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Interactions between brush-grafted nanoparticles within chemically identical homopolymers: the effect of brush polydispersity†
Soft Matter ( IF 2.9 ) Pub Date : 2018-01-03 00:00:00 , DOI: 10.1039/c7sm02483e So Jung Park 1, 2, 3, 4, 5 , Seyong Kim 5, 6, 7, 8 , Daeseong Yong 1, 2, 3, 4, 5 , Youngson Choe 5, 9, 10, 11 , Joona Bang 5, 6, 7, 8 , Jaeup U. Kim 1, 2, 3, 4, 5
Soft Matter ( IF 2.9 ) Pub Date : 2018-01-03 00:00:00 , DOI: 10.1039/c7sm02483e So Jung Park 1, 2, 3, 4, 5 , Seyong Kim 5, 6, 7, 8 , Daeseong Yong 1, 2, 3, 4, 5 , Youngson Choe 5, 9, 10, 11 , Joona Bang 5, 6, 7, 8 , Jaeup U. Kim 1, 2, 3, 4, 5
Affiliation
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We systematically examined the polymer-mediated interparticle interactions between polymer-grafted nanoparticles (NPs) within chemically identical homopolymer matrices through experimental and computational efforts. In experiments, we prepared thermally stable gold NPs grafted with polystyrene (PS) or poly(methyl methacrylate) (PMMA), and they were mixed with corresponding homopolymers. The nanocomposites are well dispersed when the molecular weight ratio of free to grafted polymers, α, is small. For α above 10, NPs are partially aggregated or clumped within the polymer matrix. Such aggregation of NPs at large α has been understood as an autophobic dewetting behavior of free homopolymers on brushes. In order to theoretically investigate this phenomenon, we calculated two particle interaction using self-consistent field theory (SCFT) with our newly developed numerical scheme, adopting two-dimensional finite volume method (FVM) and multi-coordinate-system (MCS) scheme which makes use of the reflection symmetry between the two NPs. By calculating the polymer density profile and interparticle potential, we identified the effects of several parameters such as brush thickness, particle radius, α, brush chain polydispersity, and chain end mobility. It was found that increasing α is the most efficient method for promoting autophobic dewetting phenomenon, and the attraction keeps increasing up to α = 20. At small α values, high polydispersity in brush may completely nullify the autophobic dewetting, while at intermediate α values, its effect is still significant in that the interparticle attractions are heavily reduced. Our calculation also revealed that the grafting type is not a significant factor affecting the NP aggregation behavior. The simulation result qualitatively agrees with the dispersion/aggregation transition of NPs found in our experiments.
中文翻译：
化学相同的均聚物中刷接枝的纳米颗粒之间的相互作用：刷多分散性的影响†
我们通过实验和计算努力，系统地研究了化学相同的均聚物基质中聚合物接枝的纳米颗粒（NPs）之间的聚合物介导的颗粒间相互作用。在实验中，我们制备了接有聚苯乙烯（PS）或聚甲基丙烯酸甲酯（PMMA）的热稳定金纳米颗粒，并将它们与相应的均聚物混合。当游离聚合物与接枝聚合物的分子量比α小时，纳米复合材料会很好地分散。对于大于10的α，NP在聚合物基质中部分聚集或团聚。这样的NP在大α处聚集已被理解为游离均聚物在刷子上的憎水去湿行为。为了从理论上研究这种现象，我们使用自洽场理论（SCFT）和我们最新开发的数值方案，通过二维有限体积法（FVM）和多坐标系（MCS）方案，计算了两个粒子相互作用。利用了两个NP之间的反射对称性。通过计算聚合物的密度分布和颗粒间的电势，我们确定了几个参数的影响，例如刷子厚度，颗粒半径，α，刷子链多分散性和链端迁移率。发现增加α是促进自疏水性脱湿现象的最有效方法，并且吸引力持续增加到α =20。在较小的α值下，刷子中的高多分散性可能会完全消除疏水性反润湿作用，而在中等的α值下，其效果仍然很明显，因为粒子间的吸引力会大大降低。我们的计算还表明，嫁接类型不是影响NP聚集行为的重要因素。模拟结果在质量上与我们实验中发现的NPs的分散/聚集过渡相吻合。
更新日期：2018-01-03
中文翻译：
化学相同的均聚物中刷接枝的纳米颗粒之间的相互作用：刷多分散性的影响†
我们通过实验和计算努力，系统地研究了化学相同的均聚物基质中聚合物接枝的纳米颗粒（NPs）之间的聚合物介导的颗粒间相互作用。在实验中，我们制备了接有聚苯乙烯（PS）或聚甲基丙烯酸甲酯（PMMA）的热稳定金纳米颗粒，并将它们与相应的均聚物混合。当游离聚合物与接枝聚合物的分子量比α小时，纳米复合材料会很好地分散。对于大于10的α，NP在聚合物基质中部分聚集或团聚。这样的NP在大α处聚集已被理解为游离均聚物在刷子上的憎水去湿行为。为了从理论上研究这种现象，我们使用自洽场理论（SCFT）和我们最新开发的数值方案，通过二维有限体积法（FVM）和多坐标系（MCS）方案，计算了两个粒子相互作用。利用了两个NP之间的反射对称性。通过计算聚合物的密度分布和颗粒间的电势，我们确定了几个参数的影响，例如刷子厚度，颗粒半径，α，刷子链多分散性和链端迁移率。发现增加α是促进自疏水性脱湿现象的最有效方法，并且吸引力持续增加到α =20。在较小的α值下，刷子中的高多分散性可能会完全消除疏水性反润湿作用，而在中等的α值下，其效果仍然很明显，因为粒子间的吸引力会大大降低。我们的计算还表明，嫁接类型不是影响NP聚集行为的重要因素。模拟结果在质量上与我们实验中发现的NPs的分散/聚集过渡相吻合。
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