本文選題：納米纖維素 + 熒光納米晶體�。� 參考：《上海大學(xué)》2015年碩士論文

【摘要】：基于天然生物質(zhì)的納米纖維素(NFC),由于具有低密度特性、高長徑比、高機械強度、晶體高度有序等結(jié)構(gòu)性能,以及優(yōu)良的生物相容性和生物可降解性,有望取代石油基聚合物材料應(yīng)用于透明薄膜,柔性電子,生物醫(yī)藥、組裝工程等領(lǐng)域。目前,關(guān)于納米纖維素的制備技術(shù)和表面改性等方面的研究成為國內(nèi)外研究的熱點。因此,如何優(yōu)化納米纖維素精細分離、形貌結(jié)構(gòu)以及表面基團控制,與功能材料形成有效復(fù)合接枝成為制備新型纖維素基納米復(fù)合材料的關(guān)鍵。本文分別采用酸水解法和高壓均質(zhì)法從多種植物中提取制備納米纖維素,通過不同的改性或組裝方式,構(gòu)筑了基于納米纖維素的熒光納米復(fù)合材料。1)以蒜皮、麻纖維、海帶、滸苔為原料,通過酸水解法制備得到納米纖維素,研究了酸水解過程中不同處理階段樣品形貌及晶型變化規(guī)律,并與高壓均質(zhì)法進行了對比分析。酸水解制得的納米纖維素形貌呈纖維狀,直徑為10~50 nm,長度達幾微米,長徑比大于50,結(jié)晶度較高,其中蒜皮的結(jié)晶度可達74.2%;酸水解法得到的納米纖維素具有更好的熱穩(wěn)定性,而高壓均質(zhì)法制得的納米纖維素具有更高的長徑比;采用TEMPO氧化法對納米纖維素表面羥基羧基化改性,研究表明TEMPO氧化改性在引入羧基的能夠同時保持納米纖維素的形貌結(jié)構(gòu)穩(wěn)定性。2)以冬瓜汁為原料,通過一步水熱法制備了氮摻雜的熒光碳點(CDs),與表面羧基化的NFC復(fù)合接枝,制得NFC/CDs納米復(fù)合材料。熒光CDs的直徑為4.5~5 nm,表面存在大量羥基、羧基以及含氮官能團,當(dāng)激發(fā)波長為360 nm時,CDs的熒光強度達到峰值,對應(yīng)的發(fā)射波長為448 nm,呈現(xiàn)藍色熒光,對hep G2細胞無毒害作用,具有良好的細胞相容性及細胞成像特性。NFC/CDs納米復(fù)合材料用于重金屬離子Cu2+的檢測吸附,經(jīng)冷凍干燥后的NFC/CDs納米復(fù)合材料具有網(wǎng)狀多孔結(jié)構(gòu),有利于Cu2+的大面積快速吸附,檢測濃度極限可達1μM。3)對Na YF4:Yb,Er(UCNPs)進行表面環(huán)氧化改性,實現(xiàn)UCNPs與NFC表面羥基的組裝接枝,經(jīng)壓濾擠出快速脫水制得具有優(yōu)異發(fā)光性能的NFC/UCNPs復(fù)合納米紙。該熒光納米紙復(fù)合兼具NFC納米紙的透光性和UCNPs的熒光性能,其透光率與980 nm激光激發(fā)下的熒光強度受UCNPs含量影響,熒光強度隨UCNPs增加而增強,而透光率降低,納米紙中NFC/UCNPs構(gòu)成的異質(zhì)互穿網(wǎng)狀結(jié)構(gòu)有利于熒光納米紙的光學(xué)穩(wěn)定性。
[Abstract]:Because of its low density, high aspect ratio, high mechanical strength, highly ordered crystal structure, and excellent biocompatibility and biodegradability, the nano-cellulose based on natural biomass has good biocompatibility and biodegradability. It is expected to replace petroleum-based polymer materials in transparent film, flexible electronics, biomedicine, assembly engineering and so on. At present, the research on preparation technology and surface modification of nano-cellulose has become a hot spot at home and abroad. Therefore, how to optimize the fine separation of nano-cellulose, the control of morphology and surface group, and the effective composite grafting with functional materials become the key to the preparation of new cellulosic nanocomposites. Nanocellulose was prepared by acid hydrolysis method and high pressure homogenization method, respectively. The fluorescent nanocomposites based on nano-cellulose were prepared by different modification or assembly methods, such as garlic peel, hemp fiber, kelp, etc. Nanocellulose was prepared by acid hydrolysis method from Enteromorpha enteromorpha. The morphology and crystal morphology of samples in different stages of acid hydrolysis were studied and compared with high pressure homogenization method. The morphology of the nanocellulose prepared by acid hydrolysis is fibrous, the diameter is 10 ~ 50 nm, the length is several microns, the aspect ratio is more than 50, and the crystallinity of garlic peel can reach 74.2, and the nanocellulose obtained by acid hydrolysis has better thermal stability. The nanocellulose prepared by high pressure homogenization method has a higher aspect ratio. The surface hydroxyl carboxylation of nano-cellulose was modified by TEMPO oxidation method. The results showed that when carboxyl group was introduced in TEMPO oxidation modification, the morphology and structure stability of nanocellulose could be maintained at the same time. 2) the nitrogen-doped fluorescent carbon dot (NFC) was prepared by one step hydrothermal method, which was used as raw material to prepare nitrogen-doped carboxylated NFC, which was grafted with carboxylated NFC on the surface. NFC/CDs nanocomposites were prepared. The diameter of fluorescent CDs is 4.5 nm, and there are a large number of hydroxyl groups, carboxyl groups and nitrogen-containing functional groups on the surface. When the excitation wavelength is 360nm, the fluorescence intensity of hep / CDs reaches the peak and the corresponding emission wavelength is 448nm, which shows blue fluorescence and has no toxic effect on hep G2 cells. NFC / CDs nanocomposites have good cellular compatibility and cell imaging properties. NFC / CDs nanocomposites are used for the detection and adsorption of heavy metal ions Cu2. The freeze-dried NFC/CDs nanocomposites have reticular porous structure, which is conducive to the rapid adsorption of Cu2 in a large area. The limit of concentration is 1 渭 M. 3) the surface of NaYF4: YbPs is modified by epoxidation. The NFC/UCNPs composite nanocrystals with excellent luminescent properties are prepared by pressure-filtration extrusion and rapid dehydration after the assembly and grafting of UCNPs and NFC surface hydroxyl groups. The fluorescent nano-paper has both the transmittance of NFC nano-paper and the fluorescence property of UCNPs. Its transmittance and fluorescence intensity excited by 980nm laser are affected by the content of UCNPs. The fluorescence intensity increases with the increase of UCNPs, but the transmittance decreases. The heterogeneous interpenetrating network of NFC/UCNPs in nanocrystalline paper is beneficial to the optical stability of fluorescent nanocrystalline paper.
【學(xué)位授予單位】：上海大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1;TB33

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