van Ravensteijn Bas G P, Vilanova Neus, de Feijter Isja, Kegel Willem K, Voets Ilja K
Van 't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for NanoMaterials Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Institute for Complex Molecular Systems, Laboratory of Macromolecular Organic Chemistry, and Laboratory of Physical Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
ACS Omega. 2017 Apr 28;2(4):1720-1730. doi: 10.1021/acsomega.7b00111. eCollection 2017 Apr 30.
In this article, we report the synthesis and physical characterization of colloidal polystyrene particles that carry water-soluble supramolecular ,',″,-trialkyl-benzene-1,3,5-tricarboxamides (BTAs) on their surface. These molecules are known to assemble into one-dimensional supramolecular polymers via noncovalent interactions. By tethering the BTAs to charge-stabilized particles, the clustering behavior of the resulting colloids was dictated by a balance between interparticle electrostatic repulsion and the BTA-mediated attractions. Through careful tuning of the dispersing medium's ionic strength, a regime was found in which particle aggregation could be reversibly induced upon heating the dispersion. These findings clearly indicate that hydrophobic interactions, which become stronger upon heating, play an important role during the clustering process. Besides the thermoreversible nature of the generated hydrophobic interparticle attractions, we found the clustering to be selective, that is, the BTA-functionalized colloids do not interact with nonfunctionalized hydrophobic polystyrene particles. This selectivity in the association process can be rationalized by the preferred stacking of the surface-tethered BTAs. These selective intermolecular/particle bonds are likely stabilized by the formation of hydrogen bonds, as previously observed for analogous molecular BTA assemblies. The resulting driving force responsible for particle clustering is therefore dual in nature and depends on both hydrophobic attractions and hydrogen bonding.
在本文中，我们报道了表面带有水溶性超分子','″,-三烷基苯-1,3,5-三甲酰胺（BTAs）的胶体聚苯乙烯颗粒的合成及物理表征。已知这些分子通过非共价相互作用组装成一维超分子聚合物。通过将BTAs连接到电荷稳定的颗粒上，所得胶体的聚集行为由颗粒间静电排斥和BTA介导的吸引力之间的平衡决定。通过仔细调节分散介质的离子强度，发现了一种在加热分散体时可可逆诱导颗粒聚集的状态。这些发现清楚地表明，加热时变强的疏水相互作用在聚集过程中起重要作用。除了所产生的疏水颗粒间吸引力的热可逆性质外，我们发现聚集具有选择性，即BTA功能化的胶体不与非功能化的疏水聚苯乙烯颗粒相互作用。结合过程中的这种选择性可以通过表面连接的BTAs的优先堆积来解释。这些选择性分子间/颗粒键可能通过氢键的形成而稳定，正如之前在类似的分子BTA组装体中所观察到的那样。因此，导致颗粒聚集的驱动力本质上是双重的，并且取决于疏水吸引力和氢键两者。
