Faculty of Physics, University of Vienna, Botlzmanngasse 5, A-1090 Vienna, Austria.
J Chem Phys. 2012 Mar 7;136(9):094902. doi: 10.1063/1.3689303.
We use a standard bead-spring model and molecular dynamics simulations to study the static properties of symmetric linear multiblock copolymer chains and their blocks under poor solvent conditions in a dilute solution from the regime close to theta conditions, where the chains adopt a coil-like formation, to the poorer solvent regime where the chains collapse obtaining a globular formation and phase separation between the blocks occurs. We choose interaction parameters as is done for a standard model, i.e., the Lennard-Jones fluid and we consider symmetric chains, i.e., the multiblock copolymer consists of an even number n of alternating chemically different A and B blocks of the same length N(A) = N(B) = N. We show how usual static properties of the individual blocks and the whole multiblock chain can reflect the phase behavior of such macromolecules. Also, how parameters, such as the number of blocks n can affect properties of the individual blocks, when chains are in a poor solvent for a certain range of n. A detailed discussion of the static properties of these symmetric multiblock copolymers is also given. Our results in combination with recent simulation results on the behavior of multiblock copolymer chains provide a complete picture for the behavior of these macromolecules under poor solvent conditions, at least for this most symmetrical case. Due to the standard choice of our parameters, our system can be used as a benchmark for related models, which aim at capturing the basic aspects of the behavior of various biological systems.
我们使用标准的珠-簧模型和分子动力学模拟来研究对称线性多嵌段共聚物链及其在稀溶液中的块在不良溶剂条件下的静态性质，从接近θ条件的区域，其中链采用类似线圈的形成，到较差的溶剂条件，其中链折叠获得球状形成并且块之间发生相分离。我们选择与标准模型相同的相互作用参数，即 Lennard-Jones 流体，并且我们考虑对称链，即多嵌段共聚物由相同长度 N(A)=N(B)=N 的偶数个交替的化学不同的 A 和 B 块组成。我们展示了单个块和整个多嵌段链的常见静态性质如何反映这些大分子的相行为。此外，当链在一定范围内的 n 时为不良溶剂时，参数（例如块的数量 n）如何影响单个块的性质。还对这些对称多嵌段共聚物的静态性质进行了详细讨论。我们的结果与最近关于多嵌段共聚物链行为的模拟结果相结合，为这些大分子在不良溶剂条件下的行为提供了一个完整的图景，至少对于这种最对称的情况是如此。由于我们参数的标准选择，我们的系统可以用作相关模型的基准，这些模型旨在捕获各种生物系统行为的基本方面。
