以多體耗散粒子動力學研究星狀高分子定向自組裝於基材表面

Abstract

星狀高分子由於具有豐富的多樣性結構，能夠定向自組裝成多種型態以應用於奈米蝕刻。本研究利用多體耗散動力學研究ABC星狀高分薄膜於基材表面上之微結構與穩定性，並透過改變基材表面親和力以及高分子構型以探討其因素對於薄膜的影響。 在研究中，當高分子薄膜置於非選擇性之基材上，亦即基材對高分子各鏈段之粒子具相同之親和力。由模擬結果得知，不同的高分子構型會自組裝而成不同的結構，如層狀結構或是正多邊形鑲嵌等，且其圖形皆垂直於基材表面。當高分子薄膜置於選擇性之基材上，星狀高分子會因作用力設定的不同而使薄膜產生完全不同的微結構。接著在高分子薄膜置入一個乾孔以模擬當薄膜受外界干擾時的孔洞變化情形，並藉此判斷薄膜之穩定性。結果顯示其孔洞變化可以分為三個平衡狀態，（i）自我修復（ii）穩定孔洞以及（iii）成核擴張，影響薄膜穩定性的原因包括乾孔大小、薄膜微結構、基材親和力等因素。 以基材表面之作用力作為基礎，將高分子刷接枝於基材表面，並透過改變高分子刷之組成比例，以調節其表面對於高分子薄膜之親和性。結果發現當高分子刷各成分組成相同時，則其表面能再現非選擇性基材之親和力，使其高分子呈現垂直於基材表面之排列。當高分子刷各成分組成不一致時，則其表面能再現選擇性基材之親和力。

Due to the rich diversity of the architectures, miktoarm star polymers possess the ability of directed self-assembly into various morphologies which have potential applications for nanolithography. In this study, many-body dissipative particle dynamics is used to explore the microstructure and the stability of the thin film formed by the ABC miktoarm star terpolymers on substrate surfaces. The effects of attraction interaction between a polymer and the substrate and the conformation of miktoarm star polymers on the behavior of the thin film are also investigated. For a polymer melt spread on a nonselective substrate surface, different ordered structures such as lamellae and Archimedean-tiling patterns are discovered as the conformations of miktoarm star polymers varies. Polymer films on selective substrate surfaces can exhibit microstructures that are distinct from those formed on the nonselective substrate surface. In order to examine the stability of the polymer thin films, a dry hole is imposed on it. Three types of scenarios are identified, (i) self-healing, (ii) stable hole, and (iii) nucleation and growth. The outcome depends on the radius of the dry hole, the conformation of miktoarm star polymer, and the surface interaction. Finally, we also study the effect of the polymer brushes on the morphological behaviors of the polymer thin film . By altering the composition of the polymer brushes, it is possible to manipulate the surfaces to mimic the affinity of nonselective or selective substrates.