Size Exclusion Chromatography of Poly(vinylpyrrolidone)

Abstract

Poly(vinylpyrrolidone) and poly(ethylene oxide) separate by hydrodynamic volume on Toyo Soda TSK-PW columns in a mixed solvent mobile phase of 50:50 (v/v) MeOH/H₂O containing 0.1M LiNO₃. From this separation a single universal calibration curve based on hydrodynamic volume [η]M can be obtained. Accurate weight average molecular weights of PVP were obtained by both SEC/LALLS and universal calibration showing good agreement between the two methods. SEC/LALLS overestimates the number average molecular weight for broad distribution polymers due largely to the lack of sensitivity of the LALLS detector to the low molecular weight portion of the polymers, while the universal calibration method slightly underestimates the number average molecular weight as compared to osmometric values.     

超细纳米Pd粒子与聚乙烯吡咯烷酮的相互作用

在微量聚乙烯吡咯烷酮(PVP)存在下, 利用超声还原氯化钯水溶液, 制备出超细纳米Pd颗粒, 用高分辨透射电镜、红外光谱、紫外-可见光谱和X射线光电子能谱等技术对其表面形貌及结构进行了表征. 结果表明, 纳米Pd粒子的粒径均一, 大约为3 nm. 纳米Pd/PVP复合粉末的羰基红外吸收峰比PVP的羰基吸收峰红移9 cm^-1; 且当超声反应50 min时, PVP紫外吸收波峰蓝移16 nm, 表明了纳米Pd与PVP之间存在一定的相互作用力. XPS结果证明, 纳米Pd与PVP的羰基基团通过配位作用使超细纳米Pd粒子得以稳定分散存在.     

Surface Dynamic Elasticity of Poly(ethylene oxide) Monolayers on a Water Surface

The methods of transverse and longitudinal surface waves and of oscillating barrier were used to measure a surface dynamic elasticity of poly(ethylene oxide) films spread on aqueous substrate within the frequency range of 0.001–520 Hz. Unlike the adsorption films, the main relaxation processes in the spread poly(ethylene oxide) films are observed at higher frequencies. A comparison of static and dynamic values of the surface elasticity shows that the surface film at surface polymer concentrations higher than 0.4 mg/m² cannot be considered already as purely two-dimensional film. It was found that the surface tension (surface pressure) can be insufficiently sensitive to conformational transformations in the surface polymer films.     

Rheological Properties of Hydrophobically Modified Poly(acrylic acid) in Mixed Solutions

Hydrophobically modified poly(acrylic acid) (HMPA) with single-tailed pendant side groups was prepared by precipitation polymerization. The effects of polymer concentration, surfactant and co-solvent on the solution properties of HMPA were investigated. HMPA solutions showed good viscosity enhancement and typical shear thinning behavior with increasing concentration. The surfactant TX-10 and co-solvent ethylene glycol gave rise to factors that changed the hydrophobic interactions and in turn the rheology behavior of the solutions. The transient associative network of HMPA in ethylene glycol + water mixed solutions was retained as the temperature was decreased to below 0 °C.     

SIS/石油树脂共混体系的阻尼性质

通过动态力学性能分析研究了嵌段共聚物聚苯乙烯-异戊二烯-苯乙烯（SIS）／油树脂共混体系的阻尼性质。SIS的硬段聚苯乙烯含量越高，损耗因子（tanδ）峰值温度和粘流温度越高。含有脂肪族系（C5系）石油树脂共混体系的粘流温度比含有氢化芳香族系（C9系）的高。石油树脂的软化点提高，tanδ峰值温度上升。随着石油树脂的含量增大，tanδ峰值增大，并向高温移动，但储能模量（E＇）却先大幅度减小，而后缓慢增大。石油树脂和SIS的软段聚异戊二烯（PI）具有更好的相容性。SIS／N油树脂共混体系的阻尼性能优异，如SIS-A／E120（100／125）在-11～115℃范围内tanδ〉0．3。     

Poly(vinylpyrrolidone): Configurational assignments by one- and two-dimensional NMR spectroscopy

The configurational assignment of poly(vinylpyrrolidone) (PVP) prepared by peroxide-initiated solution polymerization was studied by the combination of one- and two-dimensional NMR spectroscopy. The broad and overlapping ¹H-NMR and ¹³C{¹H}-NMR spectra of PVP were assigned to the configurational triad, pentad (CH, ²CH₂, ³CH₂, and ⁴CH₂ regions), and tetrad (β-CH₂ region) sequences. The configurational assignments of the various carbon resonances were confirmed with the help of two-dimensional experiments such as heteronuclear single quantum correlation (HSQC), heteronuclear single quantum correlation–total correlation spectroscopy (2-D HSQC–TOCSY). The various geminal and vicinal couplings within the configurational sequences were assigned with the help of total correlation spectroscopy (TOCSY low mixing time). The propagation pathway was studied using the ¹³C{¹H}-NMR (carbonyl carbon) and ¹⁵N{¹H}-NMR spectra. The ¹⁵N{¹H} resonance signals were assigned to pentad-level configurational sequences. The results obtained by the analysis of the area under the resonance signals confirmed that poly(vinylpyrrolidone) obeys Bernoullian statistics. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3922–3928, 1999     

聚乳酸接枝改性纳米生物玻璃/PLGA复合材料的制备、表面性质及生物活性

以丙交酯开环聚合原位接枝改性的纳米生物玻璃(PLLA-g-BG)与聚丙交酯-乙交酯(PLGA)复合材料为研究对象, 采用TGA, ESEM和EDX分析其接枝率, 粒子分散性和表面元素分布, 通过将兔成骨细胞种植于材料膜表面进行体外培养, 采用荧光染色法、NIH Image J图像分析软件、MTT法和流式细胞术等手段检测细胞在材料表面的平均黏附数量、扩展面积比、增殖能力和细胞周期的变化, 综合评价新型改性纳米复合材料的生物相容性和生物活性. 结果表明, 聚乳酸表面接枝改性可明显改善纳米生物玻璃粒子的团聚; PLGA中掺入一定比例的改性PLLA-g-BG可明显促进兔成骨细胞的黏附、扩展与增殖; 改性纳米生物玻璃的应用可提高生物可降解聚酯材料的生物相容性和生物活性.     

Investigation of Rheological Properties of Poly(Vinyl Butyral) Solutions in Methacrylic Monomers

Rheological feature of casting polymerizable compositions based on the solutions of poly(vinyl butyral), di(1-methacryloxy-3-chloropropoxy-2-)methylphosphonate, and 2-hydroxypropyl methacrylate at various ratios, which manifests itself in a two-element mechanical model involving viscous strain and plastic yielding, has been determined. The viscosity values of the solutions have been determined from the dependences of shear stress on the shear rate in the temperature range of 30–80°C. It has been determined that the solutions with the specified ratio of FOM-II-to-HPMA and the content of high-molecular component represented by poly(vinyl butyral) from 1 to 5 wt % are most processible at 30°C.     

Poly(vinylpyrrolidone)‐based films grown on copper surfaces

The influence of molecular weight and the amount of the poly(vinylpyrrolidone) (PVP) on the growth of poly(vinylpyrrolidone)–based films on copper surfaces was studied by electrochemical, infrared and electronic spectroscopy, and thermogravimetric methods. Complex polymer/metal ions were deposited onto a copper surface, as the result of the electrochemically generated reaction of copper cations with PVP and SCN^?, in sulfuric acid media. Spontaneous film growth on copper surfaces was generated and characterized as a Cu(II)/PVP/SCN^? complex. Infrared spectra and thermal gravimetric curves of the films generated at + 0.7 V were compared with the chemically synthesized complex, and show the same patterns. The oxidation process can be described as: Cu(0)→Cu(I) and Cu(I)→Cu(II), and the copper complex formed at more positive potentials was characterized as Cu(II)/PVP/SCN^?, with copper bonded to the oxygen atom of PVP and thiocyanate ligand N‐linked. This study focuses on the complex formation on a copper surface in acid media and its characterization through electrochemical and spontaneously generated reactions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2206–2214, 2009     

DNA Separation by Microchip Electrophoresis Using Copolymers of Poly(vinylpyrrolidone) and Hydroxyethylcellulose

Copolymers of poly(vinylpyrrolidone) (PVP) and hydroxyethylcellulose (HEC) were synthesized, with PVP to HEC molar ratios of 3:1, 2:1 and 1:1. The copolymers were tested as separation media in DNA fragment separation analysis by microchip electrophoresis (MCE). Separation efficiency over 3.8×10⁵ for 118 bp has been reached by using the bare channels without the additional polymer coating step. Under optimized separation conditions for longer read length DNA sequencing, the separation ability of the copolymers decreased with decreasing (PVP‐co‐HEC) molar ratio from 3:1 to 2:1 and 1:1. In comparison with (PVP‐co‐HEC) 1:1, the copolymer with (PVP‐co‐HEC) 3:1 ratio showed high separation efficiency. By using a 20 g·L^?1 copolymer with (PVP‐co‐HEC) 3:1 ratio, ΦΧ174‐HaeIII digest DNA marker was successfully separated within 3 min.     

Strong Fluorescence of Poly(N‐vinylpyrrolidone) and Its Oxidized Hydrolyzate

Discovering fluorescence of existing compounds, which are generally regarded as non‐fluorescent, is of important academic and technical significance. This article reports the fluorescence of common compounds containing pyrrolidone ring(s) and their oxidized hydrolyzates. Poly(N‐vinylpyrrolidone) (PVP), polymerized from a very weak fluorescent monomer N‐vinyl‐2‐pyrrolidone (NVP), exhibits strong intrinsic fluorescence. Moreover, the fluorescence of its “hydrolyzate” is dramatically enhanced by about 1000 times. The “hydrolyzate” of N‐methyl‐pyrrolidone (NMP) also exhibits significantly enhanced fluorescence. By studying the chemical structures and fluorescence of the hydrolyzates, the enhanced fluorescence is attributed to the formation of secondary amine oxide. The much stronger fluorescence of the polymers compared to the corresponding small molecular compounds is ascribed to the “aggregation‐induced emission” (AIE) effect of the luminophores. PVP and its oxidized hydrolyzate also show some phenomena different to the common AIE effect. The fluorescence of PVP and its oxidized hydrolyzate shows stimuli response to metal ions and pH values. This study introduces novel fluorescent materials for various potential applications.

     

Size Exclusion Chromatography of Poly(vinylpyrrolidone): I. The Chromatographic Method

Abstract

The optimum size exclusion chromatographic (SEC) method for poly-(vinylpyrrolidone) (PVP) was found to be based upon a stationary phase of diol derivatized silica of pore sizes 3000, 500, and 75Å and a mobile phase of 50:50 (v/v) MeOH/H₂O containing 0.1M-LiNO₃. Sample recovery under identical conditions varied for the commercial packings investigated and was found to be inversely related to molecular weight. The latter phenomenon was rationalized on the basis of a limited number of active substrate sites available for binding. Methanol was found to be a more effective mobile phase modifier than either dimethyl formamide or acetonitrile apparently due to its ability to function as a proton donor in hydrogen bonding with PVP. Chromatographic evidence for the existence of semipolyampholyte character in PVP is presented. A procedure for the construction of a column set log-linear in calibration and of extended dynamic range is described and is based upon hydrodynamic volume theory.     

可控交联聚醚醚酮的动态力学性能

动态力学分析技术(DMA)是研究聚合物性能的重要方法之一．动态力学实验可以检测聚合物的玻璃化转变温度和次级松弛过程,直接与聚合物的链结构和聚集态结构密切相关,聚合物的化学组成、支化和交联、结晶和取向、增塑和共混等结构因素的变化,都与分子运动状态的变化密切相关,而分子运动的变化又能灵敏地反映在动态力学性能上,     

Dilute Solution Properties of Poly(methacrylonitrile-co-styrene) and Poly(acrylonitrile-co-styrene)

Poly(methacrylonitrile-co-styrene) (PMANS) and Poly(acrylo-nitrile- co- styrene) (PANS) having 1:1 composition were prepared with free-radical initiators. The polymers were fractionated into fractions having narrow molecular weight distribution. The dilute solution properties of the fractionated copolymers were studied by light scattering, viscometry, and osmometry in solvents (methyl ethyl ketone, dimethylformamide, and acetone), [n]-M _w and(r²)_w ^l/2?M _w relationships have been established. The validity of the various graphical methods for the determination of Flory′s constant, K _θ were observed.

From the values of the steric factors it was noticed that the copolymer coil of PANS is stiffer than that of PMANS.     

Surface Properties of Poly(vinyl alcohol) with Iron(III)chloride Before and After UV-Irradiation

Summary: Surface properties of poly(vinyl alcohol) (PVA) with low content of FeCl₃ (1, 5 wt.%) were studied by measurements of contact angles and atomic force microscopy. The results of contact angles and the surface free energy calculations revealed that the hydrophilicity of the surface of PVA films depended on the content of iron (III) chloride in these polymeric films. Introduced salt also affected photochemical reactions in poly(vinyl alcohol). Photooxidation of PVA was more effective in the presence of FeCl₃ because of formation of reactive chlorine atoms, which were capable of initiating new reactions. Also the morphology and roughness parameters of PVA film changed when iron (III) chloride was added.     

Poly(vinylpyrrolidone)-coated silica: A versatile,polar stationary phase for HPLC

Summary Poly(vinylpyrrolidone) (PVP) is immobilized on both, small- and large-pore silicas by thermal treatment, γ-radiation, or peroxide initiated polymerization. The hydrolytic stability of such a highly polar stationary phase significantly exceeds that of a comparable phase prepared by the chemical reaction of silica with a pyrrolidone ethyl dimethylchlorosilane silanization reagent. The properties of the different PVP-silicas are evaluated by elemental analysis, spectroscopy, and chromatography. Columns of PVP-silica packings can be used in several modes: a) under normal-phase conditions as a polar bonded stationary phase, b) under reversed-phase conditions, for the separation of organic proton-donor and hydrogen-bonding compounds, c) for the aqueous size exclusion chromatography of proteins, and d) with salt gradients for the hydrophobic interaction chromatography of proteins. The minimum observable reduced plate-height of PVP-silica columns is about 3. Double-layer polymer coating experiments using PVP-silica covered with poly(methyloctadecylsiloxane) have been performed to study diffusion and shielding effects of different polymer layers in the stationary phase. Depending on separation conditions, one or the other polymer governs the retention process. A mixed selectivity was observed in a reversed phase mode with acidic eluents.     

气/液界面上十六烷基三甲基溴化铵水溶液的动态表面性质

用最大泡压法测定了不同温度下浓度低于cmc时十六烷基三甲基溴化铵水溶液的动态表面张力.发现当浓度低于0.10 mol·m-3时动态吸附量ΓT遵s从由Henry吸附等温式导出的动态表面状态方程.在浓度位于0.10至0.80mol·m-3的较大范围内,Tt遵从从Langmuir等温式导出的动态表面状态方程.在吸附的后期十六烷基三甲基溴化铵分子在溶液表面上的吸附遵从混合动力学控制机理.从表观扩散系数计算出吸附为混合动力学控制机理时吸附能垒为6.7～7.1 kJ·     

Poly(N‐vinylpyrrolidone)–polydimethylsiloxane amphiphilic ABA triblock copolymers

Triblock copolymers of N‐vinylpyrrolidone (NVP) and polydimethylsiloxane (PDMS) were synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization using two different types of difunctional telechelic PDMS‐based dixanthate macroinitiators. The incorporation of PDMS into the triblock copolymers was evidenced by ¹H NMR spectroscopy and varied between 4 mol % and as high as 20 mol %, dependent on reaction time and monomer conversion. The copolymer homogeneity was characterized in terms of molecular weight distribution determined by GPC to estimate the level of control over the chain length. Monomodal molecular weight distributions were observed, and ¹H NMR spectroscopy indicated the copolymers had number average molecular weights (M_n) ranging between 28,000 and 160,000 g/mol. In addition, thin film phase separation and critical micelle concentrations for these copolymers were analyzed via transmission electron microscopy and surface tension measurements, respectively. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3387–3394     

Poly(N‐vinylpyrrolidone)‐Modified Surfaces for Biomedical Applications

Poly(N‐vinylpyrrolidone) (PVP), an important water soluble synthetic polymer, has many desirable properties including low toxicity, chemical stability, and good biocompatibility. Since PVP is hemocompatible and physiologically inactive, it has been used as a blood plasma substitute. Surface modification with PVP has been investigated extensively over the past few years as a means of preventing nonspecific protein adsorption. PVP may therefore be seen as a promising antifouling surface modifier comparable to poly(ethylene glycol) (PEG). In this review, various approaches for the design and preparation of PVP‐modified surfaces are summarized and potential biomedical applications of these PVP‐modified materials are indicated. Finally, some perspectives on future research on PVP for surface modification are discussed.

     

Dynamic Membranes Based on Poly(N-Isopropylacrylamide-co-Heptadecyl Vinyl Ketone): Preparation and Properties

Dynamic membranes were prepared from poly(N-isopropylacrylamide-co-heptadecyl vinyl ketone) having a lower critical solution temperature in an aqueous solution and being a micelle-forming surfactant. The dependence of the critical concentration of the copolymer micellization on temperature was shown to have an extreme character, with a minimum at the lower critical solution temperature of the copolymer. The dynamic membranes are formed on both the hydrophilic (cellulose) and hydrophobic (polyacrylonitrile) supports. For the penetrants studied, it was found that the dynamic membrane formed on the hydrophobic support favors the rejection of a PEG₆₀₀₀, while that formed on the hydrophilic support rejects more effectively albumin and sodium cellulose sulfoacetate. We failed to realize a completely reversible thermal control of transport properties of the dynamic membranes obtained, while it was readily accomplished for the membranes obtained by grafting N-isopropylamide onto a cellulose matrix.