反气相色谱法表征漆酚钛螯合高聚物的表面性质

漆酚钛螯合高聚物(UTP)具有优异的耐强酸、耐强碱、耐盐类溶液、耐多种有机溶剂和耐热性能。为进一步扩大其应用领域提供理论和实验依据,采用反气相色谱法(IGC)测定了UTP在70、80、90、100和110 ℃下的表面色散自由能和表面Lewis酸碱常数。以正戊烷(C5)作为标定色谱死时间的探针分子,正己烷、正庚烷、正辛烷和正壬烷作为非极性探针分子,计算了不同温度下UTP的色散表面自由能;以四氢呋喃、丙酮和三氯甲烷作为极性探针分子,计算得到了UTP表面的酸碱作用吸附自由能和吸附焓。实验结果表明: 在70、80、90、100和110 ℃时UTP的色散表面自由能分别为37.68、33.53、35.92、24.01和31.32 mJ/m2; UTP为弱的Lewis碱,Lewis酸常数Ka为0.1853,碱常数Kb为0.9662。这一结果对研究漆酚金属螯合高聚物的表面性质与应用具有指导作用。     

反相气相色谱法表征聚丁二烯橡胶的表面性质

采用反相气相色谱技术测定了聚丁二烯橡胶的表面性质。以正己烷、正庚烷、正辛烷、正壬烷作为非极性探针测定其表面色散自由能,以二氯甲烷、三氯甲烷、丙酮、乙酸乙酯、乙醚和四氢呋喃作为极性探针测定其路易斯酸碱常数。经计算得出聚丁二烯橡胶在303、313、323、333和343 K的表面色散自由能分别为47.07、46.46、45.85、45.60和45.09 mJ/m2。结果表明,聚丁二烯橡胶表面色散自由能随着温度的升高呈线性降低,路易斯酸常数Ka为0.34,碱常数Kb为1.77,总酸碱作用能力2.11,该聚合物为弱碱性Lewis两性聚合物材料。此外还计算出聚丁二烯橡胶的酸碱作用吸附自由能（~ΔGsa）和吸附焓（~ΔHsa）。     

反相气相色谱法表征1-烯丙基-3-甲基氯代咪唑离子液体的表面性质

采用反相气相色谱(IGC)技术研究了不同温度下1-烯丙基-3-甲基氯代咪唑(［AMIM］Cl)的表面性质。以正己烷、正庚烷、正辛烷和正壬烷作为非极性探针分子测定［AMIM］Cl在343.15、353.15、363.15和373.15 K温度下的表面色散自由能;以二氯甲烷、三氯甲烷、丙酮、乙酸乙酯、四氢呋喃作为极性探针分子测定离子液体Lewis酸碱性质,并测定了吸附自由能和吸附自由焓变等热动力学参数。实验结果表明,［AMIM］Cl的酸解离平衡常数Ka为0.34,碱解离平衡常数Kb为1.68,其表面呈Lewis两性偏碱性特点。在343.15、353.15、363.15和373.15 K温度下,［AMIM］Cl的表面色散自由能分别为52.26、50.82、46.08和42.05 mJ/m2。这一结果对研究离子液体的表面性质及应用有指导作用。     

反气相色谱法研究煤直接液化残渣经分级提取前后的表面性质变化

采用反气相色谱法（IGC）分别对煤直接液化残渣（DCLR）脱灰处理后不溶物、正己烷不溶物、甲苯不溶物、四氢呋喃不溶物的表面性质进行表征。基于非极性探针净保留体积V_n分别采用Dorris-Gray方法和Schultz方法得到表面色散自由能,基于极性探针V_n得到吸附焓△H^sp,并通过△H^sp作图计算得到酸常数K_a和碱常数K_b。结果表明,经溶剂分级提取后表面色散自由能、K_a和K_b均发生明显变化。而DCLR呈现两性偏碱性这一特征并未随分级提取发生改变。IGC作为一种动力学吸附技术,可快速准确表征DCLR在经分级提取过程中表面性质的变化,相同温度下应用Dorris-Gray方法得到DCLR表面色散自由能略高于Schultz方法。     

镁铝水滑石及其改性产物的表面性质的研究

采用共沉淀法制备了n_Mg/n_Al比为2∶1镁铝水滑石(Mg/Al-HTlc),经500 ℃焙烧后得到镁铝复合氧化物(C-HT),并用十二烷基苯磺酸钠(SDBS)对复合氧化物进行了改性(M-HT)。通过反相气相色谱法(IGC)对Mg/Al-HTlc、C-HT和M-HT的表面性质进行了研究,定量计算了表面吸附自由能、表面能色散组分以及表面自由能特征分量。结果表明,三者的表面自由能以及色散能的大小顺序为：C-HT＞Mg/Al-HTlc＞M-HT;温度对非极性分子与Mg/Al-HTlc间的色散能影响不大,而非极性分子与C-HT和M-HT间的色散能均随温度的升高而降低;极性分子与固定相的吸附作用包括色散能和吸附自由能特征分量两部分,表面改性会使Mg/Al-HTlc的自由能特征分量降低。     

反气相色谱法测定环氧树脂的表面张力和溶解度参数

采用反气相色谱(IGC)测定了环氧E51树脂在30、40、50和60 ℃下的表面张力和溶解度参数。采用Schultz法,以正癸烷、正壬烷、正辛烷和正庚烷为非极性溶剂探针,计算了不同温度下环氧E51树脂的色散表面张力。根据Good-van Oss方程,以甲苯为碱性探针,二氯甲烷为酸性探针,计算得到环氧E51树脂的极性表面张力。结果表明,环氧E51树脂的色散表面张力和极性表面张力均随着温度的升高而线性降低。根据不同溶剂探针与树脂间的Flory-Huggins相互作用参数,采用DiPaola-Baranyi和Guillet方法计算得到环氧E51树脂在不同温度下的溶解度参数,其在30、40、50和60 ℃下分别为11.78、11.57、11.48和11.14 MPa1/2。根据表面张力、内聚能和溶解度参数的相互关系,计算得到不同温度下溶解度参数的色散和极性分量。结果发现,环氧E51树脂的溶解度参数的色散分量大于极性分量,且均随着温度的升高而降低。     

反气相色谱法测定锌镁铝类水滑石的表面性能

采用水热合成法制备了锌镁铝类水滑石(ZnMgAl-HTLC),利用X射线衍射仪(XRD)对ZnMgAl-HTLC的晶体结构进行了表征,并以一系列非极性和极性分子为探针分子,采用反气相色谱法(IGC)研究了ZnMgAl-HTLC的表面性能.结果表明:XRD特征衍射峰窄、尖、高,水热合成法能够制得纯度较高的ZnMgAl-HTLC; ZnMgAl-HTLC表面吸附自由能小于零,表面色散自由能最大为6.02 mJ/m²,酸碱作用自由能最大为5.33 kJ/mol,吸附焓为43.6 kJ/mol,吸附熵为0.15 kJ/mol.本文的反气相色谱方法对研究锌镁铝类水滑石的表面性能具有重要的指导意义.     

反相气相色谱法研究1,3,5-三氨基-2,4,6-三硝基苯的表面特性

采用反相气相色谱技术(IGC)研究了4种不同粒度的1,3,5-三氨基-2,4,6-三硝基苯(TATB)的表面性质。4种不同粒度的TATB表面自由能的色散分量（γds）随着温度的升高而增加;粒度越大的粒子,其色散自由能上升越快;在较高温度下,粗颗粒TATB显示了更强的色散作用(γds=193.2 mJ/m2,353 K),粒度最小的亚微米TATB显示了最弱的色散作用(γds=64.0 mJ/m2,353 K)。由于制备方法不同和粒子大小的差异,4种TATB的表面酸碱性质显示了明显的差别,细颗粒TATB表面有较强的亲电子特性;而其他3种TATB在极性探针分子的作用下的吸附均表现为吸热吸附,表现出在分子内和分子间具有强烈的相互作用,其Ka和Kb值均为负。     

固体的表面能及其亲水/疏水性

固体表面的亲水/疏水性质与表面分子与水之间的固/液界面相互作用自由能以及水介质中表面分子与空气之间的固/(液)/气界面相互作用自由能密切相关.水介质中固体表面与水之间存在范德华引力或疏水引力,与气泡之间存在范德华斥力、疏水引力以及静电斥力.在Lifshitz-范德华(LW)相互作用自由能、Lewis酸-碱(AB)相互作用自由能以及静电(EL)相互作用自由能3者之中,AB相互作用自由能比其它两者要大2～3个数量级以上.与固体表面能Lewis酸-碱分量相关的亲水指数√r_s~++√r_s~-可以成为衡量固体表面亲水/疏水性质的重要判据,水介质中固体表面疏水的必要条件是√r_s~++√r_s~-＜5mJ~(1/2)/m,指数大于或接近5mJ~(1/2)/m的表面必然是亲水的.     

两亲聚合物表面的反相气相色谱分析

采用反相气相色谱探针技术研究了苯乙烯－氧乙烯－苯乙烯三嵌段两亲聚合物的表面物理化学性质。包括表面吸附热力学函数,表面能的色散分量以及表面分子链与探针的分子间相互作用,。探讨了共聚物中亲油性链段聚苯乙烯（PS）和亲水性链段聚氧乙烯（PEO）的组成比例与其表面性质的关系。结果表明共聚物表面组成中随PEO含量的增加,其表面能增大,表面分子链与探针分子的相互作用增强,表面吸附能力也增强。     

Surface characterization of poly(methyl methacrylate-co-n-butyl acrylate-co-cyclopentylstyryl-polyhedral oligomeric silsesquioxane) by inverse gas chromatography

The surface properties of poly(methyl methacrylate-co-n-butyl acrylate-co-cyclopentylstyryl polyhedral oligomeric silsesquioxane) (poly(MMA-co-BA-co-styryl-POSS)) were studied by means of inverse gas chromatography (IGC) using 10 non-polar and polar solvents as the probes. Thermodynamic parameters of adsorption, e.g., specific retention volume, the dispersive component of the surface free energy, the specific interaction contribution to the free energy of adsorption and the acid/base constants were obtained to investigate the interactions between the surfaces of the copolymers and different solvents. It was found that incorporation of styryl-POSS into polymer resulted in increasing interactions between polymers and solvents, dispersive component of surface free energy of polymer and acidity of the surfaces of the polymers. The more the styryl-POSS were embedded, the stronger the interaction between the polymer surface and solvent, the dispersive component of the surface free energy and the acidity of the polymer surface were.     

Comparison of Dorris-Gray and Schultz methods for the calculation of surface dispersive free energy by inverse gas chromatography

Inverse gas chromatography (IGC) is an important technique for the characterization of surface properties of solid materials. A standard method of surface characterization is that the surface dispersive free energy of the solid stationary phase is firstly determined by using a series of linear alkane liquids as molecular probes, and then the acid-base parameters are calculated from the dispersive parameters. However, for the calculation of surface dispersive free energy, generally, two different methods are used, which are Dorris-Gray method and Schultz method. In this paper, the results calculated from Dorris-Gray method and Schultz method are compared through calculating their ratio with their basic equations and parameters. It can be concluded that the dispersive parameters calculated with Dorris-Gray method will always be larger than the data calculated with Schultz method. When the measuring temperature increases, the ratio increases large. Compared with the parameters in solvents handbook, it seems that the traditional surface free energy parameters of n-alkanes listed in the papers using Schultz method are not enough accurate, which can be proved with a published IGC experimental result.     

Study of a core-shell type impact modifier by inverse gas chromatography

Inverse gas chromatography (IGC) has been used to study the Lewis acid-base properties of a technologically and commercially important core-shell type elastomer (MBS rubber). The parameters determined were the dispersive component of the surface tension, the surface free energy, the enthalpy and the entropy of adsorption of polar and apolar probes, the surface Lewis acidity constant (Ka), and the surface Lewis basicity constant (Kb). The results show that the MBS rubber is amphoteric but strongly Lewis basic. It is weakly Lewis acidic. The results are in accord with the analysis of the molecular structure of PMMA, the shell component of this impact modifier (IM). The interactivity of this elastomer with the remaining materials in multicomponent polymeric systems is expected to be strongly influenced by the particular surface energetic properties of the MBS rubber. The results presented would contribute to the interpretation, forecast and optimization of the adhesion properties and phase preferences shown by this impact modifier when incorporated in such complex polymeric systems as polymer blends and composites.     

Characterisation of cement pastes by inverse gas chromatography

Two cement pastes, commonly used in concrete formulations, were characterised by IGC at 35-80 degrees C before and after coating with an epoxy resin and a hardener. The cements are mixtures of hydrates in various proportions, such as calcium silicate hydrate (CaO-SiO2-H2O) and calcium hydroxide Ca(OH)2. Apolar and polar probes were used to determine the dispersive and acid-base characteristics of the cement pastes. These materials have high surface energy as judged from the dispersive contribution to the surface free energy (gamma(s)d) values lying in the 50-70 mJ/m2 range at 60-80 degrees C. Examination of the specific interactions permitted to show that the cement pastes are strongly amphoteric species with a substantial predominant Lewis basicity that is in line with the basic pH of their aqueous suspensions. Following coating with an epoxy resin (DGEBA) and a hardener (triethylene tetramine), the surface energy of the cements decreases substantially with the mass loading of the organic material. The surface thermodynamic properties were also correlated with the surface chemical composition as determined by X-ray photoelectron spectroscopy.     

An inverse gas chromatographic characterization of polypyrrole-coated poly(vinyl chloride) powder particles

Polypyrrole-coated poly(vinyl chloride) powder particles (PPy-PVC) were prepared by the in-situ chemical polymerization of pyrrole in aqueous solutions in the presence of PVC powder particles using the method of Ouyang and Chan [Polymer 39 (1998) 1857] and characterized by inverse gas chromatography (IGC). By employing n-alkane, 1-heptene, chloroform and tetrahydrofuran molecular probes, the dispersive and acid–base components of the surface energy of the composite materials were estimated at infinite dilution. The values of the dispersive contribution to the surface energy (γ_S^d), at 50 °C, range from 30.3 to 43.5 mJ/m² for the composites, which is much lower than the value of 83.2 mJ/m² obtained for para-toluene sulfonate-doped polypyrrole (PPyTS) bulk powder. This indicates that the injected molecules probe both polypyrrole and the underlying PVC, thus indicating that the conducting polymer is rather patchy at the surface of the insulating polymer substrate. This conclusion supports the previous results obtained by X-ray photoelectron spectroscopy (XPS) [19], indicating that both the coating PPyTS and the substrate PVC are detected by their elemental markers nitrogen and sulfur, and chlorine, respectively.