Degrafting of Poly(poly(ethylene glycol) methacrylate) Brushes from Planar and Spherical Silicon Substrates
Degrafting of Poly(poly(ethylene glycol) methacrylate) Brushes from Planar and Spherical Silicon Substrates
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DOI：
10.1021/acs.macromol.6b01445
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发表时间：
2016-12-13
期刊：
影响因子：
5.5
通讯作者：
Klok, Harm-Anton
中科院分区：
文献类型：
--
作者：
Ataman, Nariye Cavusoglu;Klok, Harm-Anton
通过表面引发的受控自由基聚合生产的密集接枝的亲水性聚合物刷已被证明在暴露于水性介质时会发生脱接枝。这种脱接过程被认为涉及膨胀诱导的、机械化学促进的位于刷基底界面处的键的水解。虽然许多报告描述了亲水聚合物刷的脱接枝，但人们对决定这一过程的这些薄膜的关键结构参数知之甚少。本报告使用一系列通过表面引发原子转移自由基聚合 (SI-ATRP) 生产的 PPEGMA 和 PPEGMEMA 刷，研究了三个参数的影响：(i) ATRP 引发剂的化学结构，(ii) 表面接枝聚合物链的分子量，以及 (iii) 表面曲率。使用由不同 ATRP 引发剂改性的基材生长的 PPEGMA 和 PPEGMEMA 刷进行的研究表明，硅氧烷以及酯/酰胺键的水解有助于脱接枝。最后，使用 PPEGMEMA 改性二氧化硅纳米粒子的实验揭示了表面曲率的影响，并表明随着表面曲率的减小，脱接枝更加明显。
Densely grafted, hydrophilic polymer brushes produced via surface-initiated controlled radical polymerization have been shown to undergo degrafting upon exposure to aqueous media. This degrafting process has been proposed to involve swelling-induced, mechanochemically facilitated hydrolysis of bonds located at the brush substrate interface. While a number of reports have described degrafting of hydrophilic polymer brushes, only little is known about the key structural parameters of these thin films that dictate this process. Using a series of PPEGMA and PPEGMEMA brushes produced by surface-initiated atom transfer radical polymerization (SI-ATRP), this report investigates the influence of three parameters: (i) the chemical structure of the ATRP initiator, (ii) the molecular weight of the surface-grafted polymer chains, and (iii) surface curvature. Studies performed with PPEGMA and PPEGMEMA brushes grown from substrates modified with different ATRP initiators indicated that hydrolysis of both siloxane as well as ester/amide bonds contributes to degrafting. Finally, experiments with PPEGMEMA-modified silica nanoparticles revealed the influence of surface curvature and suggested that degrafting is more pronounced as surface curvature decreases.