Silica-Polymer Nanocomposite for Transparent and Flexible Encapsulation Layer = 투명하고 유연한 봉지 막으로 활용 가능한 실리카-고분자 나노복합체

다국어 초록 (Multilingual Abstract)

With the rapid development of displays and electronic devices, people carry their own electronic devices. Therefore, it is very important to secure the stability and reliability of the devices. With such importance, encapsulation materials with high barrier to oxygen and water molecules gain a great attention to extend device shelf life. Oxygen and water molecules penetrated into a device cause serious problems such as active layer degradation and electode oxidation. Besides, hydrogen gas generated by the reduction of water at the electrode interface leads to delamination at the interface which results in device failure. Therefore, the development of encapsulation layer to protect device from moisture and oxygen is considered as one of the major issues in these days.
To overcome the disadvantages of traditional encapsulation approach, many types of encapsulation layer have been studied such as organic single layer, inorganic single layer, and inorganic/organic multi-layer. However, they also have their own disadvantages thus an alternative seemed necessary.
Herein, we fabricated SiO2 nanoparticles-dispersed polymer nanocomposite and characterized its property. Moreover, in order to verify its possibility as an encapsulation layer, we encapsulated a Blue LED (BLED) with the 20 wt% SiO2- poly(trimethylolpropane triacrylate) (PTPT) nanocomposite. The stability test was conducted at 60 ℃and 90 % RH condition to accelerate the degradation of barrier property.
To improve dispersibility of silica nanoparticles in trimethylolpropane triacrylate (TPT) matrix, the surface of silica nanoparticles is modified by 3-(methacryloyloxy)propyl trimethoxysilane (MPS). Modified SiO2 nanoparticles are mixed with TPT solution, and then SiO2-PTPT nanocomposite films are fabricated by UV irradiation of the solution.
All the films were highly transparent with over 98% transmittance in the visible region and noticeable difference was not observed in all the samples and they still maintained transmittance levels of over 98%. The WVTR values of PTPT and SiO2-PTPT with 5 and 20 wt% SiO2 were 213.3, 196.1, and 174.1 g/m2day, respectively. The WVTR decreased with increasing SiO2 nanoparticle contents of nanocomposites. We assume that SiO2 nanoparticles in polymer have two major roles: one is generating tortuous path, and the other is absorbing water molecules. Moreover, we verified the possibility of SiO2-PTPT nanocomposite as an encapsulation layer by electroluminescence test.

목차 (Table of Contents)

• Chapter 1. Introduction 1
• 1.1 Current Display and Electronic Device Issues 1
• 1.2 Necessity of Encapsulation Layer 4
• 1.3 Trends of Encapsulation Layer 6
• 1.4 Inorganic/Organic Nanocomposite 9
• Chapter 2. Experiment 14
• 2.1 Materials and Characterization 14
• 2.2 Synthesis and modification of SiO2 nanoparticles 16
• 2.3 Preparation SiO2-PTPT nanocomposites 18
• Chapter 3. Result and Discussion 20
• 3.1 TEM Characterization of SiO2 Nanoparticles 20
• 3.2 Study the surface of SiO2 Nanoparticles 22
• 3.3 Dispersibility of SiO2 in SiO2-PTPT Nanocomposite 25
• 3.4 TGA and DSC Measurements of SiO2-PTPT Nanocomposite 29
• 3.5 WVTR Test of SiO2-PTPT Nanocomposite Films 33
• 3.6 Transmittance of SiO2-PTPT Nanocomposite Films 40
• 3.7 Electroluminescence Test of SiO2-PTPT Nanocomposite as an Encapsulation Layer 43
• Chapter 4. Conclusion 47
• Reference 48
• 초록 (국문) 51