具電磁波遮蔽效應之奈米石墨烯/水性聚胺酯奈米複合材料之製備及其特性之研究

Preparation and Characterization of Graphene Nano Sheets/Waterborne Polyurethane Nanocomposite for Electromagnetic Interference Shielding

楊芷瑀(Chih-Yu Yang)

指導教授 ： 馬振基

國立清華大學/工學院/化學工程學系/碩士(2015年)

摘要

本研究旨在製備具有電磁波遮蔽效果之高分子複合材料，基材的部分是選用具有磺酸根系(Sulfonate functional groups)之水性聚胺酯(Waterbrone Polyurethane, WPU)高分子，並利用Solution mixing的方式，將奈米石墨烯片(Graphene Nano Sheets, GNS)混入WPU中，製備出具有電磁波遮蔽效果之高分子複合材料。
第一部分：利用Solution mixing的方式製備具有電磁波遮蔽效果之高分子複合材料，以WPU為基材，並以modified Hummers’ method製備氧化石墨烯(graphene oxide, GO)，再利用化學還原法以NaBH4將其還原成GNS。為了使GNS具有更良好的分散性，以free radical polymerization改質GNS，使[2-(Methacryloyloxy)ethyl]trimethyl ammonium chloride (AETAC)接枝於GNS表面；另一方面則是為避免GO在還原時產生堆疊，於是以free radical polymerization改質GO，將AETAC接枝於GO表面，即為FGO，再進一步將FGO還原為FRGO，以提升材料的導電性。並將GNS、FGNS及FRGO分別混入WPU基材中，製備GNS/WPU、FGNS/WPU及FRGO/WPU之複合材料
，並且將此三種複合材料進行EMI shielding effectiveness測試，測試結果顯示出FRGO與WPU有較良好之相容性，可形成較完整的導電通路，使得FRGO/WPU複合材料具有最佳的電磁波遮蔽效果，於頻率8.2-12.4 GHz下可達到17 dB。
第二部分：為了提升複合材料的導電度及電磁波遮蔽效果，本部分延續第一部分之結果，以FRGO作為複合材料之filler，並進一步將不同比例之金屬銀顆粒(silver nanoparticles, Ag NPs)沉積於FRGO材料表面，來提升材料的導電度，進而達到提升複合材料之電磁波遮蔽效果，並探討不同比例之金屬銀顆粒對複合材料的導電度及電磁波遮蔽效果之影響。本部分同樣利用Solution mixing的方式製備Ag@FRGO/WPU複合材料，並將此複合材料進行EMI shielding effectiveness測試，由測試結果可以得知，隨著金屬銀顆粒之沉積比例增加，Ag@FRGO/WPU複合材料的導電度及電磁波遮蔽效果也隨之提升，當金屬銀顆粒與FRGO比例為10：1時(10Ag@FRGO/WPU)，具有最佳的導電度可達25.5 S/cm，於頻率8.2-12.4 GHz下其電磁波遮蔽效果可達到及35 dB。

關鍵字

石墨烯 ； 水性聚胺酯 ； 電磁波遮蔽材料

並列摘要

The aim of this study is to prepare the electromagnetic interference shielding (EMI SE) polymer composite by two-dimentional Graphene Nano Sheets (GNS) and Waterborne Polyurethane (WPU) via solution mixing method. This study includes two parts.
In the first part, graphene oxide (GO) was prepared from graphite by modified Hummers’ method, and then was reduced to GNS by NaBH4. In order to improve the dispersion and to prevent the restacking and aggregations of GNS during reduction, [2-(Methacryloyloxy)-ethyl]- trimethyl ammonium chloride (AETAC) was grafted onto the GO and GNS surface by free radical polymerization to form FGO and FGNS. FGO was reduced to FRGO by chemical reduction with NaBH4. According to the results of analysis of XRD, XPS and TEM, it was confirmed that AETAC was grafted onto GO and GNS surface. A simple solution mixing method was used to prepare GNS/WPU, FGNS/WPU and FRGO/WPU composite with 1, 3, 5 and 10 wt% filler content. The electrical conductivity of GNS/WPU (FGNS/WPU and FRGO/WPU) composites was increased with the filler content. The results showed that the highest electrical conductivity of 2.07 S/cm and EMI shielding effectiveness (EMI SE) of approximately 17 dB in the frequency of 8.2–12.4 GHz (X-band) were obtained by the 10 wt% filler content of FRGO/WPU composite.
In the second part, in order to increase the electrical conductivity and EMI SE of composites, silver nanoparticles (Ag NPs) were deposited on
the FRGO surfaces to form Ag@FRGO. The different weight ratios of Ag NPs to FRGO were 1：1, 1：3, 1：5 and 1：10, which formed 1Ag@FRGO, 3Ag@FRGO, 5Ag@FRGO and 10Ag@FRGO. A simple solution mixing method was used to prepare Ag@FRGO/WPU composites with 10 wt% filler content and different weight ratios of Ag NPs to FRGO. Results showed that the electrical conductivity and EMI SE of Ag@FRGO/WPU composites were increased with the increasing weight ratio of Ag NPs to FRGO. The highest electrical conductivity and EMI SE of 10Ag@FRGO/WPU composite over the frequency of 8.2–12.4 GHz were improved to 25.5 S/cm and 35 dB, respectively.

參考文獻

[22] 工業技術研究院化學工業研究所. 導電性高分子專題調查報告. 1998年6月.

[24] 陳幹男. 水性PU樹脂之改質研究. CHEMISTRY. 2004;62:461~72.

[34] March J. Advanced Organic Chemistry. 1991.

[39] 陳素珍. 陰離子水性聚氨酯奈米複材之製備與研究. 中原大學化學研究所碩士學位論文. 2004.

[67] 吳至彧. 利用化學氣相沉積法合成數層石墨烯以及其透明導電薄膜之研究. 國立清華大學工程與系統科學系碩士論文. 2009.