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arXiv 2209.02097cond-mat.softcond-mat.stat-mech
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嵌段共聚物打结环的热性能

On the thermal properties of knotted block copolymer rings

Neda Abbasi Taklimi, Franco Ferrari, Marcin Radosław Piątek, Luca Tubiana

摘要:

采用Wang-Landau MC算法,在简单立方晶格上研究了含两种单体$A$和$B$的粗粒打结聚合物在溶液中的涨落热性质.这些结具有比由均聚物形成的结更复杂的相图,包括可能存在的亚稳态。考虑两种不同的设置:i)离子溶液中的带电嵌段共聚物,和ii)具有上述$A$单体和低于θ点的$B$单体的中性共聚物。提供了比热容图中观察到的峰的精确解释。鉴于在医学和智能材料的构建中的可能应用,还表明可以通过改变其单体构型和拓扑结构来调节共聚物环的行为。我们发现,最稳定的紧凑的状态是由带电的共聚物,其中非常短的链段与$A$单体交替短链段与$B$单体。在这样的结中,从致密状态到膨胀状态的转变非常快,导致在非常高的温度下出现的比热容的窄且高的峰值。拓扑结构的影响允许调节打结聚合物环的回转半径,并增加或降低所观察到的系统的相变或重排发生的温度。虽然我们观察到一般淡出的拓扑结构的影响,在较长的聚合物,我们的模拟已经捕捉到一些例外,这条规则。

英文摘要:

The thermal properties of coarse grained knotted polymers containing two kinds of monomers $A$ and $B$ fluctuating in a solution are investigated on a simple cubic lattice using the Wang-Landau MC algorithm. These knots have a more complex phase diagram than knots formed by homopolymers, including the possible presence of metastable states. Two different setups are considered: i) charged block copolymers in a ion solution and ii) neutral copolymers with the $A$ monomers above and the $B$ monomers below the theta point. A precise interpretation of the peaks observed in the plots of the specific heat capacity is provided. In view of possible applications in medicine and the construction of intelligent materials, it is also shown that the behavior of copolymer rings can be tuned by changing both their monomer configuration and topology. We find that the most stable compact states are formed by charged copolymers in which very short segments with $A$ monomers are alternated by short segments with $B$ monomers. In such knots the transition from the compact to the expanded state is very fast, leading to a narrow and high peak in the specific heat capacity which appears at very high temperatures. The effects of topology allow to tune the radius of gyration of the knotted polymer ring and to increase or decrease the temperatures at which the observed phase transitions or rearrangements of the system occur. While we observe a general fading out of the influence of topology in longer polymers, our simulations have captured a few exceptions to this rule.

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。

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