苯乙烯－马来酸酐共聚物单分子膜的静、动态性质

对不同分子量的苯乙烯－马来酸酐共聚物（PSM）单分子膜的π－A等温线、微 分曲线进行了研究，讨论了PSM单分子膜成膜过程及分子量对膜相变的影响，并用 动态膜障振动法测定了PSM单分子膜的动态弹性，结果表明，分子链的相互作用（ 如卷曲和缠结）在膜的形成中起着重要的作用，并影响膜的静、动态性质，单分子 膜的动态弹性曲线有双峰，且前者比后者小，随分子量增大，膜的凝聚性、刚性和 稳定性都增强，动态弹性都增大；且分子链的相互作用对PSM单分子性质影响增大 ，压缩过程中单分子膜的相变更明显。     

十八胺单分子膜的研究

通过测定在纯水和CdCl2溶液亚相上十八胺单分子膜的平衡、循环π～A等温线及其动态弹性,发现在亚相中加入Cd2+可以使膜的液态相凝聚性增强,固态相凝聚性减弱.液态的单分子膜在两种亚相上有较好的可回复性,而在固态膜中则不然.这可归因于在水面上十八胺分子间可形成氢键,而在CdCl2水溶液亚相上的十八胺则与Cd2+发生配位,形成了多配位络合物,两种情况下十八胺分子在高膜压区都会发生稳定的聚集.静、动态弹性的比较表明,膜障的振动不利于十八胺分子与Cd2+间的配位作用.     

单分子膜的动态弹性

综述了单分子膜弹性研究的最新发现，详细介绍了单分子膜弹性的动态测定方法和硬脂酸、亚油酸等单分子膜弹性的研究结果，讨论了分子结构、亚相正离子、ｐＨ值以及聚合反应对单分子膜弹性的影响。     

花生酸与铈β-二酮络合物混合单分子膜的成膜特性

将铈β-二酮络合物(Ce(tmhd)4)的氯仿溶液与花生酸(AA)的氯仿溶液以不同摩尔比混合并铺展在纯水亚相上,得到其与AA的混合单分子膜.对混合单分子膜的成膜特性(π-A等温线和体系超额自由能)进行了探讨,发现混合单分子膜的超额自由能为负值,混合过程为热力学自发过程,且在配比为1∶ 2时其绝对值最大,体系最稳定,并进一步讨论了混合单分子膜可能的凝聚态结构.在配比为1∶ 2时,研究了混合单分子膜的静态弹性和动态弹性.     

空气/水界面单分子膜的弹性

空气／水界面单分子膜的弹性是与膜应用有关的一个重要力学性质。本文对最近十几年来空气／水界面单分子膜的弹性的研究情况进行了综述,着重介绍X射线衍射法（XRD）、动态振动测量法、表面光散射法（SLS）、电生毛细波衍射法（ECWD）等空气／水界面单分子膜弹性的测量技术。     

花生酸-钌有机螯合物Ru(phen)2 3+的单分子膜和LB膜中分子聚集行为的研究

以功能性的钌有机螯合物Ru(phen)2 3+作为亚相离子,花生酸在亚相表面上形成稳定的单分子膜.π-A等温线和动态弹性测量表明,此膜因花生酸与钌螯离子发生了静电相互作用而有更大的可压缩性,并在固态区发生了分子聚集.用垂直法成功地制备了嵌有Ru(phen)2 3+离子的超薄有序Y-型LB膜.光谱实验表明,所得LB膜是稳定、均匀的层状三明治结构,在层面内Ru(phen)23+与花生酸结合成相对稳定的分子基团并形成了J-聚体.     

花生酸-钌有机螯合物Ru(phen)_3~(2+)的单分子膜和LB膜中分子聚集行为的研究

以功能性的钌有机螯合物Ru(phen) 2 + 3 作为亚相离子 ,花生酸在亚相表面上形成稳定的单分子膜 .π A等温线和动态弹性测量表明 ,此膜因花生酸与钌螯离子发生了静电相互作用而有更大的可压缩性 ,并在固态区发生了分子聚集 .用垂直法成功地制备了嵌有Ru(phen) 2 + 3 离子的超薄有序Y 型LB膜 .光谱实验表明 ,所得LB膜是稳定、均匀的层状三明治结构 ,在层面内Ru(phen) 2 + 3 与花生酸结合成相对稳定的分子基团并形成了J 聚体     

胆固醇/两性霉素B混合单层膜相互作用的研究

两性霉素B (AmB)为多烯类抗真菌抗生素, 它的吸收过程与生物膜有密切联系. 选用生物膜中的重要分子胆固醇为代表, 通过Langmuir-Blodgett (LB)膜技术测得胆固醇/两性霉素B单层膜表面压力与平均分子面积(π-A)曲线, 定量分析了固定模压下的平均分子面积(A)、弹性模量(C_S^－1)、过量吉布斯自由能(ΔG_ex)等参量. 实验结果表明, 胆固醇/两性霉素B两组分物质的量比与膜压对单层膜的弹性、稳定性以及热力学特性有影响|通过单层膜相互作用参数α进一步佐证了组分间物质的量比和表面压力对混合单层膜稳定性、混合性以及分子间相互作用具有重要影响.     

聚苯乙烯分子链构象与其薄膜的玻璃化转变行为

本文利用椭偏仪研究了成膜方式对不同分子量聚苯乙烯(PS)超薄膜玻璃化转变行为的影响.发现PS超薄膜的玻璃化转变温度(Tg)随着厚度降低的幅度与其成膜方式、分子量有关.当PS膜低于一定厚度时,旋涂法制备的PS膜的Tg比相同厚度浇铸法制备的膜低,且二者Tg差值随着厚度的降低而增大.这二种膜Tg的差值和Tg发生偏离时膜的临界厚度随聚苯乙烯分子量的增加而增加.利用非辐射能量转移荧光光谱证实成膜方式主要是影响PS分子链在膜中的构象.旋涂法制备的PS膜相对于本体在近表面区域分子链的形变更大.分子量愈大,分子运动时内摩擦阻力愈大,近表面区域分子的残余应力愈大.由于强运动能力的活性层(空气/PS界面)对PS薄膜Tg的影响占主导,相同厚度下分子链愈伸展,残余应力越大,PS薄膜的Tg越低,导致成膜方式与分子量的影响也愈大.     

Langmuir单分子膜的动态稳定性:

应用KSV LB-5000型Langmuir膜天平的VISCOS模式,对硬脂酸和19,21-二炔廿二碳酸(DDA)单分子膜在有无亚相离子、不同目标膜压、不同膜障振动频率和不同温度下的动态稳定性作了研究.实验表明,单分子膜的目标膜压越低,膜障交变振动的频率越低,单分子膜越稳定,亚相中加有金属正离子对单分子膜的动态稳定性也有利.     

两亲性嵌段聚醚酯在空气-水界面上的Langmuir单分子膜

聚醚酯是一种新型弹性材料,目前已成为工业化产品[1].对这种嵌段聚醚酯的合成和弹性行为[2]、熔体的流变性能[3]、以及纤维在拉伸状态下的聚集态结构和分子运动[4]已有一些报道.     

Surface Dynamic Elasticity of Amphiphilic Block Copolymer Monolayers on a Water Surface

The methods of longitudinal and transverse surface waves and of oscillating barrier were used to measure a surface dynamic elasticity of the monolayers of poly(ethylene oxide) and polystyrene block copolymers spread on water within the frequency range of 0.007–520 Hz. At low surface concentrations, the properties of monolayers are determined by the poly(ethylene oxide) block. Upon further monolayer compression, the transition to the regime of polymer brush occurs when the surface dynamic elasticity increases dramatically. Change in the molecular weight of poly(ethylene oxide) block does not lead to the qualitative change in the dependence of surface properties on the degree of monolayer compression. Surface viscosity in the regime of brush significantly differs from the results of calculations made by Buzzaet al. [26]. Possible reasons for this difference are discussed.     

Controlling the stability and reversibility of micropillar assembly by surface chemistry

For many natural and synthetic self-assembled materials, adaptive behavior is central to their function, yet the design of such systems has mainly focused on the static form rather than the dynamic potential of the final structure. Here we show that, following the initial evaporation-induced assembly of micropillars determined by the balance between capillarity and elasticity, the stability and reversibility of the produced clusters are highly sensitive to the adhesion between the pillars, as determined by their surface chemistry and further regulated by added solvents. When the native surface of the epoxy pillars is masked by a thin gold layer and modified with monolayers terminated with various chemical functional groups, the resulting effect is a graded influence on the stability of cluster formation, ranging from fully disassembled clusters to an entire array of stable clusters. The observed assembly stabilization effect parallels the order of the strengths of the chemical bonds expected to form by the respective monolayer end groups: NH(2) ≈ OH < COOH < SH. For each functional group, the stability of the clusters can be further modified by varying the carbon chain length of the monolayer molecules and by introducing solvents into the clustered samples, allowing even finer tuning as well as temporal control of disassembly. Using these features together with microcontact printing, we demonstrate straightforward patterning of the microstructured surfaces with clusters that can be erased and regenerated at will by the addition of appropriate solvents. Subtle modifications to surface and solvent chemistry provide a simple way to tune the balance between adhesion and elasticity in real time, enabling structures to be designed for dynamic, responsive behavior.     

Rheology of poly(methyl methacrylate) Langmuir monolayers: percolation transition to a soft glasslike system

An experimental study of the equilibrium properties and of the surface rheology of Langmuir monolayers of poly(methyl methacrylate) (PMMA) at the air/water interface has been carried out as a function of polymer concentration (Γ) and molecular weight (M(w)). Dilational and shear complex elasticity moduli covering a frequency range from 10(-3) to 0.2 Hz have been discussed. It was found that the air∕water interface behaves as a poor solvent for PMMA monolayers, thus suggesting that the polymer coils take collapsed soft-disks (pancakes) shape at the interface. The equilibrium and dynamic results suggest a fluid-to-soft-glass transition as the polymer concentration increases above a critical packing fraction at constant temperature. This two-dimensional transition is in agreement with results previously discussed for the dilational rheology of poly(4-hydroxystyrene) [F. Monroy, F. Ortega, R. G. Rubio, H. Ritacco, and D. Langevin, J. Chem. Phys. 95, 056103 (2005)]. Furthermore, the Γ-dependence of the relaxation dynamics of the monolayers suggests that the gel state may be considered as a fragile soft glass.     

Effect of the addition of polyelectrolytes on monolayers of carboxybetaines

We have studied the effect of the addition of sodium poly(styrene sulfonate) polymers on the properties of monolayers formed by the adsorption of two carboxybetaines with different number of separation methylenes between their charged groups. Fluorescence and surface tension measurements indicate that above the critical aggregation concentration a surfactant-polymer complex of electrostatic origin is formed in bulk. The complexes have a negative charge that is repelled by the negative charge of the surfactant adsorbed at the interface; consequently, the monolayer seems to be exclusively formed by surfactant carboxybetaines. The high-frequency surface viscoelasticity of the monolayers was studied by surface dynamic light-scattering measurements. The behavior of the dilational elasticity and viscosity is explained by relaxation involving molecular reorientation within the adsorbed layer.     

Dynamics of Monolayer–Island Transitions in 2,7‐Dioctyl‐benzothienobenzthiophene Thin Films

The order in molecular monolayers is a crucial aspect for their technological application. However, the preparation of defined monolayers by spin‐coating is a challenge, since the involved processes are far from thermodynamic equilibrium. In the work reported herein, the dynamic formation of dioctyl‐benzothienobenzothiophene monolayers is explored as a function of temperature by using X‐ray scattering techniques and atomic force microscopy. Starting with a disordered monolayer after the spin‐coating process, post‐deposition self‐reassembly at room temperature transforms the initially amorphous layer into a well‐ordered bilayer structure with a molecular herringbone packing, whereas at elevated temperature the formation of crystalline islands occurs. At the temperature of the liquid‐crystalline crystal–smectic transition, rewetting of the surface follows resulting in a complete homogeneous monolayer. By subsequent controlled cooling to room temperature, cooling‐rate‐dependent kinetics is observed; at rapid cooling, a stable monolayer is preserved at room temperature, whereas slow cooling causes bilayer structures. Increasing the understanding and control of monolayer formation is of high relevance for achieving ordered functional monolayers with defined two‐dimensional packing, for future applications in the field of organic electronics.     

Adsorption of water-soluble polymers with surfactant character. Dilational viscoelasticity

A brief summary of dilational surface viscoelatic properties of spread and adsorbed surfactant polymer films at the air-water interface is reported. The viscoelastic moduli have been measured as a function of frequency and surface pressure. The combination of several techniques, oscillating drop and barrier experiments and electrocapillary waves (ECW), has allowed us to investigate a broad frequency range. The dynamic elasticity epsilon shows a slight change with frequency and a noticeable pressure dependence for both kinds of monolayers. In the spread films, elasticity increases steeply with surface pressure, and reaches a constant value before the polymer begins to dissolve into the bulk. On the other hand, the adsorbed films exhibit a pronounced elasticity maximum, followed by a considerable decay when a loose surface structure is formed. The position of the maximum depends on the polymer chemical composition and molecular weight. The results on the overlapping surface pressure range confirm the dynamic equivalence of spread and adsorbed monolayers. At low surface concentration, the agreement between static and dynamic elasticity is quite satisfactory, but the values diverge considerably at higher surface pressures. The loss modulus omegakappa decreases monotonically with increasing omega, becoming zero (it can even take apparent negative values) for the highest frequencies. The frequency dependence of the elasticity has been well described by the diffusive control model of Lucassen-van den Tempel (LVT). However, its predictions for omegakappa do not coincide with the experimental data. The differences between experimental and theoretical values increase at low frequencies.