离子型表面活性剂与疏水缔合聚丙烯酰胺的相互作用

通过动态流变、幂律模型、动/静态激光光散射以及荧光光谱考察了丙烯酸十八酯(ODA)、丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)经超声辅助(Ultrasonic assist)自由基共聚制得的疏水缔合聚丙烯酰胺(UHAPAM)的动态流变性及其与阴阳离子型表面活性剂(十二烷基硫酸钠(SDS)和十六烷基三甲基溴化铵(CTAB))之间相互作用关系。结果表明,这种假塑性流体的临界聚集浓度(CAC)为0.27%。当UHAPAM水溶液浓度高于CAC时,SDS影响分子间疏水缔合,使水溶液表观粘度下降;CTAB反而改善疏水缔合性,使表观粘度明显增加,但增粘效果越来越缓和。表面活性剂均使溶液触变性降低。同时,形状因子(〈Rg〉/〈Rh〉)在SDS-UHAPAM体系里随SDS浓度的增加而增加,聚合物分子线团变得相对舒展;而在CTAB-UHAPAM体系里则随CTAB浓度增加而出现最低值,聚合物分子链段历经一个卷缩然后舒展的过程。在SDS和CTAB胶束中加入UHA-PAM,SDS聚集数先减小后增大,而CTAB聚集数则持续增加。     

醋酸纤维素/聚乙烯基亚胺共混微孔滤膜对Cu2+的吸附

以二醋酸纤维素N(CA)／聚乙烯基亚胺(PEI)共混制备微孔滤膜，利用PEI对重金属离子的螯合作用吸附水溶液中的Cu^2 ，实验考察了吸附时间、pH对Cu^2 静态吸附性能的影响．膜对Cu^2 的等温吸附符合Langmuir型吸附，其饱和吸附量取决于膜中PEI的含量．     

不同碳源多孔碳纤维制备及其吸附性能

先用静电纺丝法制备聚丙烯腈(PAN)、聚乙烯醇(PVA)和聚乙烯吡咯烷酮(PVP)基高分子纤维,然后将其碳化制备出不同碳源的多孔碳纤维材料。使用X-射线衍射仪、红外光谱仪、差示扫描量热仪和N₂吸脱附分析仪等手段表征了碳纤维材料的结构和性能。结果表明,PAN基碳纤维的比表面积最大(113.5 m²/g)、微孔较多,对刚果红的吸附量最大(560.2 g/kg)。根据吸附动力学模型和吸附等温线的分析结果,碳纤维对刚果红的吸附属单层吸附。结果还表明,温度越高材料的吸附速率越高但是吸附量没有明显的变化;在酸性条件下PVA基碳纤维保持较高的吸附活性,而PAN基碳纤维则与之相反;刚果红水溶液的pH值对PVP基碳纤维吸附活性的影响很小。     

3-(苯胺基甲基)-苯并噻唑-2-硫酮的缓蚀性能及吸附作用

为了研究缓蚀剂分子与金属表面的吸附作用,以2-巯基苯并噻唑、甲醛和苯胺为原料在微波辐照下合成了3-(苯胺基甲基)-苯并噻唑-2-硫酮(PAMMOA),利用失重法和动电位极化曲线对合成缓蚀剂的缓蚀性能进行了测试,并利用分子动力学模拟和量子化学计算方法对其在Fe表面的吸附作用进行了探讨。结果表明:该缓蚀剂能够有效抑制饱和CO2环境下、模拟腐蚀介质中N80钢的腐蚀,属于混合型缓蚀剂;其分子中最高占据轨道(HOMO)的电荷主要分布在巯基苯并噻唑环上,同时分子中的苯胺基上也有一定的电荷分布,而其最低空轨道(LUMO)的电荷主要分布在巯基苯并噻唑环上,当其分子与Fe金属表面发生吸附时,分子中的巯基苯并噻唑环和苯胺基在同一平面上,并平行吸附于Fe表面。     

电纺复合纳米纤维对难溶药物增溶促渗作用研究

以75%(体积比)的乙醇水溶液为溶剂,将聚乙烯吡咯烷酮PVP K30、十二烷基硫酸钠(SDS)、阿魏酸(FA)按质量比30:1:10:w/v%配成共溶纺丝液,采用电纺工艺制备出多组分复合纳米纤维.场扫描电镜观察表明纤维膜具有立体三维连续网状结构,纤维结构均一、表面光滑,96%纤维直径在140～280nm之间.X射线晶体衍射和差示扫描量热结果表明FA和SDS能以分子状态高度复合分散于PVP纤维基材中,衰减全反射红外扫描结果表明SDS、FA、PVP之间能够通过氢键、静电吸引、疏水性能发生相互作用而复合.体外溶出与透膜结果表明复合纳米纤维具有改善药物溶出特征、促进药物透膜吸收的功能.     

分子印迹氨基功能化纳米Fe_3O_4高分子磁性复合材料的合成及其对海水中2,4,6-三氯苯酚的吸附性能

为了实现海水中2,4,6-三氯苯酚(2,4,6-TCP)的选择性吸附和去除,采用超声协助悬浮聚合法以2,4,6-三氯苯酚为模板制备了分子印迹氨基功能化纳米Fe3O4高分子磁性复合材料(nFe3O4@MIPNH2-polymer)。通过元素分析(EA)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱分析、透射电子显微镜(TEM)、振动样品磁强计(VSM)等手段对nFe3O4@MIPNH2-polymer的组成、结构、形貌、磁性等进行表征,并研究了其应用于吸附和去除海水中2,4,6-三氯苯酚(2,4,6-TCP)污染物的性能。结果表明:合成的nFe3O4@MIPNH2-polymer平均粒径约为800nm,饱和磁化强度为32.6emu·g-1;水溶液中2,4,6-TCP的饱和吸附量为105.26mg·g-1,高于非分子印迹氨基功能化纳米Fe3O4高分子磁性复合材料(nFe3O4@NH2-polymer)的饱和吸附量(76.92mg·g-1),nFe3O4@MIPNH2-polymer对2,4,6-TCP的等温吸附线大体符合Langmuir模型。吸附热力学研究表明,nFe3O4@MIPNH2-polymer对2,4,6-TCP的吸附过程是自发的吸热熵增过程;吸附过程可在5min内达到平衡,动力学数据和准二级动力学模型符合较好;其吸附过程去除2,4,6-TCP的活化能为78.0kJ·mol-1。海水中的共存物质对吸附2,4,6-TCP几乎无干扰,nFe3O4@MIPNH2-polymer经洗脱后可以循环使用5次以上。nFe3O4@MIPNH2-polymer能高选择性地有效去除海水中的2,4,6-TCP。     

气体工业名词术语

吸附(Adsorption)气体分子碰撞固体表面，失去一定的动能而被滞留在固体表面的现象叫吸附。吸附作用因吸附分子(或称吸附质)和固体(或称吸附剂)的相互作用力的性质而区分为物理吸附和化学吸附两种。物理吸附的特点是：气体分子可以吸附凝结在固体表面任何位置上，与吸附剂之间的作用力是分子之间相互作用的内聚力(或称范德瓦耳力)或凝聚力。这种力比较弱，因而分子吸附时放出的热量比较小。吸附剂的选择依据是吸附物质的极性、沸点、分子直径、吸附剂孔径、吸附温度等多项因素。在特种气体提纯工艺中，利用固体吸附作用可将气体中的杂质除到10^-6～10^-8数量级。化学吸附的特点是：分子多半解离成原子或原子基吸附于固体表面上。     

PVP和SDS混合分散剂对水基TiO_2悬浮液分散稳定性的影响

运用"两步法"制备水基TiO2悬浮液,通过同时添加十二烷基硫酸钠(SDS)和聚乙烯吡咯烷酮(PVP)两种分散剂来提高悬浮液的分散稳定性。测量了SDS与PVP两种分散剂以不同质量比混合后溶液的表面张力;测量了水基TiO2悬浮液的吸光度和表面zeta电位,并采用静置沉淀法研究了不同质量比的混合分散剂对TiO2悬浮液稳定性的影响。实验结果表明,PVP与SDS的质量比会影响混合分散剂的稳定效果,在PVP和SDS质量比为1∶2时,混合分散剂对TiO2悬浮液稳定性的提升最明显。对实验结果的分析表明,PVP与SDS之间由于协同作用形成的静电和空间位阻的双重作用可能是提高TiO2悬浮液分散稳定性的主要原因。     

环糊精二聚体与双支化两亲聚合物包合体系的构筑

将实验室自制的环糊精二聚体(66βCDsu)与双支化两亲聚合物(P(AM/BHAM/NaA))加入到水溶液中,发生包合作用构筑包合体系。研究该体系的增黏及溶液流变学特性,并采用荧光光谱仪、扫描电镜及差示扫描量热仪等研究包合体在溶液中的包合机制及结构形态。结果表明,由于P(AM/BHAM/NaA)中1个疏水单体中存在2个疏水基团(正十六烷基和苄基),因此环糊精与疏水单体BHAM最大摩尔包合比为2∶1,完全包合后溶液中没有游离态疏水基团,因此溶液不存在临界聚集浓度(CAC)。当环糊精与BHAM摩尔包合比为1∶1,体系存在明显的CAC,这是由于环糊精首先包合双支化疏水单体中的苄基形成包合体,而正十六烷基依然存在于水溶液中。当P(AM/BHAM/NaA)浓度为800mg/L时,该体系中存在2种聚集方式,一种是疏水基团的疏水缔合;另一种是包合作用。通过扫描电镜证明了不同体系的微观聚集形态。     

交联壳聚糖微球对表面活性剂的吸附性能研究

以壳聚糖为原材料,采用反相悬浮法制备了交联壳聚糖微球(ACCMs),并将优化制备的交联壳聚糖微球用于吸附水体中阴离子表面活性剂(AS),探究ACCMs对十二烷基苯磺酸钠(SDBS)、十二烷基硫酸钠(SLS)和苯十二烷基磺酸钠(SDS)3种阴离子表面活性剂的吸附性能。实验结果表明,酸性介质有利于吸附的进行;静态吸附360 min后,吸附反应趋于平衡;吸附过程符合Lagergren二级吸附动力学方程;ΔG均为负值,吸附反应可以自发进行。吸附等温模型符合Langmuir等温式,可以用单分子层吸附理论加以解释。ACCMs对SDBS、SLS、SDS的饱和吸附容量分别为793,789和341 mg/g。综上所述,ACCMs对阴离子表面活性剂有较强的吸附能力,可用于环境水体中阴离子表面活性剂的吸附处理。     

Self-association behaviour of protein:surfactant systems in alcohol/water mixtures

The effect of the addition of short-chain monohydric alcohols (ethanol and propan-2-ol) to the protein:surfactant system lysozyme:sodium dodecyl sulfate (Lz:SDS) in aqueous solution was investigated using a conductometric technique. A second protein:surfactant system, bovine serum albumin:SDS (BSA:SDS) was also investigated so that the effect of a different protein conformation and composition could be compared. The critical aggregation concentration (CAC) of the protein forming the complex and the critical micelle concentration (CMC *) of SDS in the presence of protein, at different alcohol concentrations, were determined. It was found in both cases that the addition of alcohol does not produce a significant change in the CAC, whereas the CMC * displays variation with alcohol concentration that shows an inversion in the ranges 0.05-0.06 ethanol mole fraction and 0.02-0.03 propan-2-ol mole fraction. This suggests that, in contrast with the CAC behaviour, the major factor that drives SDS micellization in the presence of protein is the variation in water structure. Results also suggest that it occurs in the same way for both proteins, where electrostatic interactions are the main force in the formation of the complex. Conversely, hydrophobic interactions play the dominant role at the micellization stage, and only the extent of the interaction between protein:surfactant aggregates and surfactant species seems to depend on protein nature.     

Controlled synthesis of gold nanosnakes assisted by poly(vinyl pyrrolidone)–sodium dodecyl sulphate aggregations

Anisotropic single-crystalline gold nanosnakes were synthesised in poly(vinyl pyrrolidone) (PVP)–sodium dodecyl sulphate (SDS) aggregation aqueous solution by reducing HAuCl₄ with PVP without any additional reducing agent. The crystal structures, growth process and the influence of SDS concentrations on the growth of gold nanosnakes have been investigated by X-ray diffraction and transmittance electron microscopy. In this approach, the peculiar structure of PVP–SDS aggregations is indispensable for the asymmetrical formation of gold nanosnakes. Without PVP–SDS aggregations, only long tortuous gold nanobelts were synthesised. When SDS concentration was increased from 3 to 10?mM, gold nanosnakes, nanokites and nanoplates were fabricated. To the best of our knowledge, this is the first report on the SDS-induced shape transformation from snake-like to plate-like at fixed low HAuCl₄ concentration in PVP–SDS aggregation aqueous solutions. Moreover, the gold nanosnakes exhibit excellent electrocatalytic property towards the oxidation of methanol indicating their potential applications in fuel cells, catalysis, biosensing and nanodevices.     

Role of poly(<Emphasis Type="Italic">N</Emphasis>-vinyl-2-pyrrolidone) as stabilizer for dispersion of graphene via hydrophobic interaction

Stable aqueous dispersion of chemically reduced graphene is simply obtained by reducing GO solution in the presence of PVP. Prepared aqueous graphene dispersion was optically clear and stable for several months without any aggregation or precipitation. Graphene/PVP assembly shows decreased optical transmittance (47% at 600 nm) and quenching of photoluminescence of parent GO (8.5% at 375 nm) after reduction. Raman analysis confirms that reduction of GO to graphene is efficient in the presence of PVP. Both DLS and AFM analysis confirm that there is efficient and overall interaction between chemically reduced graphene plates and PVP chains. Hydrophobic interaction between graphene and PVP might be responsible for this solubilization of chemically reduced graphene in solution.     

黏度法研究非离子型高分子对盐水溶液中油酸钾聚集行为的影响

测定了在不同浓度聚丙二醇(PPG)、聚乙二醇(PEG)和聚乙烯基吡咯烷酮(PVP)存在条件下油酸钾盐水溶液的黏度,研究了非离子型高分子对盐水溶液中油酸钾表面活性剂聚集行为的影响,结果表明,随着非离子型高分子的加入,油酸钾盐水溶液的黏度迅速下降,但是程度显著不同,不仅如此,加入更加疏水的聚丙二醇以后,油酸钾盐水溶液黏度下降的程度最低。由此可见,非离子型高分子疏水程度不是导致表面活性剂盐水溶液黏度下降的唯一因素,高分子与表面活性剂疏水和亲水基团之间的相互作用,以及由此形成的高分子/表面活性剂聚集体的形态,是决定表面活性剂盐水溶液黏度下降最主要的原因。     

Temperature-responsive Pickering foams stabilized by poly(N-isopropylacrylamide) nanogels

Poly(N-isopropylacrylamide) (PNIPAM) nanogels were synthesized by emulsion polymerization using sodium dodecyl sulfate (SDS). After removal of SDS by dialysis, the surface tensions of the PNIPAM nanogel aqueous dispersions were measured at various temperatures by the pendant-drop method, and it was found that the surface tensions of the nanogel dispersion below the lower critical solution temperature (LCST) of PNIPAM were much smaller than those of water and comparable to those of the SDS aqueous solution. The stability of the aqueous foams generated by nitrogen bubbling thorough the PNIPAM nanogel dispersion was investigated below and above the LCST of PNIPAM. The foam prepared below the LCST was stable in some degree, whereas almost no foam was formed above the LCST. Moreover, the foam prepared below the LCST was quickly collapsed by changing the temperature above the LCST. This rapid defoaming represents that the surface activity of the PNIPAM nanogel can be switched off by the temperature increase across the LCST.     

Aggregation behavior of betaine-amphiphiles in the presence of polyvinylpyrrolidone

The aggregation behavior of zwitterionic surfactant dodecylbetaine (C₁₂BE) with and without polyvinylpyrrolidone (PVP) has been investigated by means of surface tension and steady-state fluorescence techniques. It shows that addition of PVP results in a decrease in the aggregation number of C₁₂BE micelle and “hydrophobic index” (I₁/I₃) of the probe (pyrene and pyrene-1-carboxaldehyde). PVP molecules are responsible for the phenomena: they bind to the surface of the micelle and prevent the rapid exchange of amphiphiles between micelles and water phase. There are two transition points in the plot of surface tension vs. concentration of C₁₂BE in the presence of PVP. The results indicate that the association takes place between PVP and C₁₂BE when the C₁₂BE concentration is above a critical aggregation concentration (CAC).     

Increasing the aqueous solubility of acetaminophen in the presence of polyvinylpyrrolidone and investigation of the mechanisms involved

It was shown that the aqueous solubility of acetaminophen in the presence of polyvinylpyrrolidone (PVP) increased. The solubility at 25°C increased from 14.3 mg mL^-1 in the absence of PVP, to 19.7 mg mL^-1 in the presence of 4% w/v PVP, and to 26.7 mg mL^-1 in the presence of 8% w/v PVP. Dialysis studies indicated that there is a potential of binding between PVP and acetaminophen in their aqueous solutions. Dialysis studies also revealed that the nature of interaction between PVP and acetaminophen is physical and reversible, and there was no strong binding between PVP and acetaminophen in their solutions. Infrared spectroscopy of acetaminophen/PVP solid dispersion indicated that the mechanism of interaction between PVP and acetaminophen is via hydrogen bonding. Therefore, the increase in solubility of acetaminophen in the presence of PVP is probably attributed to its ability to form a water-soluble complex with PVP.     

Surfactant-mediated growth of nanostructured zinc oxide thin films via electrodeposition and their photoelectrochemical performance

Zinc oxide (ZnO) thin films were electrodeposited from an aqueous zinc acetate solution onto fluorine-doped thin oxide (FTO) coated conducting glass substrates. The effect of organic surfactants like polyvinyl pyrrolidone (PVP), sodium dodecyl sulfate (SDS), polyethylene glycol (PEG), ethylene glycol (EG) and polyvinyl alcohol (PVA) on their structural, morphological, optical and photoelectrochemical properties was studied. The x-ray diffraction patterns revealed the formation of phase-pure ZnO thin films. The films deposited using organic surfactants exhibit different surface morphologies. It was observed that the organic surfactants play important roles in modifying the surface morphology and size of the crystallites. A compact granular morphology was observed for the ZnO samples grown without organic surfactants. The films exhibit nanoparticles of size 100-150?nm for PVP, EG and PVA mediated growth. The vertically aligned thin and compact hexagonal crystallites stem from the SDS, whereas microporous corrugated morphology is observed for PEG-mediated growth. All the samples exhibit room temperature photoluminescence (PL). Oxygen vacancies contribute to the active luminescent centers for the emission of green light in ZnO thin films. PL gets quenched for the SDS surfactant. All the samples were post-treated with ethanol to remove stray surfactant molecules. FTIR study was used to confirm the removal of adsorbed surfactant molecules from the samples. Moreover the samples are photoelectrochemically (PEC) active and exhibit the highest photocurrent of 231?μA, a photovoltage of 492?mV and 0.42 fill factor for the ZnO:SDS films.     

Solid State and Dissolution Rate Characterization of Co-Ground Mixtures of Nifedipine and Hydrophilic Carriers

ABSTRACT

Co-ground powders of the poorly water-soluble drug nifedipine and a hydrophilic carrier, [partially hydrolyzed gelatin (PHG), polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), urea or Pluronic F108] were prepared in order to improve the dissolution rate of nifedipine. The effects of type of grinding equipment, grinding time, and type of hydrophilic carrier on the crystallinity of nifedipine (x-ray diffraction and differential scanning calorimetry) on the interaction between drug and carriers (differential scanning calorimetry), on the particle size and appearance (scanning electron microscopy), on the wettability (contact angle measurements), and on the drug release were investigated. Grinding nifedipine together with these carriers improved the dissolution rate. PHG-ground mixtures resulted in the fastest dissolution rate followed by PVP, SDS, HPMC, Pluronic, urea, and PEG. This effect was not only due to particle size reduction, which increased in the order PHG < PEG = SDS < Pluronic < drug < urea < HPMC < PVP, but also resulted from the ability of some carriers (PVP and HPMC) to prevent reaggregation of the finely divided drug particles. PVP, HPMC, and PHG formed a powder with amorphous drug. The carriers improved the wettability of the ground products in the order HPMC < drug < urea < PVP < SDS < PHG < PEG < Pluronic. Differential scanning calorimetry (DSC) measurements gave valuable information about the nature of drug crystallinity and the interactions with the carriers within the ground mixtures.     

Light Scattering Study of Aqueous Poly(Vinyl)pyrrolidone–Fullerene C70 Solutions

Abstract

It was shown by static and dynamic light scattering that poly(vinyl)pyrrolidone (PVP) molecules form large intermolecular complexes (clusters) with C₇₀ in aqueous solutions. The molecular weights and dimensions of PVP–C₇₀ clusters increase both with the increase of fullerene content and the molecular weight of the matrix PVP. However, two different diffusion coefficients were detected by dynamic light scattering. The slow mode was explained as diffusion of large PVP–C₇₀ clusters. The fast mode represents free PVP molecules in solution. Dimensions of clusters revealed in aqueous PVP–C₇₀ solutions are less than that for PVP–C₆₀ by factor of 2.5–3.