Abstract Polymer brushes can be useful as small-scale reactors for the controlled synthesis of nanoparticles, an approach which is gaining increasing interest. In this context, chemical crosslinking of polymer brushes could be considered as a viable approach to control the size and size distribution of the formed nanoparticles. Here we describe the application of Positron Annihilation Spectroscopy (PAS) for the characterization of crosslinked polymer brushes (brush-gels). Poly(hydroxyethyl methacrylate) (PHEMA) brushes were obtained on silicon substrates by means of a surface-initiated atom transfer radical polymerization (SI-ATRP). Crosslinking was achieved during the polymerization by adding different amounts of diethyleneglycol dimethacrylate (DEGDMA) as a difunctional monomer. The resulting brushes, both un- and crosslinked, were then post-modified with carboxylic acid groups, allowing the in situ synthesis of silver nanoparticles after ion exchange with silver nitrate and reduction with sodium borohydride. The detailed characterization of such systems is notoriously challenging and PAS proved to be an effective, non-invasive technique to acquire insight on the structure of the brushes and of their nanoparticle composites.

中文翻译：

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通过正电子湮没光谱研究交联聚合物刷（刷凝胶）的结构

摘要 聚合物刷可用作控制纳米粒子合成的小型反应器，这种方法越来越受到关注。在这种情况下，聚合物刷的化学交联可以被认为是控制形成的纳米粒子的尺寸和尺寸分布的可行方法。在这里，我们描述了正电子湮没光谱 (PAS) 在表征交联聚合物刷 (刷凝胶) 中的应用。聚（甲基丙烯酸羟乙酯）（PHEMA）刷是通过表面引发的原子转移自由基聚合（SI-ATRP）在硅基板上获得的。在聚合过程中通过添加不同量的二甲基丙烯酸二甘醇酯 (DEGDMA) 作为双官能单体实现交联。由此产生的刷子，无论是未连接的还是交联的，然后用羧酸基团进行后修饰，在与硝酸银离子交换并用硼氢化钠还原后原位合成银纳米颗粒。众所周知，此类系统的详细表征具有挑战性，并且 PAS 被证明是一种有效的非侵入性技术，可以深入了解刷子及其纳米颗粒复合材料的结构。