以原子轉移自由基聚合反應製備二氧化矽/聚苯乙烯奈米複合材料與分析

Abstract

本論文以原子轉移自由基聚合反應(ATRP)應用在二氧化矽/聚苯乙烯奈米複合材料的製作並進行結構的鑑定與基本性質分析。為確定原子轉移自由基聚合的反應條件，首先使用氯甲苯作為起始劑，探討原子轉移自由基聚合反應其溫度、時間、與催化劑比例等變數，比較各條件下聚苯乙烯分子量與分子量分布的關係，由此找出最適化的原子轉移自由基聚合條件，用於奈米複合材料的製作。在製作二氧化矽/聚苯乙烯奈米複合材料上，本研究選用粒徑大小約11nm的二氧化矽奈米微粒，分別與 (3-chloropropyl)trimethoxysilane(CTMS)、4-(chloromethyl)phenyltrimethoxysilane( CPMS )進行表面起始劑改質。由固態29Si譜圖裡T2、T3 peaks的出現、元素分析內含碳比例與碳核磁共振圖譜都說明了二氧化矽奈米微粒表面接上了起始劑。再由表面起始劑改質後的二氧化矽奈米微粒與苯乙烯單體進行原子轉移自由基聚合， 製作二氧化矽/聚苯乙烯奈米複合材料。經由TEM、SEM看出二氧化矽顆粒尺寸的分布均勻，且觀察出二氧化矽奈米微粒外層皆披覆著聚苯乙烯高分子，粒子間的堆疊在局部區域裡略具規則性，二氧化矽粒子均勻的散佈在聚苯乙烯裡。本篇研究也觀察利用二氧化矽粒子尺寸分布與其表層聚苯乙烯分子量分布在此兩個效應下控制二氧化矽/聚苯乙烯奈米複合材料內部結構形態。

Atom transfer radical polymerization techniques have been introduced to polystyrene/nanosilica nanocomposite by the attachment of ATRP initiating groups to the particle surface in this study. Subsequent ATRP of styrene monomers yielded core particles with well-defined homopolymers tethered to a nanosilica initiator. The optimum molecular weight and distribution of polystyrene prepared from ATRP was investigated by varying the reaction temperature、time and catalyst. Nano-scaled(10~15nm) colloidal silica was first modified by CTMS and CPMS initiator respectively. From the T2、T3 peaks in 29Si spectrum, Elemet Analysis, 13C nuclear magnetic resonance spectrums, all data illustrate that the initiators was covalent bonded to the surface of nanosilica particles. The modified nanosilica was then used to prepare polystyrene/nanosilica nanocomposite by ATRP method . From the TEM and SEM images of the nanocomposite reveal the relative uniformity of particle sizes, as well as the regularity in the interparticle spacing. Nanosilica particles was well-distributed in the polystyrene. This paper also investigated two effects : nanosilica size distribution and the molecular weight distribution of the coated polystyrene, to control the structure of polystyrene/nanosilica nanocomposite.