Simulations of sphere-forming diblock copolymer melts
Simulations of sphere-forming diblock copolymer melts
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DOI：
10.1103/physrevmaterials.6.095602
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发表时间：
2022-09
影响因子：
3.4
通讯作者：
A. Chawla;F. Bates;K. Dorfman;D. Morse
中科院分区：
文献类型：
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作者：
A. Chawla;F. Bates;K. Dorfman;D. Morse
分子动力学模拟用于研究熔体的不对称球形成两个显着不同的值的不变聚合度，3820和960的二嵌段共聚物。在这两个系统中，对应于降低温度的参数的变化导致胶束在临界胶束温度（CMT）和结晶在较低的有序-无序转变温度（ODT）的外观。CMT在模拟中可通过具有强烈隔离的核心区域的大型集群的出现来识别，但在适度的系统上的散射实验中没有同样清晰的签名。在CMT（其中Flory-Huggins参数和聚合度）处的产物值与SCFT对ODT的预测值接近，而在实际ODT处的产物值较大，且随聚合度的减小而增大。胶束表现出显着的和可比的分散性聚集数在结晶和液相附近的ODT。液相和晶相都表现出瞬态二聚体，其由相邻的球形胶束对组成，所述球形胶束具有通过芯块材料的桥连接的芯。
Molecular dynamics simulations are used to study melts of asymmetric sphere-forming diblock copolymers with two significantly different values of the invariant degree of polymerization,3820 and 960. In both systems, changes in parameters that correspond to decreasing temperature lead to the appearance of micelles at a critical micelle temperature (CMT) and crystallization at a lower order-disorder transition temperature (ODT). The CMT is identifiable in simulations by the appearance of large clusters with a strongly segregated core region, but has no equally clear signature in scattering experiments on systems of modest. The value of the productat the CMT (whereis the Flory-Huggins parameter andis degree of polymerization) is close to that predicted by SCFT for the ODT, while the value at the actual ODT is larger and increases with decreasing. Micelles exhibit significant and comparable dispersity in aggregation number in the crystalline and liquid phases near the ODT. Both the liquid and crystal phases exhibit transient dimers consisting of pairs of neighboring spherical micelles with cores connected by a bridge of core-block material.