writer：Wenjing Zhang; Jia Song; Wang Liao; Ying Guan; Yongjun Zhang; X. X. Zhu
keywords：Ag nanoparticle; fluorescent; layer-by-layer
source：期刊
specific source：Journal of Materials Chemistry C
Issue time：2013年
Fluorescent  Ag  nanoclusters  have  been  easily  generated  in  layer-by-layer  (LBL) fi lms  of  poly(vinyl
pyrrolidone)  (PVPON)  and  poly(acrylic  acid)  (PAA)  by  photo-reduction  of  Ag + ions,  which  were
previously loaded via an ion exchange mechanism. Under UV irradiation, Ag + ions were reduced to Ag
atoms by the photo-generated radicals and then aggregate to form fl uorescent nanoclusters. The Ag +
concentration plays a key role in the determination of the growth rate of Ag particles. Careful tuning of
the  Ag  loading  in  the fi lm  prevented  the  growth  of  the fl uorescent  nanoclusters  into  larger  non-
fl uorescent  nanoparticles.  Fluorescent Ag  nanoclusters can be  generated in both wet and dry fi lms.
However, the fl uorescence intensity achieved in dry fi lms is lower than that in wet fi lms because the
tight  con fi nement  of  the  polymer  network  retards  the  di ff usion  and  aggregation  of  the  photo-
generated Ag atoms. Interestingly the fl uorescence intensity can be enhanced signi fi cantly by a post-
treatment  in  water,  as  it  allows  the  Ag  atoms  to  di ff use  and  aggregate  to  form  more fl uorescent
nanoclusters. This work shows that the PVPON/PAA LBL fi lms can serve as nanoreactors that allow the
in situ generation of fl uorescent Ag nanoclusters, yielding fl uorescent Ag nanoclusters in a technically
important form, in addition to providing a simple way to control the growth of the nanoparticles.