Roka Nikoletta, Pitsikalis Marinos
Industrial Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece.
Polymers (Basel). 2025 Apr 21;17(8):1122. doi: 10.3390/polym17081122.
Novel amphiphilic block copolymers of N-vinyl pyrrolidone (NVP) and either n-hexyl methacrylate (HMA, PNVP--PHMA) or stearyl methacrylate (SMA, PNVP--PSMA) were prepared by RAFT polymerization techniques and the sequential addition of monomers starting from the polymerization of NVP and using two different Chain Transfer Agents, CTAs. PNVP--PHMA are amorphous block copolymers containing constituent blocks with both high and low Tg values, whereas PNVP--PSMA are amorphous-semi-crystalline copolymers. Samples with different molecular weights and compositions were obtained. The copolymers were microphase-separated, but partial mixing was also observed. The presence of the amorphous PNVP block reduced the crystallinity of the PSMA blocks in the PNVP--PSMA copolymers. The thermal stability of the blocks was influenced by both constituents. The self-assembly behavior in THF, which is a selective solvent for polymethacrylate blocks, and in aqueous solutions, where PNVP was soluble, was examined. Unimolecular or low-aggregation-number micelles were obtained in THF for both types of samples. On the contrary, high-aggregation-number, spherical, and compact micelles were revealed in aqueous solutions. The increase in the steric hindrance of the side ester group of the polymethacrylate chain led to slightly lower degrees of association. The hydrophobic compound curcumin was efficiently encapsulated within the micellar core of the supramolecular structures in aqueous solutions. Micelles with higher aggregation numbers were more efficient in the encapsulation of curcumin. The results of this study were compared with those obtained from other block copolymers based on PNVP.
通过可逆加成-断裂链转移（RAFT）聚合技术，以N-乙烯基吡咯烷酮（NVP）为起始单体，并使用两种不同的链转移剂（CTA），依次添加甲基丙烯酸正己酯（HMA，PNVP-PHMA）或甲基丙烯酸硬脂酯（SMA，PNVP-PSMA），制备了新型两亲性嵌段共聚物。PNVP-PHMA是无定形嵌段共聚物，其组成嵌段具有高Tg值和低Tg值，而PNVP-PSMA是无定形-半结晶共聚物。获得了具有不同分子量和组成的样品。共聚物发生了微相分离，但也观察到了部分混合现象。无定形PNVP嵌段的存在降低了PNVP-PSMA共聚物中PSMA嵌段的结晶度。各嵌段的热稳定性受两种组分的影响。研究了在聚甲基丙烯酸酯嵌段的选择性溶剂四氢呋喃（THF）中以及在PNVP可溶的水溶液中的自组装行为。两种类型的样品在THF中均形成了单分子或低聚集数的胶束。相反，在水溶液中则形成了高聚集数的球形紧密胶束。聚甲基丙烯酸酯链侧酯基空间位阻的增加导致缔合度略有降低。疏水性化合物姜黄素被有效地包裹在水溶液中超分子结构的胶束核内。聚集数较高的胶束对姜黄素的包裹效率更高。本研究结果与基于PNVP的其他嵌段共聚物的研究结果进行了比较。
