新型高分子/氧化鐵奈米線磁性混成材料之合成與性質研究

Abstract

利用表面成長原子自由基轉移聚合法(surface-initiated atom transfer radical polymerization, surface-initiated ATRP)成功的合成出高分子/氧化鐵磁性奈米線。首先，使用共沉澱法合成Fe3O4 nanoparticles (Fe3O4 NPs)，再將Fe3O4 NP分散於強鹼水溶液中，經由水熱法即可合成出Fe3O4 nanowires (Fe3O4 NWs)，並且改變不同反應條件，如：反應時間、反應溫度、強鹼濃度、奈米粒子的濃度和填充度，利用TEM和SEM觀察產物的形態，X-ray 粉末繞射鑑定產物的結晶性。利用簡單的SN2化學反應成功的合成出一端帶有磷酸且另外一端可做為 ATRP起始劑的小分子-(2-bromo-2-methylproponate) octyl phosphonic aicd, P8CBr，並且藉由1H-NMR鑑定P8CBr的結構；將P8CBr中的磷酸吸附至Fe3O4 NWs的表面上形成P8CBr/Fe3O4磁性混成材料，並且利用Fourier Transform Infrared spectroscopy (FT-IR)分析。以P8CBr/Fe3O4當作起始劑並且將其分散於少量的DMF中，利用CuBr/PMDETA當作催化劑，在100oC時，將苯乙烯在氧化鐵的表面上進行聚合反應，即可以得到聚苯乙烯/氧化鐵(PS/iron oxide)的磁性混合材料，分別反應6小時和24小時，利用TEM觀察不同反應時間所得到的產物，並且利用Gel permeation chromatography(GPC)測定聚苯乙烯的分子量；藉由高速離心比較P8CBr/Fe3O4和PS/iron oxide的穩定性，最後，利用superconducting quantum interference device magnetometer(SQUID magnetometer)測量Fe3O4 NPs、Fe3O4 NWs和PS/iron oxide的磁場與磁化強度的關係。

In this study, we successfully synthesized polymer/iron oxide nanowires (NWs) by surface-initiated atom transfer radical polymerization (surface-initiated ATRP). Fe3O4 nanoparticles (NPs) were first prepared by co-precipitation method. As-prepared Fe3O4 NPs were then dispersed in NaOH aqueous solution and sealed into Teflon-lined stainless steel autoclaves. By changing reaction temperature、reaction time、concentration of NPs、concentration of NaOH and capacity, we could obtain different product which TEM and SEM were used to investigated the morphology and X-ray powder diffraction to characterize. Under apropos condition, Fe3O4 NWs were successfully synthesized. In order to grow polymer from the surface of Fe3O4 NWs by surface-initiated ATRP, we design a molecule-(2-bromo-2-methylproponate) octyl phosphonic aicd (P8CBr) which one end has phosphonic aicd and the other can be used as an ATRP initiator. P8CBr can therefore be linked to the surface of Fe3O4 nanowires via phosphonic acid which can be verified by Fourier Transform Infrared spectroscopy (FT-IR). P8CBr/Fe3O4 can be seen as an initiator and we use CuBr/PMDETA as a catalyst. Adding DMF as solvent is in order to improve the derpersibility of initiator in monomer (styrene). Polystyrene (PS) was then grown from the surface of iron oxide at 100oC. The reactions continued for 6 hr and 24 hr. The TEM were used to observe the morphology of product and GPC was used to obtain the number average molecule weight of grown PS. Besides, the stability of P8CBr/Fe3O4 and PS/iron oxide in chloroform was tested by centrifuge and compared by ultraviolet-visible (UV) absorption spectroscopy. The magnetic property of Fe3O4 NPs、Fe3O4 NWs and PS/iron oxide were measured by superconducting quantum interference device magnetometer (SQUID magnetometer).