Forg Sandra, Guo Xuhong, von Klitzing Regine
Soft Matter at Interfaces (SMI), Institute for Physics of Condensed Matter, Technical University of Darmstadt, 64289 Darmstadt, Germany.
School of Chemical Engineering, East China University of Science and Technology, 200231 Shanghai, China.
ACS Appl Mater Interfaces. 2024 Jan 10;16(1):1521-1534. doi: 10.1021/acsami.3c15134. Epub 2023 Dec 25.
The combination of the catechol-containing comonomer dopamine methacrylamide (DMA) with stimuli-responsive poly(-isopropylacrylamide) (PNIPAM) microgels bears a huge potential in research and for applications due to the versatile properties of catechols. This research gives the first detailed insights into the influence of DMA on the swelling of PNIPAM microgels and their nanomechanical properties. Dynamic light scattering measurements showed that DMA decreases the volume phase transition temperature and completion temperature due to its higher hydrophobicity when compared to NIPAM, while sharpening the transition. The cross-linking ability of DMA decreases the swelling ratios and mesh sizes of the microgels. Microgels adsorbed at the solid surface are characterized by atomic force microscopy─as the DMA content increases, microgels protrude more from the surface. Force spectroscopy measurements below and above the volume phase transition temperature display a stiffening of the microgels with the incorporation of DMA and upon heating across its entire cross section as evidenced by an increase in the modulus. This confirms the cross-linking ability of DMA. The affine network factor β, derived from the Flory-Rehner theory, is linearly correlated with the moduli of both pure PNIPAM and P(NIPAM--DMA) microgels. However, large DMA amounts hinder the microgel shrinking while maintaining mechanical stiffness, possibly due to catechol interactions within the microgel network.
含儿茶酚的共聚单体多巴胺甲基丙烯酰胺（DMA）与刺激响应性聚（N-异丙基丙烯酰胺）（PNIPAM）微凝胶相结合，由于儿茶酚具有多种特性，在研究和应用方面具有巨大潜力。本研究首次详细深入地探讨了DMA对PNIPAM微凝胶溶胀及其纳米力学性能的影响。动态光散射测量表明，与NIPAM相比，DMA因其更高的疏水性而降低了体积相变温度和完成温度，同时使转变更加尖锐。DMA的交联能力降低了微凝胶的溶胀率和网孔尺寸。通过原子力显微镜对吸附在固体表面的微凝胶进行表征——随着DMA含量的增加，微凝胶从表面突出得更多。在体积相变温度以下和以上进行的力谱测量表明，随着DMA的加入以及在整个横截面加热时，微凝胶会变硬，这通过模量的增加得到证明。这证实了DMA的交联能力。从弗洛里-雷纳理论推导得出的仿射网络因子β与纯PNIPAM和P（NIPAM-DMA）微凝胶的模量呈线性相关。然而，大量的DMA会阻碍微凝胶收缩，同时保持机械刚度，这可能是由于微凝胶网络内的儿茶酚相互作用所致。
