State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, PR China.
State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, PR China.
J Colloid Interface Sci. 2021 Mar;585:237-249. doi: 10.1016/j.jcis.2020.11.042. Epub 2020 Nov 19.
Organic radical polymers with tailored pendant functionalities have emerged as exciting and promising materials for their application versatility. Moreover, eco-friendly polymer-based organic nanomaterials with redox-active pendant side groups can replace the harmful heavy metal-based inorganic materials. On the other hand, self-assembled nanomaterials are of great interest and attracted more attention recently for their promising application in different advanced fields, but it is yet challenging to predict suitable hydrophilic-lipophilic balance (HLB) for stimuli-responsive random copolymers assembly due to structural irregularity. Among several experimental techniques, electron paramagnetic resonance (EPR) spectroscopy plays a unique and promising role in revealing structural and dynamic information of nanostructured radical containing materials.
In this study, a series of spin labeled amphiphilic random copolymers poly(methyl methacrylate-co-acrylic acid) have been synthesized and characterized by FT-IR, UV-Vis spectroscopies, TGA, DSC and water contact angle (CA) techniques. Their electrochemical properties have been determined by cyclic voltammetry (CV) in different organic solvents. EPR spectroscopy has been applied with other analytical techniques to elucidate the smart supramolecular nanoparticles (SNPs) formation, stimuli-responsiveness and structural changes through the dynamics of different molecular interactions.
The structural and dynamic information of self-assembled nanoparticles have been observed to be dependent on multiple-stimuli-responsiveness in different microenvironments by applying physiological and chemical parameters such as the different concentration of radicals, pH, temperature, nature of the solvent and reducing agent. The obtained results reveal the knowledge to understand insight into the mechanism for the formation of stimuli-responsive colloidal nanoparticles assembled from amphiphilic random copolymers with apt HLB value. The CV results reveal that the charge transfer process of the nanoparticles in solution was diffusion regulated and depended on the accessibility of radicals. The radical (spin labeled) polymers offer a broad way to develop stimuli-responsive materials in various colloidal nanostructures by changing the microenvironment, appreciating their potential advanced applications in electronic devices, catalysis, stimuli-triggered drug/gene delivery and reactive oxygen species (ROS) scavenger.
具有定制侧基功能的有机自由基聚合物因其应用的多功能性而成为令人兴奋且有前途的材料。此外，具有氧化还原活性侧基的环保型聚合物基有机纳米材料可以替代有害的重金属基无机材料。另一方面，自组装纳米材料因其在不同先进领域的有前途的应用而引起了极大的兴趣和关注，但由于结构不规则，预测刺激响应型无规共聚物组装的合适亲水-亲脂平衡（HLB）仍然具有挑战性。在几种实验技术中，电子顺磁共振（EPR）光谱在揭示含有纳米结构自由基的材料的结构和动态信息方面发挥着独特而有前途的作用。
在这项研究中，通过傅里叶变换红外光谱（FT-IR）、紫外-可见光谱、热重分析（TGA）、差示扫描量热法（DSC）和水接触角（CA）技术合成并表征了一系列带有自旋标记的两亲性无规共聚物聚（甲基丙烯酸甲酯-共-丙烯酸）。通过在不同有机溶剂中的循环伏安法（CV）确定了它们的电化学性质。EPR 光谱已与其他分析技术一起应用，通过不同分子相互作用的动力学来阐明智能超分子纳米粒子（SNP）的形成、刺激响应性和结构变化。
通过应用生理和化学参数（例如自由基的不同浓度、pH 值、温度、溶剂和还原剂的性质），观察到自组装纳米粒子的结构和动态信息取决于不同微环境中的多刺激响应性。所得结果揭示了了解由具有适当 HLB 值的两亲性无规共聚物组装形成的刺激响应胶体纳米粒子的形成机制的知识。CV 结果表明，纳米粒子在溶液中的电荷转移过程是扩散调节的，并且取决于自由基的可及性。自由基（自旋标记）聚合物为通过改变微环境在各种胶体纳米结构中开发刺激响应材料提供了广泛的途径，这对其在电子设备、催化、刺激触发药物/基因传递和活性氧（ROS）清除剂等方面的潜在先进应用具有重要意义。
