規則樹枝狀高分子界面活性劑分散氧化石墨烯與成核奈米銀粒子應用於表面拉曼增強效應

Abstract

由MDI合成具有反應選擇性的IDD後進一步合成一系列poly(urea/malonamide)直線型與透過收斂法合成樹枝狀陽離子界面活性劑衍生物，之後利用electrostatic interaction與氧化石墨接枝形成複合材料，使用TGA分析其接枝率，發現由於DG-2.5分子較大故有較大的立體障礙使得接枝率最低，並將奈米銀製備在poly(urea/malonamide)與氧化石墨複合材料的羰基官能基上，以UV-Vis以及TEM觀察奈米銀的生成和其附著情形，由TEM圖得知DG-2.5對於奈米銀的分佈和大小控制最好，因為DG-2.5有較多的官能基能穩定奈米銀的大小，相反的直線型的多呈現大小不一甚至聚集的情況，接著將材料取出以breath figure法和直接揮發製成蜂窩狀孔洞膜與平膜後發現只有DG-2.5與DG-1.5有機會形成蜂窩狀孔洞，之後滴上表面增強拉曼效應的待測物R6G，比較不同製程與不同代數以及直線型與樹枝狀結構之間的效應差別，得出DG-2.5為最佳的結果，並討論得出其它組別因為奈米銀成長的大小和分佈不一以及在成膜時較難以或無法形成孔洞，使得加成效應不如DG-2.5 此研究有別於過往一般界面活性劑以及表面增強拉曼效應的應用，在成蜂窩狀孔洞膜時直接分散了奈米銀粒子在膜當中，而不是先成膜再利用化學吸附，因此使得內外都能有奈米銀均勻的分佈，並且導入了氧化石墨增加了一定程度的表面增強拉曼效應，同時也使得所製成的膜能夠承受拉曼測量時的入射光，為首次有研究將界面活性劑與氧化石墨之複合材料應用於表面增強拉曼效應。

A series of linear type and dentritic type poly (urea/malonamide) cationic surfactants synthesized from IDD were successfully prepared as evidenced by NMR. Then, cationic surfactants were chosen to electrostatically adsorb on the negatively charged graphene oxide (GO) to form composites and the content of surfactant can be roughly estimated from TGA results. And DG-2.5 shows the lowest content becasuse DG-2.5 molecules are larger than other derivatives and the steric hindrance effect occurs. With carbonyl group on the poly (urea/malonamide) derivatives, silver nanoparticles can be prepared on the surfactants/GO composties to form the final products and as evidenced by UV-Vis and TEM. Then, the surface-enhanced Raman scattering (SERS) films can be obtained via breath figure process, but only DG-2.5 and DG-1.5 can form honeycomb-like films. Results show that surface enhancement factors of honeycomb-like substrates are much higher than that of flat-film substrates and DG-2.5 shows the highest enhancement factor >105 because DG-2.5 has the most carbonyl groups on the molucules. Consequetly, the SERS films have been successfully obtained and this work shows the potential of application of surfactants/GO on SERS effect.