Insights into the internal structures of nanogels using a versatile asymmetric-flow field-flow fractionation method.
Insights into the internal structures of nanogels using a versatile asymmetric-flow field-flow fractionation method.
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使用多功能非对称流场流分级方法深入了解纳米凝胶的内部结构。
DOI：
10.1039/d0na00314j
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发表时间：
2020-10-13
影响因子：
4.7
通讯作者：
McDonald, Tom O.
中科院分区：
文献类型：
--
作者：
Niezabitowska, Edyta;Town, Adam R.;Sabagh, Bassem;Moctezuma, Marissa D. Morales;Kearns, Victoria R.;Spain, Sebastian G.;Rannard, Steve P.;McDonald, Tom O.
聚(N-异丙基丙烯酰胺)(PNIPAM)纳米凝胶是一种备受关注的胶体材料。在这项工作中，我们建立了一种通用的非对称流场-流动分馏(AF4)方法，该方法可以提供高分辨率的颗粒尺寸和流体力学直径为65-310 nm的纳米凝胶样品的结构信息，因此不同的化学成分。为了实现这一在线，分别使用多角度光散射和动态光散射探测器来测量旋转半径(Rg)和流体动力半径(Rh)。评估了两种不同的洗脱剂和一系列的交叉流动，以便为不同的纳米凝胶样品提供有效的分级和高回收率。我们发现，使用0.1M NaNO3作为洗脱剂，初始错流1mLmin−1为所有被测样品提供了最佳的分离条件。利用这种方法，我们分析了两种类型的样品，即自由基分散聚合制备的PNIPAM纳米凝胶和可逆加成-断裂链转移分散聚合制备的聚(丙烯酸)-b-PNIPAM交联纳米凝胶。我们可以确定不同尺寸的自由基纳米凝胶具有不同的内部结构；形状因子(Rg/Rh)在0.58-0.73之间，表明最小的纳米凝胶具有均匀的内部交联密度，而较大的纳米凝胶与壳层相比具有更密集的交联核。聚丙烯酸-b-PNIPAM交联型纳米凝胶具有清晰的核壳结构，因为所有的交联剂都包含在纳米凝胶的核心中。这项工作展示了一种通用的不对称流场-流动分馏方法来表征聚(N-异丙基丙烯酰胺)纳米凝胶的尺寸和内部结构。
Poly(N-isopropylacrylamide) (pNIPAM) nanogels are a highly researched type of colloidal material. In this work, we establish a versatile asymmetric-flow field-flow fractionation (AF4) method that can provide high resolution particle sizing and also structural information on nanogel samples from 65–310 nm in hydrodynamic diameter and so different chemical compositions. To achieve this online multi-angle light scattering and dynamic light scattering detectors were used to provide measurement of the radius of gyration (Rg) and hydrodynamic radius (Rh) respectively. Two different eluents and a range of cross-flows were evaluated in order to provide effective fractionation and high recovery for the different nanogel samples. We found that using 0.1 M NaNO3 as the eluent and an initial cross-flow of 1 mL min−1 provided optimal separation conditions for all samples tested. Using this method, we analysed two types of samples, pNIPAM nanogels prepared by free radical dispersion polymerisation with increasing diameters and analysed poly(acrylic acid)-b-pNIPAM crosslinked nanogels prepared by reversible addition–fragmentation chain transfer dispersion polymerisation. We could determine that the differently sized free radical nanogels possessed differing internal structures; shape factors (Rg/Rh) ranged from 0.58–0.73 and revealed that the smallest nanogel had a homogeneous internal crosslinking density, while the larger nanogels had a more densely crosslinked core compared to the shell. The poly(acrylic acid)-b-pNIPAM crosslinked nanogels displayed clear core–shell structures due to all the crosslinking being contained in the core of the nanogel. This work demonstrates a versatile asymmetric-flow field-flow fractionation method for characterising the sizes and internal structures of poly(N-isopropylacrylamide) nanogels.
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影响因子：
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作者：
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通讯作者：
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