摘要荧光聚合物纳米粒子在疾病检测、生物成像、光电材料和化学传感等领域都有着重要的应用价值。但以传统聚集诱导淬灭型荧光分子为功能组分的纳米粒子,往往存在荧光量子产率(ФF)低、荧光强度调控区间窄等缺陷。而将新型的聚集诱导发光( AIE)型荧光分子引入纳米粒子后,由于其分子内旋转受到严重限制,其会发射强荧光。而且,AIE 分子浓度越高,分子聚集程度越大,荧光越亮。因此AIE 分子非常适合于制备高荧光强度和高荧光量子产率的纳米粒子。虽然 AIE型纳米粒子有优异的发光性能,但现行的制备方法存在 AIE 分子装载量不高、使用有机溶剂、过程繁琐等缺陷。为此,开发一种简便、可靠、易工业放大且绿色的AIE 纳米粒子的制备方法,对于推动 AIE 纳米材料制备技术的发展及其在各领域的广泛应用有非常重要意义。72394
本论文提出在绿色的水基细乳液体系中,通过St与AMTPS共聚合反应,制得了不同 AMTPS含量的St-AMTPS共聚物纳米粒子(简称SNP)。系统研究了AMTPS用量对粒子形态和尺寸、聚合反应动力学、纳米粒子和共聚物的发光性能的影响。透射电镜结果显示SNP系列纳米粒子呈现规整的球形,且尺寸分布较窄。由聚合反应动力学可知,该反应有较快的反应速率,不同AMTPS用量的体系,在反应60min时,St转化率均可达到80%以上。增长自由基易向AMTPS转移,因此随AMTPS用量增加,共聚物的分子量下降。在紫外光激发下,SNP系列纳米粒子发蓝绿色荧光,而且纳米粒子的荧光强度可以用AMTPS用量精确调控。但须指出的是,SNP系列纳米粒子的ФF相对较低,其中最高的SNP(AMTPS含量为20wt%)的ФF也仅为22。6%。随四氢呋喃/水混合溶剂中水的体积分率的增加,St-AMTPS 共聚物的荧光强度先缓慢增加,当水的体积分率超过70%后,共聚物荧光显著增加,当水的体积分率超过70%后,共聚物荧光显著增强,体现出典型的AIE特征。随聚合反应进行,分散相内聚合物分率增加,黏度也随之增加,而且分散相也逐渐由液态向固态转变,相应地乳液从最初的发弱荧光向发强荧光转变。
本论文的研究表明,在绿色水基细乳液体系中,以通用单体为主单体,与AIE功能单体共聚,能简便地制备AIE型聚合物纳米粒子。本论文所提出的方法有很好的灵活性和通用性,有望成为制备高荧光强度、高荧光量子产率和高生物相容性的AIE聚合物纳米粒子的通用技术。
Abstract: Fluorescent polymer nanoparticles (NPs) have been widely used in the fields of cell imaging, disease diagnosis, chemical sensing, and optoelectronic materials。 Fluorescent NPs using conventional aggregation-induced quenching (ACQ) fluorescent molecules as functional components often suffer from a low fluorescence quantum yield (ФF) and narrow regulation range of photoluminescence (PL) intensity。 However, when fluorescent molecules with an aggregation-induced emission (AIE) property were introduced into the fluorescent NPs, they can emit strong fluorescence because of the serious restriction of the intramolecular rotation。 Moreover, the PL intensity of AIE NPs can be significantly enhanced through the increase of the loading of AIE molecules, because the aggregation degree of AIE molecules is expected to be higher at an increased concentration。 Therefore, in compared with ACQ molecules, AIE ones are more promising to be used as fluorescent moiety to prepare fluorescent NPs with a high PL intensity and high ФF。 Although several innovative techniques have been designed to prepare AIE NPs, they more or less had some drawbacks, such as the low loading of AIE molecules, use of organic solvent, and complex and tedious preparation process。 Therefore, it is highly desired to invent a novel, efficient, scalable, green, and reproducible technique to synthesize AIE NPs。 The convenient preparation of AIE NPs may highly promote the development of various AIE NPs and broaden their applications。