.7 x 10(6) plates/m) for the separation of DNA markers V (pBR 322/HaeIII digest) and VI (pBR 328/BgiI digest and pBR 328/HinfI digest) when using 0.75% PEO(GNP). With such a high efficiency, we demonstrated the separation of hsp65 gene fragments of Mycobacterium HaeIII digests by MCE within 90 s. The advantages of this approach to DNA analysis include ease of filling the microchannel with 0.75% PEO(GNP), rapidity, and reproducibility.     

Nonlinear Effects on the Ionic Conductivity of Polyethylene Oxide)/Uthium Perchlorate Complexes Caused by the Blending of Polyvinyl Acetate)

Poly(ethylene oxide) (PEO)/LiClO₄/poly(vinyl acetate) (PVAc) and PEO/LiClO₄/poly(vinyl pyrrolidone) (PVP) complexes were prepared with various weight ratios of PVAc and PVP to PEO. The conductivity (σ) of the PEO/LiClO₄ complex was increased in a nonlinear fashion by the presence of up to 60 wt% PVAc. PEO/LiClO₄/PVAc complexes with weight percents of PVAc greater than 60 had σ's less than that of PEO/LiClO₄. The σ of PEO/LiClO₄ was decreased by the presence of any PVP.     

New associating polymer systems involving water soluble β-cyclodextrin polymers

Original associating systems have been obtained by mixing hydrophobically end-capped polyethylene oxide and water soluble β-cyclodextrin polymers in aqueous solutions. The hydrophobic ends of the PEO polymers, naphtyl and adamantyl groups, have been chosen in order to match the β-cyclodextrin cavities. Inclusion complex formation between the PEO terminal groups and β-cyclodextrin are at the origin of polymolecular associations. Complexation constants have been determined by fluorescence methods, using a fluorescent probe 1-8 ANS as a competitor for complexation against the adamantyl groups or directly checking the fluorescence of the naphtytl groups by fluorescence anisotropy measurements. The onsets of the polymolecular associations have been monitored by viscosimetry.     

An NMR investigation of the interaction of polyethylene oxide with water‐soluble poly(vinyl phenol‐co‐potassium styrene sulfonate)

The water‐soluble complex of polyethylene oxide (PEO) with poly (vinyl phenol‐co‐potassium styrene sulfonate) (PVPh‐co‐KSS) was studied by liquid‐state NMR. PEO showed two peaks in the ¹H spectra, which corresponded to the free and complexed PEO. The ratio of the free PEO/complexed PEO was decreased with the increase in the mixing ratio of PVPh‐co‐KSS/PEO. Some of the complex formation disappeared when the pH was raised from 6.4 to 12.0. It had been thought that at high pH, the phenolic groups dissociate and thus cannot form hydrogen bonds. The fact that NMR indicates some interaction at pH 12.0 implies there are some other interactions, such as hydrophobic interactions between the aromatic rings and the polyether methylene groups, contributing to PEO and PVPh‐co‐KSS complex formation. Nuclear Overhauser effect (NOE) cross peaks were observed between PEO and the aromatic protons of PVPh‐co‐KSS in nuclear Overhauser effect spectra (NOESY) suggesting that the distance between PEO and the aromatic protons of PVPh‐co‐KSS was less than 5 Å. The exchange between the complexed PEO and the free PEO was slow on the NMR time scale. The ratio of the integral of the complexed PEO to the free PEO increased with temperature, indicating that the number of PEO segments interacting with the aromatic ring increases with temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1276–1284, 2000     

Determination of the complex formation constants for some water-soluble polymers with trivalent metal ions by differential pulse polarography

The formation of metal complexes between water-soluble polymers, poly(vinyl alcohol) [PVA], poly(N-vinylpyrrolidone) [PVP], poly(acrylamide) [PAAm] and poly(ethylene oxide) [PEO] with trivalent metal ions, Fe³⁺, Cr³⁺, and V³⁺ were studied by using differential pulse polarography (DPP). The general experimental observation is the shift of totally reversible reduction peaks (M³⁺+Hg+e^–M²⁺+Hg) towards more negative potentials when the complexing water-soluble polymers are added to the solution of trivalent metal ions. The negative shift in potential permitted the determination of complex formation constants (K_f) between trivalent metal ions and water soluble polymers. The complex formation constants for Fe³⁺, Cr³⁺, and V³⁺ ions with these polymers increased in the order of V³⁺>Cr³⁺>Fe³⁺.     

温敏梳状嵌段共聚物对PS微球阻抗蛋白吸附作用的研究

采用可逆加成断裂链转移聚合(RAFT)方法和大分子单体技术,制备了温敏性聚N-异丙基丙烯酰胺(PNIPAM)-聚乙烯基吡咯烷酮(PVP)与PNIPAM-聚氧化乙烯(PEO)梳状嵌段共聚物,这些共聚物具有PVP或PEO支链.以溶菌酶为蛋白模型研究了所得共聚物对聚苯乙烯(PS)微球表面蛋白吸附的抑制作用.通过絮凝实验、激光散射法表观粒径测定、电泳迁移率测定及蛋白吸附量的定量数据比较了不同梳状结构的抗蛋白吸附效果.结果表明,预吸附梳状嵌段共聚物可有效阻抗蛋白吸附,亲水支链增加阻抗性能提高,即使环境温度高于PNIPAM的相转变温度也能阻抗蛋白吸附.透射电镜和共聚物胶体粒径测试表明,梳状嵌段共聚物阻抗蛋白吸附的机制是预吸附后PVP或PEO亲水支链在微球表面形成了阻隔层.通过PS微球的变温絮凝实验可评价预吸附聚合物的抗蛋白吸附性能,快速获得定性结果.     

Study of copolymer–copolymer interactions and formation of intermacromolecular complexes

Interpolymer complex formation has been studied between methacrylic acid-methacrylamide copolymer and acrylic acid–acrylamide copolymer. The respective co-monomer units of the two copolymers enter into complex formation through H-bonding and ion dipole interactions. The unreacted units in the copolymer complex also interact with homopolymers such as PEO and PVP to form ternary complex. Formation of complexes and replacement reactions could be shown through several experimental techniques, e.g., viscometry, conductometry, and potentiometry.     

Studies on interpolymer self-organisation behaviour of protoporphyrin IX bound poly(carboxylic acid)s with complimentary polymers by means of fluorescence techniques

Covalently bound protoporphyrin IX was used as a fluorophore to investigate the interpolymer complex formation between the poly(carboxylic acid)s, PMAA/PAA and poly(N-vinyl pyrrolidone), PVP, poly(ethylene oxide), PEO or poly(ethylene glycol), PEG. Absorption and emission spectral properties of protoporphyrin IX bound to PAA, PMAA and PVP have been studied. Protoporphyrin IX in poly(MAA-co-PPIX) was found to be present in the dimer or higher aggregated form at low pH due to the environmental restriction imposed by the polymer whereas in the case of poly(AA-co-PPIX) and poly(VP-co-PPIX), PPIX exists in monomeric form. The fluorescence intensity and lifetime of PPIX bound to poly(carboxylic acid)s increase on complexation through hydrogen bonding with PVP, PEO and PEG due to the displacement of water molecules in the vicinity of the PPIX. Poly(MAA-co-PPIX) shows longer fluorescence lifetime due to the more compact interpolymer complexation as compared to poly(AA-co-PPIX) due to the enhanced hydrophobicity of PMAA. Poly(VP-co-PPIX) shows a decrease in the fluorescence lifetime on complexation with PMAA or PAA due to the hydrophilic and microgel like environment of the fluorophore bound to PVP. The contrasting behaviour of the same polymer adduct with respect to the site of the fluorophore is interpreted to be due to the solvent structure which determines the environment of the fluorophore.     

The influence of PEO/poly(vinyl phenol-co-styrene sulfonate) aqueous complex structure on flocculation

Colloidal suspensions were flocculated with complexes formed from high molecular weight polyethylene oxide (PEO) and a cofactor. Poly(vinyl phenol-co-potassium styrene sulfate) (PKS) or poly(styrene-co-styrene sulfonate) (PS-co-SSS) copolymers were used as the cofactors for this work. The larger the PEO/cofactor complex species, the better the initial flocculation. Factors such as increasing temperature or ionic strength that gave smaller complexes also gave poorer flocculation. Cofactor performance was sensitive to the balance of hydrophobic phenolic groups and hydrophilic styrene sulfonates. If there are too few phenolic groups, the PEO/PSK complexes are large but are too weak to give shear-resistant flocs, whereas complexes formed with high phenolic content PSK are relatively small, giving poorer flocculation but more shear-resistant flocs. Both phenyl and phenol groups are effective as the hydrophobic component in the cofactor. The hydrogen-bonding potential of phenolic cofactors does not seem to offer much advantage relative to phenyl groups. A crucial step in the flocculation is the adsorption of PEO/cofactor complex onto the target colloids. Thus, flocculation is sensitive to the target colloid surface chemistry. Positively charged precipitated calcium carbonate and surfactant-free polystyrene latex are particularly easy to flocculate because adsorption is driven by electrostatic and hydrophobic interactions, respectively. By contrast, the latex coated with hydrophilic poly(N-isopropylacrylamide) (PNIPAM) does not flocculate because the PEO/cofactor complex does not bind to PNIPAM. Finally, the flocculation of highly negatively charged, dextran sulfate coated calcium carbonate seems to be stimulated by the presence of soluble calcium ions that make the complex less soluble and more likely to adsorb.     

PEO／PVP共混体系结晶行为

本文用WAXD、PLM、DSC方法研究了聚氧化乙烯(PEO)/聚乙烯基吡咯烷酮(PVP)共混体系的结晶行为,探索了两组分聚合物间相互作用及体系结晶度与非晶组分含量的关系。DSC研究表明PEO/PVP共混体系具有两个玻璃化转变温度,分别是纯组分的T_g,无相容性。应用Avrami和LH方程对其动力学参数进行了研究。偏光显微镜观察了共混物结构形态。     

Polymer-colloid complexes in three-component system: poly(styrene-alt-maleic acid)-poly(ethylene oxide)-silica sol in aqueous medium

Complex formation in the model three-component system, including polymer-polymer complex of poly(styrene-alt-maleic acid) (PSMA) and poly(ethylene oxide) (PEO), and also silica sol (SiO₂) in aqueous solution as a function of molecular weight of PEO and the order of component mixing, were investigated. The degree of binding of PSMA links with PEO and SiO₂ as well as the Gibbs energy of formation of the polymer-polymer complex and polymer-colloid complexes were defined. It was shown that the main factor of stabilization of the structure is hydrogen bonds. The conditions of three-component polymer-colloid system are practically independent of the order of component mixing. The spontaneous formation of polymer-colloid complexes between chemically complementary polymers and small dispersed particles is considered as the main reason for the abnormally high binding ability of colloid particles to the polymer-polymer complex.     

固体NMR研究PAA/PEO共混物中氢键相互作用与结构演化

分子间相互作用是决定材料结构和性能的关键因素之一,而如何在分子水上实现对复杂相互作用分子的检测仍然是一个挑战性课题。本工作首先在不同p H值条下以聚丙烯酸/聚环氧乙烷(PAA/PEO)的混合水溶液制备了系列的固体薄膜,然后采用多种基于连续相调制多脉冲技术的一维和二维~1H多脉冲去耦(CRAMPS)固体NMR新技术,并结合高分辨~(13)C交叉极化魔角旋转(CPMAS)、~(23)Na多量子(MQ)等多核固体NMR实验,对PAA/PEO聚合物共混物的微观结构和动力学进行了原位和系统的研究。通过不同类型的~1H高分辨CRAMPS实验检测到共混物中包含多种不同类型质子:通过氢键相互作用形成二聚体的COOH基团、自由COOH基团、与水结合的COOH基团和主链基团。随着p H值的升高,除主链质子外,大部分其它区域的信号都明显降低,这是由于PAA与PEO以及水的氢键作用减弱所致。这些CRAMPS NMR技术也被用来阐明不同p H值制备的样品中不同基团的分子运动性。此外,二维~1H-~1H自旋交换NMR实验提供了关于聚合物PAA与PEO大分子链间、以及水与聚合物的相互作用。~1H自旋扩散实验表明,在这些共混物中明显存在相微观相分离的结构,并且测定的分散相区尺寸约为17 nm。~(23)Na MQMAS实验揭示了在共混物中存在两种类型~(23)Na位,一种是自由的钠离子,另一种是与大分子相互作用的Na离子。特别是通过~1H-检测的~(23)Na-~1H CPMAS实验揭示了Na~+离子的位置远离PEO而与PAA临近。上述这些SSNMR实验结果在分子水平上提供了氢键相互作用对PAA/PEO共混物微观结构和动力学影响的详细信息,可以获得不同p H值对PAA与PEO的氢键作用、相容性、微观结构、水-聚合物相互作用和不同组分分子运动性的影响。在上述核磁共振研究的基础上,我们提出了一种新的PAA/PEO共混物的结构模型,该模型首次成功地揭示了不同的p H值对PAA/PEO共混物中微观结构和动力学的影响。本工作清楚地表明,固态核磁共振是在分子水平上研究具有复杂相互作用的多相聚合物材料的有力工具。本文的研究工作对于探索检测聚合物弱相互作用的新方法和发展基于氢键相互作用的聚合物新材料的开发具有重要意义。     

Fractionation and characterization of phenolic resins by high-performance liquid chromatography and gel-permeation chromatography combined with ultraviolet, refractive index, mass spectrometry and light-scattering detection

HPLC and gel permeation chromatographic (GPC) characterization of complex phenol-formaldehyde resins is described. Reversed-phase HPLC fingerprints the phenolic monomers, dimers and some oligomers. The molecular masses of these phenolic compounds were determined using an ion trap mass spectrometer. GPC analyzes tetrahydrofuran-soluble phenolic polymers beyond HPLC capability. The molecular mass distribution and structural information of the phenolics was determined by both conventional and laser light-scattering calibration methods. GPC with both UV and refractive index detection provides weight concentration of phenolic resin and the molar concentration of the phenol unit in the oligomers or polymers.