pH-responsive poly(4-vinylpyridine) (P4VP) grafted cellulose nanocrystals (P4VP-g-CNC) were prepared by Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) and subsequently used to stabilize gold nanoparticles (Au NPs) as efficient and recyclable nanocatalysts for the reduction of 4-nitrophenol (4NP). The presence of P4VP brushes on the CNC surface controlled the growth of Au NPs yielding smaller averaged diameter compared to Au NPs deposited directly on pristine CNC. The catalytic performances of pristine Au NPs, Au@CNC and Au@P4VP-g-CNC were compared by measuring the turnover frequency (TOF) for the catalytic reduction of 4NP. Compared to pristine Au NPs, the catalytic activity of Au@CNC and Au@P4VP-g-CNC were 10 and 24 times better. Moreover, the Au@P4VP-g-CNC material could be recovered by flocculation at pH > 5, and the recycled nanocatalyst remained highly active.

中文翻译：

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聚（4-乙烯基吡啶）嫁接的纤维素纳米晶体稳定的金纳米粒子作为高效和可回收的催化剂

通过表面引发的原子转移自由基聚合（SI-ATRP）制备pH响应的聚（4-乙烯基吡啶）（P4VP）接枝的纤维素纳米晶体（P4VP -g- CNC），随后用于稳定金纳米颗粒（Au NPs）的效率以及用于还原4-硝基苯酚（4NP）的可回收纳米催化剂。与直接沉积在原始CNC上的Au NP相比，CNC表面上P4VP刷的存在控制了Au NP的生长，产生的平均直径更小。通过测量周转频率（TOF）对4NP的催化还原作用，比较了原始Au NP，Au @ CNC和Au @ P4VP -g-CN的催化性能。与原始Au NPs相比，Au @ CNC和Au @ P4VP -g-的催化活性CNC分别提高了10倍和24倍。而且，Au @ P4VP -g- CNC材料可通过在pH> 5时絮凝来回收，而回收的纳米催化剂仍保持高活性。