以異質吸引法製備高分子/碳黑複合顆粒及其性質與應用研究

Abstract

本研究是利用異質吸引法製備微米級高分子/碳黑複合顆粒和其形態的探討。系統架構是利用分散聚合法先製備窄分佈且表面具有正電的高分子乳膠顆粒，接著使用矽烷氧化物對表面帶有負電的市售碳黑進行表面性質修飾，最後將高分子乳膠顆粒與碳黑顆粒在水中混合，藉由調控pH值使得兩者互相吸引，並加高反應溫度至乳膠顆粒玻璃轉移溫度以上，讓其表面稍微軟化，形成穩定的高分子/碳黑微米級複合顆粒。 實驗的第一部分討論在不同的反應條件下，以分散聚合製備出的高分子乳膠顆粒其粒徑均勻程度、界面電位大小與等電點的差異以及玻璃轉移溫度的高低。首先以動態光散射粒徑電位分析儀檢測顆粒之介面電位，由pH值與介面電位的關係找出高分子顆粒的等電點，再使用掃描式電子顯微鏡觀察粒徑大小，接著使用差式掃描熱量分析儀檢測其玻璃轉移溫度。 實驗的第二部分是以溶膠凝膠法對市售碳黑顆粒進行表面改質，藉由改質條件和矽烷氧化物種類的改變，研究改質後其表面性質的差異。先以動態光散射粒徑電位分析儀檢測碳黑顆粒分散在水中的粒徑分佈，還有隨著pH值改變的電位變化，接著以熱重示差同步掃描分析儀檢測改質在碳黑表面的量，並以紅外線光譜儀、固態矽譜核磁共振儀檢驗改質結果。 實驗最後的部分為高分子顆粒和碳黑顆粒的異質吸引實驗，藉由調控適當的pH值與加熱溫度，使高分子與碳黑藉靜電吸引力互相吸引，同時加熱讓高分子表面軟化，形成穩定的複合顆粒。以低轉速離心純化反應後的複合顆粒，同時洗去殘餘碳黑與分散劑，接著用掃描式電子顯微鏡觀察顆粒表面的吸附狀況，再以熱重示差同步掃描分析儀檢測吸附的量，最後將複合顆粒以樹酯包埋，用超薄切片機切片後，以穿透式電子顯微鏡進行觀察。

In this study, we synthesized micron-sized carbon black/polymer composites by heterocoagulation. First of all, we fabricated the polymeric latex with narrow size distribution and positive surface charge. Secondly, carbon black surface modification with silane coupling agent by sol-gel process had been achieved. In the last part, polymeric latex and surface-modified carbon black were mixed in water then we adjusted the pH value of the solution to a certain level and heated above the glass transition temperature of the polymeric latex to form carbon black/polymer composites. In the first part, we studied some experimental parameters that may affect the polydispersity, zeta potential, isoelectric point or Tg of the polymeric latex fabricated by dispersion polymerization. Dynamic light scattering zetasizer had been used to measure the zeta potential of the polymeric latex. We also used scanning electron microscopy(SEM) to measure the size of the latex particles. Glass transition temperature was measured by differential scanning calorimeter. In the second part, carbon black surface modification with various functional group on the silane coupling agents via sol-gel process had been studied. The size and its distribution of the modified carbon black were measured by dynamic light scattering and thermogravimetric analysis, then Fourier transform infrared spectrometer was used to confirm the results. In the last part, we fabricated the carbon black/polymer composites via heterocoagulation method. Appropriate pH values were controlled to achieve good heterocoagulation results. By heating up the polymeric latex to above its Tg, the surface of polymeric latex will become soft to form the stable composites with heterocoagulated carbon black on their surfaces. The composites were purified with centrifuge and the amount of the heterocoagulated carbon black was tested by thermogravimetric analysis. The morphologies of the cross section of the composites were observed via transmitting electron microscope ultra-thin sectioning technique.