Surface-Initiated Ring-Opening Metathesis Polymerization: A Method for Synthesizing Polymer-Functionalized Nanoparticles Exhibiting Semicrystalline Properties and Diverse Macromolecular Architectures
Surface-Initiated Ring-Opening Metathesis Polymerization: A Method for Synthesizing Polymer-Functionalized Nanoparticles Exhibiting Semicrystalline Properties and Diverse Macromolecular Architectures
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DOI：
10.1021/acs.macromol.0c01381
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发表时间：
2020-10-13
期刊：
影响因子：
5.5
通讯作者：
Hickey, Robert J.
中科院分区：
文献类型：
--
作者：
LaNasa, Jacob A.;Hickey, Robert J.
聚合物接枝纳米颗粒是设计具有最佳组分分散和增强材料性能的杂化材料的有效方法。通过开环复分解聚合（ROMP）获得的烯烃化学反应为聚合物接枝纳米颗粒提供了一条途径，这些纳米颗粒具有独特的链结构和化学功能，这是普通表面引发聚合方法难以实现的。在这里，我们展示了直径在25到140纳米之间的二氧化硅纳米颗粒表面引发的ROMP （SI-ROMP）产生的接枝聚合物链由聚降冰片烯（PNBE）、聚环二烯（PCOD）、聚乙烯（PE）和以聚环氧乙烷为侧链的瓶刷聚合物组成。此外，通过实验测量了PNBE和PCOD接枝聚合物纳米颗粒的电刷高度，并将其与预期的结垢规律进行了直接比较，从而对SI-ROMP过程中聚合物电刷的生长有了基本的了解。发现聚合物刷的拓扑结构在粒子表面附近偏离预期。根据分子量和接枝密度表征，二级链转移有利于靠近表面的聚合物网络形成，而线性链拓扑有利于远离颗粒表面的距离。本文详细介绍了成功实现具有独特拓扑结构、化学功能和热性能的聚烯烃接枝所需的SI-ROMP反应条件，这将为聚合物接枝纳米颗粒在杂化材料中的应用开辟新的途径。
Polymer-grafted nanoparticles are effective for designing hybrid materials with optimal component dispersion and enhanced material properties. The olefin chemistry accessible through ring-opening metathesis polymerization (ROMP) presents a route to polymer-grafted nanoparticles that possess unique chain architectures and chemical functionality difficult to achieve with common surface-initiated polymerization methods. Here, we show that surface-initiated ROMP (SI-ROMP) from silica nanoparticles ranging from 25 to 140 nm in diameter result in grafted polymer chains consisting of poly(norbornene) (PNBE), poly(cyclooctadiene) (PCOD), poly(ethylene) (PE), and bottlebrush polymers with poly(ethylene oxide) as the side chains. Furthermore, the brush heights of PNBE and PCOD polymer-grafted nanoparticles are experimentally measured and directly compared to expected scaling laws to present fundamental understanding into the polymer brush growth during SI-ROMP. It is found that polymer brush topology deviates from expectations near the particle surface. By the use of molecular weight and graft density characterization, it is reported that secondary chain transfer favors polymer network formation close to the surface, while linear chain topologies are favored at distances much further from the particle surface. The work presented here details the necessary SI-ROMP reaction conditions for successfully achieving polyolefin grafts with unique topology, chemical functionality, and thermal properties, which will open new avenues for polymer-grafted nanoparticles to be implemented into hybrid materials.