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）。     

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。     

反相气相色谱表征可溶性聚酰亚胺的表面性质

采用反相气相色谱技术,将正己烷、正庚烷、正辛烷、正壬烷作为非极性分子探针,乙醚、丙酮、三氯甲烷作为极性分子探针在50℃、60℃、70℃和80℃条件下测定了可溶性聚酰亚胺HQDPA-DMMDA的表面色散自由能与表面Lewis酸碱性质.HQDPA-DMMDA在50℃、60℃、70℃和80℃的表面色散自由能分别为34.37、31.80、29.50和27.64 mJ/m2,自由能随温度的升高而线性降低.实验发现,HQDPA-DMMDA为弱的Lewis两性聚合物材料,其Lewis酸常数Ka为0.4115,碱常数Kb为0.5812.     

反气相色谱法表征聚合物表面性质的方法比较

以聚甲基丙烯酸甲酯-丙烯酸丁酯-苯乙烯基七环戊基多面齐聚倍半硅氧烷三元共聚物为模型聚合物,全面介绍了反气相色谱技术表征聚合物表面性质的方法,探讨了不同的计算方法对测定结果的影响。结果表明:Schultz方法和Dorris/Gray方法均可用于计算聚合物的表面能的色散分量γsD,但两者测得的γsD值存在一定的差异,且随温度的升高,差异逐渐增大,Dorris/Gray方法更适合于计算聚合物的γsD;而Sawyer、Schultz和Papirer 3种方法都能表征聚合物表面与极性探针的特殊相互作用以及聚合物表面的酸碱特征,其中以溶剂探针的沸点作参照点的Sawyer计算方法更具有简单、快捷的优点,更具有实用性。     

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。     

反相气相色谱法探究铜镁铝水滑石的表面性质

采用共沉淀法合成了Cu_xMg_3-xAl-LDHs (x＝0～3), 利用FTIR 及IGC 法(反相气相色谱法)对合成的样品进行测试和表征, 并结合计算机模拟的结果来探讨铜镁铝水滑石的表面性质. 结果表明, 随 Cu²⁺含量的增加, 铜镁铝水滑石表面吸附自由能及表面能色散组分增加, 稳定性下降, 这可能由于Cu²⁺本身具有的Jahn-Teller 畸变会很大程度地影响层板的稳定性, 导致含铜水滑石体系的稳定性降低; 随着Cu²⁺含量的增加, 水滑石表面碱性先减小后增大.     

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。     

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.     

Inverse gas chromatographic method for measuring the dispersive surface energy distribution for particulates

Inverse gas chromatography (IGC) is a widely used method for determining the dispersive component of the surface energy (gamma s (d)) of particulate and fibrous solids. Such measurements are normally conducted at very low solute concentrations (infinite dilution), and they result in a single numerical value of gamma s (d) for homogeneous materials which exhibit Henry's Law adsorption behavior. However, many real solid surfaces are heterogeneous and this may be demonstrated by the nonlinear isotherms obtained at low solute surface coverages resulting in reported gamma s (d) values which are not unique. This paper presents a new method for determining of gamma s (d) distributions as a function of the solute surface coverage using adsorption isosteres for an homologous series of hydrocarbon adsorbates. gamma s (d) distributions reported here were successfully determined using two different solid materials (glass beads and alumina particles) up to typical surface coverages of approximately 10% and clearly show significant variations in gamma s (d) with solute surface coverage. The effects of sample aging and pretreatment also exhibited clear differences in the gamma s (d) distributions obtained. gamma s (d) was determined using both the Dorris-Gray and Schultz methods, with the Dorris-Gray method exhibiting a much lower experimental error. It was established that the errors associated with this statistical measurement of surface energy were strongly dependent on the quality of the experimental data sets obtained. R (2) for the linearity of fit of the retention data to the Dorris-Gray gamma s (d) analysis was found to be a valid criterion for predicting the robustness of gamma s (d) distributions obtained. Detailed discussions of other critical experimental and analysis factors relevant to this methodology, as well as the reproducibility of gamma s (d) profiles are also presented. This paper establishes that IGC can be used for determining the gamma s (d) distributions of particulate solids and is demonstrated that this method is very useful way for studying the surface energy heterogeneity of complex particulate solids.     

硅胶自环己烷中吸附含氧芳香化合物的研究

测定了15℃和30℃时硅胶自环己烷中吸附苯甲醇、苯甲醚、苯甲醛和苯甲酸的吸附等温线,这些等温线皆可用Langmuir公式表示。利用Langmuir常数n_m^s和b值计算了吸附过程的△G⁰、△H⁰和△S⁰;四种化合物的△S⁰皆为正值。测定了在较大复盖度时红外光谱图上硅胶表面自由羟基峰的移动值△v_OH。结果表明△H⁰和△v_OH及△v_OH^1/2间有线性关系。文中对所得结果做了初步的解释。     

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.     

Inverse gas chromatography applications: A review

Inverse gas chromatography (IGC) is a versatile, powerful, sensitive and relatively fast technique for characterizing the physicochemical properties of materials. Due to its applicability in determining surface properties of solids in any form such as films, fibres and powders of both crystalline and amorphous structures, IGC became a popular technique for surface characterization, used extensively soon after its development. One of the most appealing features of IGC that led to its popularity among analytical scientists in early years was its similarity in principle to analytical gas chromatography (GC). The main aspect which distinguishes IGC experiments from conventional GC is the role of mobile and stationary phases. Contrary to conventional GC, the material under investigation is placed in the chromatographic column and a known probe vapour is used to provide information on the surface.     

Determination of the polar and total surface energy distributions of particulates by inverse gas chromatography

This Letter reports a technique of measuring polar surface energy distributions of lactose using inverse gas chromatography (IGC). The significance of this study is that the total surface energy distributions can now be characterized by combining the already known dispersive surface energy distribution with polar surface energy distribution determined in this study. The polar surface energy was calculated from the specific free energies for surface interactions with a monopolar basic probe, ethyl acetate, and a monopolar acidic probe, dichloromethane.     

New approach to characterise physicochemical properties of solid substrates by inverse gas chromatography at infinite dilution. I. Some new methods to determine the surface areas of some molecules adsorbed on solid surfaces

This study was divided into three different parts that tried to give a new contribution to determine and quantify more precisely the superficial properties of solid substrates (polymers and/or oxides) obtained by inverse gas chromatography (IGC) at infinite dilution. It criticised certain of the classical methods and relationships used to determine some physico-chemical properties of a solid and gave new methods and equations that can be more precise and more realistic. Part I developed some new methods to determine the surface areas of some molecules adsorbed on solids. A theoretical calculation of surface areas of molecules adsorbed on solid substrates was proposed by using some theoretical models. Two new methods to determine the surface areas of polar molecules were developed. The first one consists of the determination of surface areas by coupling two classical methods, the dynamic contact angle and IGC techniques. The second new and general method, using the IGC technique, assumes that the specific interactions between a polar molecule and a solid proposed by Papirer and Schultz are the same. A new equation was obtained to determine the surface areas of polar molecules.