Chremos Alexandros, Douglas Jack F, Basser Peter J, Horkay Ferenc
Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Soft Matter. 2022 Aug 24;18(33):6278-6290. doi: 10.1039/d2sm00681b.
Owing to their great importance in materials science and other fields, we investigate the solution and osmotic properties of uncharged compact nanogel particles over a wide range of solvent quality and particle concentration by molecular dynamics (MD) simulations. We characterize the osmotic pressure by estimating the second and third virial coefficients, and by extension, we identify the -point where the second virial coefficient vanishes. Calculations of the structure factor indicate that these particles are similar to macrogels in that the particle-like scattering profile disappears at moderate concentrations. We also find that improving the solvent quality enhances the spatial segmental uniformity, while significant heterogeneous structure arises near the -point. Well below the -point where the second osmotic virial coefficient vanishes, these heterogeneous structures become less prevalent as the particles tend to collapse. We also investigate the degree of swelling and structure of compact nanogel particles with a variable excluded volume interaction and gel particle concentration. The osmotic modulus and the scaling exponents in good and -point conditions of these gels are characteristic of interacting randomly branched polymers, , "lattice animals".
由于它们在材料科学和其他领域的重要性，我们通过分子动力学（MD）模拟研究了在广泛的溶剂质量和颗粒浓度范围内不带电致密纳米凝胶颗粒的溶液和渗透性质。我们通过估计第二和第三维里系数来表征渗透压，进而确定第二维里系数消失的θ点。结构因子的计算表明，这些颗粒与大凝胶相似，因为在中等浓度下颗粒状散射轮廓消失。我们还发现，改善溶剂质量会增强空间链段均匀性，而在θ点附近会出现明显的异质结构。在第二渗透维里系数消失的θ点以下，随着颗粒趋于塌陷，这些异质结构变得不那么普遍。我们还研究了具有可变排除体积相互作用和凝胶颗粒浓度的致密纳米凝胶颗粒的溶胀程度和结构。这些凝胶在良好和θ点条件下的渗透模量和标度指数是相互作用的无规支化聚合物，即“晶格动物”的特征。
