Mochizuki Taketo, Sampei Shota, Suga Keishi, Watanabe Kanako, Welling Tom A J, Nagao Daisuke
Department of Chemical Engineering, Tohoku University, Sendai, Miyagi 9808579, Japan.
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Miyagi 9808578, Japan.
Anal Chem. 2024 Feb 27;96(8):3284-3290. doi: 10.1021/acs.analchem.3c03593. Epub 2024 Feb 14.
Nanoparticles (NPs) are utilized for the functionalization of composite materials and nanofluids. Although oxide NPs (e.g., silica (SiO)) exhibit less dispersibility in organic solvents or polymers due to their hydrophilic surface, the surface modification using silane coupling agents can improve their dispersibility in media with low dielectric constants. Herein, SiO NPs were functionalized using octyltriethoxysilane (OTES, C8) and dodecyltriethoxysilane (DTES, C12), wherein the degrees of surface modification of SiO@C8 and SiO@C12 were quantitatively evaluated based on the ratio of modifier to surface silanol group (θ) and the volume fraction of organic modifier to total particle volume (ϕ). The variations of surface properties were revealed by analyzing the Hansen solubility parameters (HSP). Particularly, the surface modification using OTES or DTES significantly affected the polarity (δ) of NPs. The local dielectric environments of surface-modified SiO NPs were characterized using a solvatochromic dye, Laurdan. By analyzing the peak position of the steady-state emission spectrum of Laurdan in a NP suspension, the apparent dielectric environments surrounding NPs (ε) were obtained. A good correlation between ϕ and ε was observed, indicating that ϕ is a reliable quantity for understanding the properties of surface-modified NPs. Furthermore, the generalized polarization () of NPs was investigated. The surface-modified SiO NPs with higher ϕ (≥0.15) exhibited > 0, suggesting that the modifiers are well-organized on the surface of NPs. The localized dielectric environment surrounding NPs could be predicted by analyzing the volume fraction of nonpolar moieties derived from modifiers. Alternatively, ε and can be utilized for understanding the properties of inorganic-organic hybrid NPs.
纳米颗粒（NPs）被用于复合材料和纳米流体的功能化。尽管氧化物纳米颗粒（如二氧化硅（SiO））由于其亲水性表面在有机溶剂或聚合物中表现出较低的分散性，但使用硅烷偶联剂进行表面改性可以提高它们在低介电常数介质中的分散性。在此，二氧化硅纳米颗粒使用辛基三乙氧基硅烷（OTES，C8）和十二烷基三乙氧基硅烷（DTES，C12）进行功能化，其中基于改性剂与表面硅醇基团的比例（θ）以及有机改性剂与总颗粒体积的体积分数（ϕ）对SiO@C8和SiO@C12的表面改性程度进行了定量评估。通过分析汉森溶解度参数（HSP）揭示了表面性质的变化。特别地，使用OTES或DTES进行表面改性显著影响了纳米颗粒的极性（δ）。使用溶剂化显色染料劳丹对表面改性的SiO纳米颗粒的局部介电环境进行了表征。通过分析劳丹在纳米颗粒悬浮液中的稳态发射光谱的峰值位置，获得了纳米颗粒周围的表观介电环境（ε）。观察到ϕ与ε之间有良好的相关性，表明ϕ是理解表面改性纳米颗粒性质的可靠量度。此外，还研究了纳米颗粒的广义极化（）。具有较高ϕ（≥0.15）的表面改性SiO纳米颗粒表现出>0，这表明改性剂在纳米颗粒表面排列良好。通过分析源自改性剂的非极性部分的体积分数可以预测纳米颗粒周围的局部介电环境。或者，ε和可用于理解无机-有机杂化纳米颗粒的性质。
