含軟鏈段之醣類嵌段共聚物之 合成、形態與拉伸式元件應用

Abstract

可拉伸電子產品吸引了人們對可穿戴電子產品，電子皮膚和生物醫學應用之廣泛研究興趣。我們對用於場效電晶體，記憶體，發光二極體，感應器和太陽能電池應用的可拉伸電子產品特別感興趣。其中，有機記憶體被認為是可拉伸信息設備中的基本元件。特別地，基於聚合物的存儲器件已經顯示出它們的應用優勢，因為其製造成本低，溶液加工性，柔韌性，高機械強度和良好的可擴展性。另一方面，通用記憶行為，包括易失性或非易失性數字存儲器，如動態隨機存取存儲器（DRAM），靜態隨機存取存儲器（SRAM）和一次寫入讀取（WORM）可以通過供體/受體特徵或聚合物活性層的奈米結構來控制。然而，據我們所知，尚未報導使用基於碳水化合物的聚合物用於電阻記憶應用的可拉伸電子聚合物。 在本論文的第一部分（第2章）中，我們發現基於新型碳水化合物 - 嵌段 - 聚異戊二烯（MH-b-PI）嵌段共聚物（包括WORM，Flash和DRAM）之記憶型行為可以很容易地控制通過自組裝奈米結構（垂直圓柱體，水平圓柱體和有序球體），其中MH和PI鏈段分別提供電荷俘獲和可拉伸功能。隨著柔性PI嵌段長度的增加，所設計的共聚物的拉伸性可以顯著提高至100％而不會形成裂縫。因此，使用MH-b-PI薄膜作為電荷儲存層的本質上可拉伸的電阻記憶體元件（PDMS / CNT / MH-b-PI薄膜/ Al）被成功製造並且使用MH-b-PI12.6k下100％應變表現出優異的ON / OFF電流比超過106（-1V讀取），穩定Vset約-2V。此外，耐久特性可在40％應變下保持超過500次循環。這項工作確立並代表了設計綠色生物材料和可拉伸記憶材料的新途徑。 在本論文的第二部分（第3章）中，合成了一系列新的本徵可拉伸嵌段共聚物（BCPs），它們由線性AB型，ABA型和由寡聚醣（MH）和柔性聚合物組成的星形結構（丙烯酸正丁酯（PBA）嵌段用於場效應晶體體記憶體。 BCP薄膜用作記憶體元件中的電荷俘獲層，其中BCP相分離成軟PBA矩陣中的有序MH區。 MH區塊用作電荷俘獲位點，而軟PBA基質提供可拉伸性。特別是，具有末端MH塊的ABA型和星形結構的BCP不僅表現出優異的記憶性能，而且形成物理交聯作用，賦予薄膜機械彈性，使得它們能夠承受100％的應變而不會形成裂縫。 即使當電荷俘獲層在50％應變下拉伸和釋放1000個循環時，其元件的電荷遷移率和存儲窗口幾乎是恆定的。這項工作突出了分子結構設計對用於可拉伸電子材料的BCP的重要性。

Stretchable electronics have attracted extensive research interest in wearable electronics, e-skin and biomedical applications. We are particularly interested in the stretchable electronics for the applications of transistors, memories, light-emitting diodes, sensors and solar cells. Among them, organic memory has been considered as basic elements in stretchable information devices. In particular, polymer-based memory devices have shown their advantages for applications because of the low fabrication cost, solution processability, flexibility, high mechanical strength and good scalability. On the other hand, the versatile memory behaviors, including volatile or non-volatile digital memories such as dynamic-random-access-memory (DRAM), static-random-access-memory (SRAM) and write-once-read-many-times (WORM), of polymer based devices could be manipulated through the donor/acceptor characteristics or the nanostructures of polymer active layer. However, to the best of our knowledge, stretchable electronic polymers of using carbohydrate-based polymers for the resistive memory application have not been reported yet. In the first part of this thesis (chapter 2), We discover that the memory-type behaviors of novel carbohydrate-block-polyisoprene (MH-b-PI) block copolymers based devices, including WORM, Flash and DRAM, can be easily controlled by the self-assembly nanostructures (vertical cylinder, horizontal cylinder and order-packed sphere), in which the MH and PI blocks respectively provide the charge-trapping and stretchable function. With increasing the flexible PI block length, the stretchability of the designed copolymers can be significantly improved up to 100% without forming cracks. Thus, intrinsically stretchable resistive memory devices (PDMS/CNTs/MH-b-PI thin film/Al) using the MH-b-PI thin film as an active layer is successfully fabricated and that using the MH-b-PI12.6k under 100% strain exhibits excellent an ON/OFF current ratio over 106 (reading at -1V) with stable Vset around -2 V. Furthermore, the endurance characteristics can be maintained over 500 cycles upon 40% strain. This work establishes and represents a novel avenue for the design of green carbohydrate-derivated and stretchable memory materials. In the second part of this thesis (Chapter 3), we synthesized a series of new intrinsically stretchable block copolymers (BCPs) in linear AB-type, ABA-type, and star-shaped architectures composed of oligosaccharide (MH) and flexible poly(n-butyl acrylate) (PBA) blocks for the application in field-effect transistor memory. The BCP thin films are used as the charge trapping layers in the memory devices where the BCPs phase separate into ordered MH microdomains in soft PBA matrices. The MH microdomain works as the charge-trapping sites while the soft PBA matrix provides a stretchability. In particular, the BCPs of the ABA-type and star-shaped architectures with the end MH blocks not only show superior memory performances but form physical networks that impart mechanical resilience to the thin films such that they can endure 100% strain without formation of cracks. The mobilities and the memory windows of the devices are nearly constant even when the charge trapping layers are stretched and released at 50% strain for 1000 cycles. This work highlights the importance of the molecular architectures on the BCPs intended for stretchable electronic materials.