速效增益及調控硬－柔嵌段共聚物之自組裝行為

Abstract

硬－柔嵌段共聚物（rod-coil block copolymers）因有著深厚的應用潛力而受到重視，特別是奈米微影技術及可撓曲性光電材料等領域。藉由調控鏈段間的作用力強度，我們可以得到豐富多樣的奈米尺度結構。然而，在過去的研究中，我們需要改變材料的化學結構或是降低聚合度才得以有效的調控作用力的強度，但這卻會降低材料在實際應用的表現。同時，硬－柔嵌段共聚物的擴散相當地糟，特別是有著強硬－柔鏈段作用力的導電高分子。如欲付諸實務應用，關鍵在於如何有效地得到多樣的有序奈米結構卻不改變高分子化學結構。在本研究中，我們發展了一套方法將硬－柔嵌段共聚物快速有效地形成高度有序的奈米結構。經由在熱退火的階段加入一高沸點的添加劑，硬－柔嵌段共聚物得以在低溫、短時間內輕易的達到熱平衡及高度有序結構。這有效的增益是源自於添加劑使得鏈段遷移能力的增加，同時抑制了硬－硬鏈段作用力以及硬－柔鏈段作用力。這個方法也適用於不同的添加劑，不同體積分率的共聚物，以及多樣的硬－柔嵌段共聚物系統。添加劑對高分子的溶解度，高分子的聚合度，以及作用力間的競爭等是調控材料型態的重要因素。重要的是，這個方法得以在製程中將添加劑完全除去，材料原始的功能性得已被保留而不會破壞原本的奈米結構。這個新穎的方法是基於動力學增益的熱力學平衡。由於製程中並沒有改變高分子的化學結構，表示我們得以將其適當地設計並使用於多樣的嵌段共聚物應用中。

Rod-coil block copolymer (BCP) is one of the most promising materials for potential applications in nanolithography and flexible optoelectronics. With adjustable rod-rod interaction and rod-coil interaction, various nanoscale morphologies are achievable. However, previous works have intentionally suppressed rod-rod interaction and/or rod-coil interaction through modifying the chemical structures or reducing the degree of polymerization, which may deteriorate the performance in actual applications. Also, rod-coil BCPs are notorious for their poor diffusion kinetics, especially for conducting polymer with strong rod-coil interaction. How to achieve versatile ordered nanostructure efficiently without changing the chemical structure of BCPs is the key for the success of practical applications. Herein, we report a facile approach to process rod-coil BCPs into highly order nanostructure. By introducing a high boiling point additive into the rod-coil BCPs during the thermal annealing process, their thermodynamic equilibrium and highly ordered structures can be easily achieved with lower temperature and shorter time. The improvement is attributed to enhanced chain mobility, reduced rod-rod interaction and decreased rod-coil interaction from the additive. The method is confirmed to be relevant to various additives, different compositions and types of rod-coil systems. The determining factors for properly tuning the morphology and improving the ordering are the solubility of additives, the molecular weight of polymers, and the competition between rod-rod interaction and rod-coil interaction in BCPs. Importantly, in this process, the additive is totally removed during the annealing process. The original functionality of BCPs is retained without changing already formed nanostructures. This novel method is based on kinetically enhanced thermodynamic equilibrium. It is free from the modification on polymer structure, indicating a wide variety of desired polymer functionality can be designed into BCPs for specific applications.