arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2202.01039cond-mat.softphysics.chem-phphysics.comp-ph
收藏

聚合物自由能对Polymer接枝纳米粒子多晶型的影响

Impact of Free Energy of Polymers on Polymorphism of Polymer-Grafted Nanoparticles

Masanari Ishiyama, Kenji Yasuoka, Makoto Asai

摘要:

我们专注于聚合物接枝纳米颗粒(PGNP)。PGNP由两个不同的层组成:纳米颗粒的硬核和表面上接枝聚合物的软冠。预测具有这两个不同层的PGNP将具有与星形聚合物和硬球类似的行为。PGNP之间的相互作用强烈地依赖于它们的接枝密度和接枝聚合物链的长度N。因此,PGNP可以表现出多态性。此外,由于接枝聚合物的缠结,预期由PGNP制成的晶体将在结构上是坚韧的。使用分子动力学模拟探索PGNP的晶体多晶型。我们成功地发现FCC/HCP和BCC晶体取决于接枝聚合物链的长度。当N很小时,PGNP表现得像硬球。所形成的晶体以FCC/HCP结构排列,很像在Alder转变中观察到的相变。当N足够大时,接枝聚合物自由能的增加不再可以忽略。因此,在这些系统中形成的晶体以BCC结构排列,其具有比FCC/HCP更低的密度。当N不太小或太大时,当PGNP的浓度较低时观察到FCC/HCP结构,但当PGNP的浓度随着系统的压缩而变高时发生相变。同样,接枝聚合物的自由能的增加不能再被忽略,并且晶体以BCC结构排列。此外,可以揭示,PGNP晶体的晶格间距可以通过链长容易且广泛地控制。这些结果应该发挥重要作用,在许多未来的模拟和实验研究的PGNP晶体。

英文摘要:

We focus on polymer-grafted nanoparticles (PGNP). A PGNP is composed of two different layers: the hard core of a nanoparticle and the soft corona of grafted polymers on the surface. It is predicted that PGNPs with these two distinct layers will have similar behaviors as star polymers and hard spheres. The interaction between PGNPs strongly depend upon their grafting density and the length of the grafted polymer chains, N. Thus, PGNP may exhibit polymorphism. Moreover, it is expected that crystals made from PGNPs will be structurally tough due to the entanglement of grafted polymers. The crystal polymorph of PGNP is explored using molecular dynamics simulations. We succeeded in finding FCC/HCP and BCC crystals depending on the length of the grafted polymer chain. When N is small, PGNPs behave like hard spheres. The crystals formed are arranged in FCC/HCP structure, much like the phase transition observed in an Alder transition. When N is large enough, the increase in the free energy of grafted polymers can no longer be neglected. Thus, the crystals formed in these systems are arranged in BCC structure, which has a lower density than FCC/HCP. When N is not too small or large, FCC/HCP structures are observed when the concentration of PGNPs is low, but a phase transition occurs when the concentration of PGNPs becomes higher with the compression of the system. Again, the increase in free energy of grafted polymers can no longer be neglected and the crystals arrange themselves in a BCC structure. Also, it can be revealed that the lattice spacing of PGNP crystals can be controlled easily and widely by the chain length. These results should play an important role in many future simulations and experimental studies of PGNP crystals.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑