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本文研究了Si/SiO2、Si/Si–H基底与聚苯乙烯(PS)之间的界面相互作用对PS薄膜的玻璃化转变及相关力学性能的影响.结果显示,无论何种基底,PS薄膜的玻璃化转变温度(Tg)都随其厚度降低而降低.但相同厚度(<110 nm)下,以Si/Si–H为基底时PS薄膜的Tg比以Si/SiO2为基底的PS薄膜高.Si/SiO2表面PS薄膜Tg开始下降的临界厚度为110 nm,远高于以Si/Si–H为基底时的40 nm.对PS薄膜的膨胀系数和弹性模量进行研究,也得到相似的临界厚度.另外,与Si/SiO2基底相比,在Si/Si–H上的PS薄膜具有更低的膨胀系数以及较高弹性模量.可能原因是Si/Si–H与PS具有较强的相互作用,限制了该界面分子的运动能力,导致基底/PS界面效应对薄膜分子运动的影响力增强,造成该薄膜Tg的厚度依赖性下降,并呈现出相对较硬的力学特征.
In this paper, the influence of the interfacial interaction between Si / SiO2, Si / Si-H substrates and polystyrene (PS) on the glass transition and the related mechanical properties of PS films was investigated. (Tg) decreased with the decrease of its thickness, but the Tg of PS film with Si / Si-H as substrate was higher than that of Si film with Si / SiO2 as the base under the same thickness (<110 nm) . The critical thickness of PS film begins to decrease at 110 nm on Si / SiO2 surface, which is much higher than that at Si / Si-H of 40 nm. The study on the expansion coefficient and elastic modulus of PS film also shows similar In addition, PS thin films on Si / Si-H have lower coefficients of expansion and higher elastic modulus than Si / Si-H substrates.Possible reason is that Si / Si-H and PS have stronger Interaction, which limits the motility of the interfacial molecules. As a result, the influence of the substrate / PS interface on the molecular motion of the film is enhanced, resulting in a decrease in the thickness dependence of the film Tg and exhibiting relatively hard mechanical characteristics.