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arXiv 1612.03313cond-mat.soft
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无规多嵌段共聚物的微相分离

Microphase Separation in Random Multiblock Copolymers

E. N. Govorun, A. V. Chertovich

摘要:

用平均场论研究了无规多嵌段共聚物的微相分离,假定共聚物的长嵌段是强烈分离的,而短嵌段能够渗透到“外来”微区中,并在微区和界面层之间进行交换。一个双分散共聚物的嵌段只有两个尺寸(长和短)被认为是一个模型的多嵌段共聚物具有高的多分散性的嵌段尺寸。共聚物的短嵌段在微相分离中起重要作用。首先,它们向“外来”域的渗透导致在它们自己的域中形成联合长块。第二,短嵌段定位在界面上显着改变界面张力。短嵌段渗透到“外来”结构域中的可能性由乘积chi*Nsh(chi是Flory-Huggins相互作用参数,Nsh是短嵌段长度)控制。在不是非常大的chi*Nsh下,域尺寸大于由与所考虑的无规共聚物中相同的长嵌段组成的规则共聚物的域尺寸。在固定的平均嵌段尺寸下,域尺寸随着嵌段尺寸分散度的增加而增长,增长的速率取决于嵌段尺寸分布的更详细的参数。

英文摘要:

Microphase separation in random multiblock copolymers is studied with mean-field theory assuming that long blocks of a copolymer are strongly segregated, whereas short blocks are able to penetrate into "alien" domains and exchange between the domains and interfacial layer. A bidisperse copolymer with blocks of only two sizes (long and short) is considered as a model of multiblock copolymers with high polydispersity in the block size. Short blocks of the copolymer play an important role in microphase separation. First, their penetration into the "alien" domains leads to the formation of joint long blocks in their own domains. Second, short blocks localized at the interface considerably change the interfacial tension. The possibility of penetration of short blocks into the "alien" domains is controlled by the product chi*Nsh (chi is the Flory-Huggins interaction parameter, Nsh is the short block length). At not very large chi*Nsh, the domain size is larger than that for a regular copolymer consisting of the same long blocks as in the considered random copolymer. At a fixed mean block size, the domain size grows with an increase in the block size dispersity, the rate of the growth being dependent of the more detailed parameters of the block size distribution.

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