Sanna Angotzi Marco, Mameli Valentina, Khanal Shankar, Veverka Miroslav, Vejpravova Jana, Cannas Carla
Department of Chemical and Geological Sciences, University of Cagliari S.S. 554 Bivio per Sestu, Monserrato 09042 CA Italy
Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM) Via Giuseppe Giusti 9 50121 Firenze (FI) Italy.
Nanoscale Adv. 2021 Nov 8;4(2):408-420. doi: 10.1039/d1na00478f. eCollection 2022 Jan 18.
In this work, the effect of different molecular coatings on the alternating magnetic field-induced heating properties of 15 nm maghemite nanoparticles (NPs) in water dispersions was studied at different frequencies (159-782 kHz) and field amplitudes (100-400 G). The original hydrophobic oleate coating was replaced with dimercaptosuccinic acid (DMSA) or polyethylene glycol trimethoxysilane (PEGTMS), while cetrimonium bromide (CTAB) or stearic acid-poloxamer 188 (SA-P188) was intercalated or encapsulated, respectively, to transfer the dispersions into water. Surface modification, based on intercalation processes, induced clustering phenomena with the formation of spherical-like assemblies (CTAB and SA-P188), while ligand-exchange strategies kept the particles isolated. The clustering phenomenon has detrimental effects on the heating performances compared with isolated systems, in line with the reduction of Brown relaxation times. Furthermore, broader comprehension of the heating phenomenon in this dynamic system is obtained by following the evolution of SPA and ILP with time and temperature beyond the initial stage.
在本研究中，我们考察了不同分子涂层对15 nm磁赤铁矿纳米颗粒（NPs）水分散体在不同频率（159 - 782 kHz）和场强（100 - 400 G）下交变磁场诱导加热性能的影响。原始的疏水性油酸涂层被二巯基琥珀酸（DMSA）或聚乙二醇三甲氧基硅烷（PEGTMS）取代，同时分别插入十六烷基三甲基溴化铵（CTAB）或包裹硬脂酸 - 泊洛沙姆188（SA - P188），以使分散体能够分散于水中。基于插入过程的表面改性会引发团聚现象，形成球状聚集体（CTAB和SA - P188），而配体交换策略则能使颗粒保持分散状态。与孤立体系相比，团聚现象对加热性能有不利影响，这与布朗弛豫时间的缩短一致。此外，通过跟踪初始阶段之后SPA和ILP随时间和温度的变化，能够更深入地理解这个动态系统中的加热现象。
