Chen Cangyi, Tang Ping, Qiu Feng, Shi An-Chang
The State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University , Shanghai 200433, China.
Department of Physics and Astronomy, McMaster University , Hamilton, Ontario, Canada L8S 4M1.
J Phys Chem B. 2016 Jun 23;120(24):5553-63. doi: 10.1021/acs.jpcb.6b03005. Epub 2016 Jun 14.
The conformation of homodendrimers and amphiphilic dendrimers in various solvents is studied using classical density functional theory (DFT), in which the excluded-volume effects are treated explicitly. For homodendrimers in an athermal solvent, DFT results predict a remarkable fold-back behavior for the outer generation of segments, supporting the dense-core model. A coil-to-globule transition is observed for homodendrimers in a poor solvent. The size of the dendrimers, characterized by the radius of gyration, ⟨Rg⟩, is found to follow the scaling relationship, ⟨Rg⟩ ∼ N(ν), where N is the total number of segments of the dendrimers. For amphiphilic dendrimers, DFT results show that chemical modification in the outermost generation is an effective method to drive the ends toward the periphery of the dendrimers. In particular, a conformation with a hollow interior structure could be formed for amphiphilic dendrimers with longer end spacers in a selective solvent. The resulting unimolecular micelles with a hollow core and dense shell could serve as a unique candidate for encapsulation applications, such as sustained-drug-release nanocontainers.
利用经典密度泛函理论（DFT）研究了均聚物树枝状大分子和两亲性树枝状大分子在各种溶剂中的构象，其中明确考虑了排除体积效应。对于无热溶剂中的均聚物树枝状大分子，DFT结果预测外层链段具有显著的折返行为，支持了密核模型。在不良溶剂中观察到均聚物树枝状大分子发生从线团到球状的转变。以回转半径〈Rg〉表征的树枝状大分子尺寸符合标度关系〈Rg〉∼N(ν)，其中N是树枝状大分子的链段总数。对于两亲性树枝状大分子，DFT结果表明最外层的化学修饰是驱使末端朝向树枝状大分子外围的有效方法。特别是，在选择性溶剂中，具有较长末端间隔基的两亲性树枝状大分子可形成具有中空内部结构的构象。由此产生的具有中空核和致密壳的单分子胶束可作为包封应用的独特候选物，如持续药物释放纳米容器。
