利用液滴动态润湿行为研究界面效应对PS超薄膜玻璃化转变行为的影响

发布时间：2018-02-22 09:56

本文关键词： 动态润湿行为界面相互作用 PS超薄膜玻璃化转变　出处：《浙江理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：高分子薄膜的厚度随纳米器件尺寸的减小而不断降低。当薄膜厚度降低到高分子链的尺度后,聚合物薄膜的玻璃化转变行为会与本体发生偏离。界面效应是影响聚合物薄膜玻璃化转变温度偏离本体的主要因素之一。并且随着薄膜厚度的降低,界面效应的影响愈加显著。探究衡量界面相互作用强弱的物理参量能够进一步揭示界面效应影响聚合物薄膜玻璃化转变温度的本质。薄膜力学性能随温度变化,利用液滴动态润湿行为可以直接研究聚合物薄膜的玻璃化转变温度。本文通过改变PS链末端功能基团种类和PS分子量来调节聚合物薄膜与基底的界面相互作用,利用液滴动态润湿行为及椭圆偏振仪研究了界面效应对PS超薄膜玻璃化转变行为的影响。结果发现:(1)不同分子量端基化PS超薄膜在Si O2基底表面的Tjm均随薄膜厚度的降低而降低。但是薄膜Tjm降低程度以及Tjm开始偏离本体的临界厚度随端基种类和PS分子量的不同而发生变化。当分子量小于120 kg/mol时,相同厚度下Tjm的次序为:HO-PS-OHHOOC-PS-COOHH-PS-H;临界厚度的次序为:HO-PS-OHHOOC-PS-COOHH-PSH。并且相同厚度下分子量越小,HO-PS-OH和HOOC-PS-COOH薄膜的Tjm越高,临界厚度越小;而H-PS-H薄膜Tjm的厚度依赖性与分子量无关。当分子量大于120 kg/mol时,不同端基化PS超薄膜Tjm的厚度依赖性基本相同。基底与PS链末端功能基团间的界面相互作用差异是导致PS超薄膜具有不同玻璃化转变行为的主要原因。利用椭圆偏振仪测得的结果与液滴动态润湿行为的结果非常相似。因此,液滴动态润湿行为测量聚合物薄膜玻璃化转变温度的方法是可行的且具有普适性的。(2)基底表面PS薄膜的吸附层厚度(Ra)与PS回转半径(Rg)的比值可作为衡量界面效应影响聚合物薄膜玻璃化转变温度的主要参数之一。PS超薄膜Tjm的降低值(ΔTjm)随Ra/Rg值的增大而线性增大;同时,Tjm开始偏离本体的临界厚度随Ra/Rg值的增加而线性减小。本论文首次发现了Ra/Rg与聚合物薄膜玻璃化转变温度的关系,并且根据Ra/Rg值可以估测与基底间具有不同界面相互作用的聚合物薄膜的玻璃化转变温度。(3)界面效应也对液滴在聚合物薄膜表面的stick-slip行为产生影响。不同分子量端基化PS超薄膜的最大跳跃角(Δθmax)随薄膜厚度变化的斜率Kθ以及最大跳跃角(△θmax)随wetting ridge高度变化的斜率Kw均随Ra/Rg值的增大而线性增大。表明界面相互作用越强,PS超薄膜的最大跳跃角(Δθmax)和wetting ridge高度随薄膜厚度增大得越快。
[Abstract]:The thickness of the polymer film decreases with the decrease of the size of the nanodevices, and when the thickness of the film decreases to the scale of the polymer chain, The glass transition behavior of polymer films will deviate from the bulk, and the interfacial effect is one of the main factors that influence the transition temperature of polymer films deviating from the bulk, and with the decrease of film thickness, The influence of interfacial effect is becoming more and more obvious. The physical parameters which measure the strength of interfacial interaction can further reveal the nature of interfacial effects on the glass transition temperature of polymer films. The mechanical properties of the films vary with temperature. The glass transition temperature of polymer films can be studied directly by using the dynamic wetting behavior of droplets. In this paper, the interface interaction between polymer films and substrate is regulated by changing the type of functional groups at the end of PS chain and the molecular weight of PS. The effect of interfacial effect on glass transition behavior of PS ultrathin films was investigated by using droplet dynamic wetting behavior and ellipsometry. The results show that Tjm of PS ultrathin films with different molecular weights on the surface of Sio 2 substrates all depend on the thickness of the films. However, the decrease of Tjm and the critical thickness of Tjm begin to vary with the type of terminal group and the molecular weight of PS. When the molecular weight of the film is less than 120 kg/mol, The order of Tjm at the same thickness is: HO-PS-OHHOOC-PS-COOHH-PS-Hand the critical thickness is in the order of: HO-PS-OHHOC-PS-COOHH-PSH. The smaller the molecular weight of HO-PS-OH and the higher the critical thickness of HOOC-PS-COOH films, the lower the critical thickness of HO-PS-OH and HOOC-PS-COOH films at the same thickness, while the thickness dependence of H-PS-H film Tjm is independent of the molecular weight. When the molecular weight is more than 120 kg/mol, the critical thickness of HO-PS-OH and HOOC-PS-COOH films is lower. The thickness dependence of PS ultrathin film Tjm with different terminal groups is basically the same. The difference of interface interaction between the substrate and the functional groups at the end of PS chain is the main reason for the different glass transition behavior of PS ultrathin film. The ellipse is used to make use of the ellipse. The results measured by polarimeter are very similar to those of droplet dynamic wetting behavior. The method of measuring the glass transition temperature of polymer films by dynamic wetting behavior of droplets is feasible and universal. The ratio of the thickness of adsorption layer of PS film on the substrate surface Ra) to the radius of rotation of PS can be used as a measure of interfacial effect. The decreasing value of Tjm (螖 TJM) of PS ultrathin film increases linearly with the increase of Ra/Rg value. At the same time, the critical thickness of Tjm begins to deviate from the bulk and decreases linearly with the increase of Ra/Rg. In this paper, the relationship between Ra/Rg and glass transition temperature of polymer films is first found. Based on the Ra/Rg value, the glass transition temperature of polymer films with different interfacial interactions with the substrate can be estimated. The interface effect also affects the stick-slip behavior of droplets on the surface of polymer films. The slope K 胃 of the maximum jump angle (螖 max胃) with the thickness of the film and the slope K w of the maximum jump angle with the wetting ridge height increase linearly with the increase of the Ra/Rg value. It is shown that the stronger the interfacial interaction is, the stronger the interface interaction is. The maximum jump angle (螖胃 max) and the height of wetting ridge increase faster with the film thickness.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2;TQ317

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