Cyclic vs Linear Bottlebrush Polymers in Solution: Side-Chain Length Effect
Cyclic vs Linear Bottlebrush Polymers in Solution: Side-Chain Length Effect
复制标题
DOI：
10.1021/acs.macromol.3c00362
复制
发表时间：
2023-04
期刊：
影响因子：
5.5
通讯作者：
G. Chen;E. Dormidontova
中科院分区：
文献类型：
--
作者：
G. Chen;E. Dormidontova
不同结构的洗瓶刷聚合物（BBP）在纳米医学、电子学和自修复材料等广泛的应用中引起了极大的兴趣。利用原子分子动力学模拟，我们研究并比较了水溶液中环状和线性聚（乙烯醇）-接枝-聚（环氧乙烷）（PVA-g-PEONsc）BBP 的结构和水合特性，作为 PEO 侧链长度 Nsc 的函数。我们发现，总体环状 BBP 小于相应的线性 BBP，并且随着侧链长度的增加，它们的形状从环形变为盘状再变为星状，而线性 BBP 的形状从膨胀线圈变为棒/圆柱体。环状BBP的回转半径随着侧链长度的增加而增加，其速率比线性BBP稍慢，但在长侧链的限制下遵循相同的缩放比例Rg∼Nsc0.58。对于短移植物，我们确定循环和线性 BBP 的持久长度 lp 在 lp∼Nsc0.54 依赖性后以类似的方式增加。在长侧链限制下，循环 BBP 的持久长度 (lp) 饱和，而线性 BBP 的持久长度 (lp) 则按照预期的缩放关系 lp∼Nsc15/8 强烈增加。我们提出了一个比例模型，该模型表明位于环状 BBP 内部的侧链比例取决于主链环的半径，并且随着接枝长度的增加而显着减少。对于环状和线性 BBP，PEO 侧链和水之间的氢键在主链附近有所减少，观察到局部链拉伸，同时在外围达到完全水合。总体而言，与线性 BBP 相比，环状 BBP 主链 1 nm 内的水合壳具有更高的动态稳定性。
Bottlebrush polymers (BBPs) of different architecture are of considerable interest for a broad range of applications, including nanomedicine, electronics, and self-healing materials. Using atomistic molecular dynamics simulations, we investigate and compare the structural and hydration properties of cyclic and linear poly(vinyl alcohol)-graft-poly(ethylene oxide) (PVA-g-PEONsc) BBPs in aqueous solution as functions of PEO side-chain length,Nsc. We find that overall cyclic BBPs are smaller than the corresponding linear BBPs and their shape changes from donutlike to disklike to starlike with increasing side-chain length, while linear BBPs vary in shape from an expanded coil to a rod/cylinder. The radius of gyration of cyclic BBPs increases with an increase of the side-chain length at a somewhat slower rate than the linear BBPs but follows the same scalingRg∼Nsc0.58in the limit of long side chains. For short grafts, we determine that the persistence length,lp, for both cyclic and linear BBPs increases in a similar manner following anlp∼Nsc0.54dependence. In the long side-chain limit, the persistence length (lp) of cyclic BBP saturates, while for linear BBPslpstrongly increases following the expected scaling relationlp∼Nsc15/8. We propose a scaling model that shows that the fraction of side-chains located inside the cyclic BBPs depends on the radius of the backbone ring and significantly decreases with an increase of graft length. For both cyclic and linear BBPs, the hydrogen bonding between PEO side chains and water is somewhat reduced near the backbone, where local chain stretching is observed, while reaching full hydration on the periphery. Overall, the hydration shell within 1 nm of the cyclic BBP backbone is found to be more dynamically stable compared to linear BBPs.