A poly(N,N′-dimethylacrylamide) (PDMAC) precursor is chain-extended via reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization of diacetone acrylamide (PDAAM) to produce PDMAC₇₇-PDAAM₄₀ spherical nanoparticles. Post-polymerization core-crosslinking of such nanoparticles was performed at 20 °C, and the resulting covalently stabilized nanoparticles survive exposure to methanol. The linear and core-crosslinked nanoparticles were subjected to high-shear homogenization in turn in the presence of n-dodecane to form macroemulsions. Subsequent processing of these macroemulsions via high-pressure microfluidization produced nanoemulsions. When using the core crosslinked nanoparticles, the droplet diameter was strongly dependent on the copolymer concentration. This indicates that such nanoparticles remain intact under the processing conditions, leading to formation of genuine Pickering nanoemulsions with a z-average diameter of 244 ± 60 nm. In contrast, the linear nanoparticles undergo disassembly to afford molecularly dissolved diblock copolymer chains, which stabilize oil droplets of 170 ± 59 nm diameter. The long-term stability of these two types of n-dodecane-in-water nanoemulsions with respect to Ostwald ripening was examined using analytical centrifugation. When prepared at the same copolymer concentration, Pickering nanoemulsions stabilized by core-crosslinked nanoparticles proved to be significantly more stable than the nanoemulsion stabilized by the amphiphilic PDMAC₇₇-PDAAM₄₀ chains. Moreover, higher copolymer concentrations led to a significantly faster rate of droplet growth. This is attributed to excess copolymer facilitating the diffusion of n-dodecane through the aqueous phase. Finally, analytical centrifugation is used to assess the long-term stability of the analogous squalane-in-water nanoemulsions. These systems are much more stable than the corresponding n-dodecane-in-water nanoemulsions, regardless of whether the copolymer is adsorbed as sterically stabilized nanoparticles or surface-active chains.

中文翻译：

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使用二嵌段共聚物纳米颗粒制备的 Pickering 纳米乳液的长期稳定性：纳米颗粒核交联的影响、油类型以及过量共聚物所起的作用


聚( N , N'-二甲基丙烯酰胺)(PDMAC)前体通过双丙酮丙烯酰胺(PDAAM)的可逆加成-断裂链转移(RAFT)水分散聚合进行扩链，产生PDMAC ₇₇ -PDAAM ₄₀球形纳米颗粒。这种纳米颗粒的聚合后核交联在 20°C 下进行，所得共价稳定的纳米颗粒在暴露于甲醇后仍能幸存。线性和核交联的纳米粒子在正十二烷存在下依次进行高剪切均化以形成粗乳液。随后通过高压微流化处理这些粗乳液产生纳米乳液。当使用核心交联纳米粒子时，液滴直径强烈依赖于共聚物浓度。这表明此类纳米粒子在加工条件下保持完整，从而形成z平均直径为 244 ± 60 nm 的真正皮克林纳米乳液。相比之下，线性纳米粒子经过分解，提供分子溶解的二嵌段共聚物链，从而稳定直径为 170 ± 59 nm 的油滴。使用分析离心法检查了这两种类型的水包正十二烷纳米乳液在奥斯特瓦尔德熟化方面的长期稳定性。当以相同的共聚物浓度制备时，由核交联纳米颗粒稳定的 Pickering 纳米乳液被证明比由两亲性 PDMAC ₇₇ -PDAAM ₄₀链稳定的纳米乳液明显更稳定。此外，较高的共聚物浓度导致液滴生长速度显着加快。 这是由于过量的共聚物促进了正十二烷通过水相的扩散。最后，使用分析离心来评估类似的角鲨烷水纳米乳液的长期稳定性。这些系统比相应的水包正十二烷纳米乳液稳定得多，无论共聚物是否作为空间稳定的纳米颗粒或表面活性链被吸附。