Frisch Hendrik, Mundsinger Kai, Poad Berwyck L J, Blanksby Stephen J, Barner-Kowollik Christopher
Centre for Materials Science , School of Chemistry and Physics , Queensland University of Technology (QUT) , 2 George Street , Brisbane , QLD 4000 , Australia . Email:
Central Analytical Research Facility , Institute for Future Environments , Queensland University of Technology (QUT) , 2 George Street , Brisbane , QLD 4000 , Australia.
Chem Sci. 2020 Feb 12;11(10):2834-2842. doi: 10.1039/c9sc05381f. eCollection 2020 Mar 14.
We exploit the wavelength dependence of [2 + 2] photocycloadditions and -reversions of styrylpyrene to exert unprecedented control over the photoreversible polymerization and topology of telechelic building blocks. Blue light ( = 460 nm) initiates a catalyst-free polymerization yielding high molar mass polymers ( = 60 000 g mol), which are stable at wavelengths exceeding 430 nm, yet highly responsive to shorter wavelengths. UVB irradiation ( = 330 nm) induces a rapid depolymerization affording linear oligomers, whereas violet light ( = 410 nm) generates cyclic entities. Thus, different colors of light allow switching between a depolymerization that either proceeds through cyclic or linear topologies. The light-controlled topology formation was evidenced by correlation of mass spectrometry (MS) with size exclusion chromatography (SEC) and ion mobility data. Critically, the color-guided topology control was also possible with ambient laboratory light affording cyclic oligomers, while sunlight activated the linear depolymerization pathway. These findings suggest that light not only induces polymerization and depolymerization but that its color can control the topological outcomes.
我们利用苯乙烯基芘的[2 + 2]光环化加成和逆转反应对波长的依赖性，以前所未有的方式控制遥爪结构单元的光可逆聚合反应及其拓扑结构。蓝光（λ = 460 nm）引发无催化剂聚合反应，生成高摩尔质量聚合物（Mw = 60 000 g/mol），这些聚合物在波长超过430 nm时稳定，但对较短波长高度敏感。UVB辐射（λ = 330 nm）诱导快速解聚，生成线性低聚物，而紫光（λ = 410 nm）则生成环状聚合物。因此，不同颜色的光可实现通过环状或线性拓扑结构进行的解聚反应之间的切换。质谱（MS）与尺寸排阻色谱（SEC）以及离子淌度数据的相关性证明了光控拓扑结构的形成。至关重要的是，在实验室环境光下也可以实现颜色引导的拓扑结构控制，从而生成环状低聚物，而阳光则激活线性解聚途径。这些发现表明，光不仅能引发聚合和解聚反应，而且其颜色可以控制拓扑结构的结果。
