【作者】 杨旭东；

【导师】 林权；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2014， 博士

【摘要】 刺激响应性聚合物是具有根据环境的变化而改变自身的物理或者化学性质的一类功能性聚合物。最近几年，响应性聚合物微观体系由于具有尺寸小，对外界环境刺激响应快速的特点而受到研究人员的广泛关注，在药物缓释、疾病诊断、组织工程、智能光学材料、生物传感与分离、微电子器件、涂料和纺织业等领域都有着广泛的应用。在目前所报道的关于响应性聚合物材料的研究工作中，基于温度响应性聚合物聚(N-异丙基丙烯酰胺)(PNIPAM)及其共聚物所构筑的响应性微观体系的研究备受关注，成为一个研究热点。荧光检测作为一种响应快速、高灵敏、简单方便的分析技术而被广泛地用于物质检测、分子识别、生物标记、细胞成像等领域，逐渐成为化学和生物学科领域重要的检测手段。而将具有聚集诱导荧光增强(AIE)性质的荧光分子和荧光碳量子点引入到响应性聚合物中，构筑响应性聚合物微观体系并应用于检测、识别、成像等方面的研究，无论从基础研究还是应用价值，都是非常有意义的探索。在论文的第二章中，我们设计构筑具有pH和温度双重智能响应的微观体系，通过乳液聚合两步法制备以聚苯乙烯为核，PNIPAM-PAA为壳的纳米微球，分别在微球的内核和壳层组装稀土配合物和正电荷的AIE型荧光分子四苯基乙烯衍生物(d-TPE)，获得双荧光发射功能的响应性纳米微球。由于d-TPE分子与纳米微球作用，聚合物链段有效地限制了d-TPE分子的运动，导致d-TPE的荧光增强百倍以上，表现出优异的聚集诱导荧光增强(AIE)性质。在温度响应方面，随着环境温度的升高，纳米微球核层稀土配合物和壳层d-TPE分子的荧光强度同时逐渐下降，并在较宽的温度范围内(10-80℃)呈现线性可控变化。pH响应方面，由于壳层引入了pH响应性的聚合物聚丙烯酸(PAA),所以复合在壳层的d-TPE分子与聚合物的作用受到环境pH的调控，而组装在核内的稀土配合物的荧光性质不受pH的影响，保持荧光性质不变。由于微球核内和壳层的荧光性质对pH的不同响应性，聚合物纳米微球在酸性到碱性的不同pH值条件下呈现红色到紫色的不同荧光颜色，获得pH智能响应特性。由于纳米微球对温度和pH展现不同的荧光响应性质，使其在微观荧光纳米温度计、肿瘤细胞和组织检测、药物缓释等领域具有广阔的应用前景。论文的第三章，为了扩展对响应性聚合物微观体系的研究，提高材料的生物相容性和细胞靶向性，我们设计制备具有生物靶向性的纳米微粒。以生物分子叶酸(FA)和尿素(Urea)为原料，采用简单的微波辅助加热方法一步合成了对特异癌细胞具有选择性成像的荧光碳量子点，产物生物毒性低、荧光量子产率高、粒子尺寸小、尺寸均一，特定癌细胞靶向功能，可大量制备等优点，可以作为癌症的诊断和治疗的荧光显像材料来使用。进一步，我们将具有顺磁性的稀土钆离子[Gd(III)]通过与羧基的配位作用，实现与碳量子点的复合，所制备的碳点不仅具有荧光功能还具有顺磁性，可以应用于荧光和磁性双通道生物成像。在论文的第四章中，我们将响应性聚合物制成器件以扩展其在现实中的应用。首先，我们设计器件的温度响应特性，通过原子转移自由基聚合(ATRP)方法在石英基底上制备了温度响应性的p(NIPAM-co-AAc)聚合物分子刷薄膜，然后将d-TPE分子组装在分子刷上，得到荧光温度智能响应性的聚合物分子刷薄膜器件[d-TPE/p(NIPAM-co-AAc)],在2-70℃范围内，其荧光强度随环境温度升降具有线性可逆往复的变化规律。进一步，我们还研究了器件在检测方面的应用，实现了d-TPE/p(NIPAM-co-AAc)分子刷对铬酸根离子(CrO42-)的特异性响应，扩展了响应性聚合物器件在离子检测、环境监测等方面的应用。此外，我们采用ATRP方法，两步法合成了带负电荷的聚丙烯酸(PAAc)分子刷薄膜，接着，组装上d-TPE分子，制备荧光性d-TPE/PAAc分子刷薄膜器件，利用其与爆炸物TNT强相互作用，导致d-TPE/PAAc分子刷的荧光发生淬灭，可以实现该聚合物微观器件对TNT的超灵敏检测，检测限最高可达0.1ppb，远低于美国环保部门对饮用水的要求(1ppb)。这种响应性荧光分子刷薄膜器件结构为TNT检测提供了一种新型、方便、灵敏的检测方法，拓展其在爆炸物检测、环境监测、食品安全、实验分析等领域的应用。更多还原

【Abstract】 Stimuli-responsive materials are capable of exhibiting reversible or irreversiblechanges in physical properties and/or chemical structures to small changes inexternal environment. They can adapt to surrounding environments, regulatetransport of ions and molecules, change wettability and adhesion of different specieson external stimuli, or convert chemical and biochemical signals into optical,electrical, thermal and mechanical signals, and vice versa. In the recent studies, theresponsive polymer micro-system attracts extensive interests and has become aresearch highlight. As water-soluble and temperature-responsive polymers, PNIPAMand its copolymers have been extensively studied.As a sensitive and convenient analytic technique, fluorescence detection hasbeen widely used in molecular recognition, bio-labeling, cell imaging and otherfields, and becomes an essential detection mean in chemical and biological fields. Byintroducing fluorescent molecules with aggregation-induced emission (AIE) propertyand fluorescent carbon quantum dots into responsive polymers, we can construct aresponsive polymer micro-system and try to exhibit their potential application indetections for ions, pH, explosive and so on.In Chapter2, we design a dual emission polymer nanoparticles responsing topH and temperature. The core-shell polymer nanoparticles (PS/PNIPAM-co-PAA)are synthesized. Two kinds of photoluminescent molecules with similar excitationwavelengths, a rare earth complex with red emission and a quaternary ammoniumtetraphenylethylene derivative (d-TPE) with blue emission, are inserted intopolymeric core and shell, respectively. The PL intensities of the nanoparticles exhibita linear temperature response in the range of10and80oC with a change by a step ofa factor of5. Furthermore, blue emission from the shell exhibits a linear pH response between pH6.5and7.6with a resolution of0.1unit, as well as the red emission fromthe core is constant from pH-independance. Accordingly, the hydrogel nanoparticlesshow different purple and red coloration in neutral and acidic environments,enabling the discrimination of healthy (pH7.4) and cancer cells (pH6.5),respectively. These stimuli-responsive PL nanoparticles have potential application inbiology and chemistry, including bio-and chemo-sensors, biological imaging, cancerdiagnosis, and externally activated release of anticancer drugs.In Chapter3, in order to extend the study on responsive polymer micro-system,we improve a kind of nanoparticles with biocompatibility and cell targeting. Folicacid (FA) is brought to synthesize fluorescent carbon quantum dots for selectiveimaging of specific cancer cells. A simple, low-cost and one-step microwaveapproach has been demonstrated for the synthesis of water-soluble carbon dots(C-dots). The average size of the resulting C-dots is about4nm. From thephotoluminescence (PL) measurements, the C-dots exhibit good stability and intensePL with the high quantum yield (QY) at Ca.25%. Significantly, the C-dots haveexcellent biocompatibility and selective imaging for folate receptor (FR)-positivecancerous cells from normal cells. These exciting results indicate the as-preparedC-dots are promising biocompatible probe for cancer diagnosis and treatment.Further, gadolinium ions [Gd (III)] are interacted with the carboxyl of carbon dots toprepare a modified nanodot (Gd/C dot). Due to the magnetic properties from Gd (III)and fluorescent properties from carbon dots, the modified carbon dots withdual-function are obtained, which can be applied on dual-channel of fluorescenceand magnetic imaging.In Chapter4, we design to transfer our responsive polymer system into films tofabricate multi-functional sensitive devices. First, we prepared thethermo-responsive photoluminescent (PL) polymer brushes device as a platform forselective and sensitive detection of Cr (VI). As positive charged fluorescentmolecules of quaternary ammonium, tetraphenylethylene derivatives (d-TPE)molecules are immobilized in the thermo-responsive polymer brushes of PNIPAM-co-PAA by coloumb force, which leads to the observation of immobilizedinduced emission (IIE) phenomenon. The emission intensity is improved hundreds oftimes comparing with d-TPE aqueous solution. As a result, we obtain a novelthermo-responsive PL polymer brushes film device. The PL intensity of the deviceexhibits linear and reversible response in a large temperature range (4-60°C) andshows a highly PL quenching for sensitive and selective detection of Cr (VI) ratherthan Cr (III), the limit of detection can reach as low as0.05ppm, which indicates apromising sensor device of thermometer for environmental monitoring, laboratoryanalysis and other various applications.Moreover, we prepared the fluorescent polymer brushes film as a device forultrasensitive and selective detection of TNT. As positive charged fluorescentmolecules of quaternary ammonium tetraphenylethylene derivatives (d-TPE) wereself-assembled on the brushes of poly(acrylic acid)(PAAc) by coulomb force, weobtained a novel fluorescent polymer brushes film with excellent photoluminescenceproperties, and the emission intensity could be quantitatively and sensitivelyresponsive to2,4,6-trinitrotoluene (TNT) due to the electron transfer between d-TPEand TNT. The limit of detection of TNT was established to be0.1ppb in water. Thefluorescent device could also be used repeatedly for TNT detection, which indicateda promising application in trace explosive detection, environmental monitoring, andlaboratory analysis, etc.更多还原