Department of Chemistry, CICECO-Aveiro Institute of Materials, Campus de Santiago, University of Aveiro, 3810-193 Aveiro, Portugal.
J Colloid Interface Sci. 2019 Jun 1;545:251-258. doi: 10.1016/j.jcis.2019.03.034. Epub 2019 Mar 12.
Reversible addition fragmentation chain transfer (RAFT) - assisted encapsulating emulsion polymerization (REEP) has received considerable attention as an efficient strategy to prepare colloidal stable shell@core nanoparticles. Generally, amphipathic macroRAFT agents are used but the effect of working above or below the critical micelle concentration (CMC) of macroRAFT agents needs to be addressed. Hence, it is necessary to understand if this parameter has an impact not only on the stability of the colloids but also on the molecular mass of the polymer shell.
Here, the CMC of three different macroRAFT agent was determined and the effect of macroRAFT agents concentration on the colloidal stability of gold nanoparticles coated with macroRAFT agents (macroRAFT@Au) assessed. The subsequent chain extension from macroRAFT@Au NPs, resulting in encapsulated Au nanoparticles (copolymer@Au), has also been systematically studied.
Using the REEP approach it was possible to obtain stable encapsulated Au NPs. Moreover, this strategy opens the possibility of adjusting the macroRAFT agents concentration to tune the length of the polymer chains grown around Au cores which is of major interest for the design of biosensors based on responsive polymer shells, such as pH, temperature and photoluminescence quenching.
可逆加成-断裂链转移（RAFT）辅助包埋乳液聚合（REEP）作为一种有效的策略，已经受到了相当多的关注，用于制备胶体稳定的核壳纳米粒子。通常，使用两亲性大分子 RAFT 试剂，但需要解决大分子 RAFT 试剂工作在临界胶束浓度（CMC）以上或以下的效果。因此，有必要了解这一参数不仅对胶体稳定性有影响，而且对聚合物壳的分子量也有影响。
本研究确定了三种不同大分子 RAFT 试剂的 CMC，并评估了大分子 RAFT 试剂浓度对金纳米粒子表面涂覆大分子 RAFT 试剂（macroRAFT@Au）的胶体稳定性的影响。随后，从 macroRAFT@Au NPs 进行的链延伸，导致包裹金纳米粒子（copolymer@Au），也得到了系统的研究。
采用 REEP 方法可以得到稳定的包裹 Au NPs。此外，这种策略为调整大分子 RAFT 试剂浓度以调节围绕 Au 核生长的聚合物链长度提供了可能性，这对于设计基于响应性聚合物壳的生物传感器非常重要，例如 pH 值、温度和光致荧光猝灭。
