Preparation Of Polymethyl Methacrylate Monolayer-protected Gold Nanoparticles And Its External Stimuli-response Investigation

Gold nanoparticles (AuNPs) have attracted continuous interest owing to theirunusual properties and potential applications in optics, catalysts, and sensors. AuNPshave a strong tendency to aggregation, usually it needs to add a stabilizer which couldmaintain the stability of the system. Polymer is used as stabilizing agent to generate astable water-soluble polymer-AuNPs composite, which have been extensively studied.AuNPs could have a new function by combination with external stimuli-responsepolymer. For example, polymers response to external stimuli such as pH andtemperature make AuNPs with controlled aggregation and dispersion properties. Surfaceplasmon resonance absorption of nano-scale gold were used in the analysis anddetection. Based on the above background and new development tendence, the contentsof the corresponding three research works are shown as follows:1) Polymethyl methacrylate monolayer-protected AuNPs (PMAA-AuNPs) werefabricated and investigated their pH response. The pH stimuli-responsive polymer, polymethacrylic was firstly obtained by RAFT polymerization of tert-butylmethacrylate(PtBMA) and then hydrolysis. Nanocomposites of AuNPs and Polymethyl methacrylatewere prepared through NaBH4in situ reduction HAuCl4in aqueous solution. Weobtained AuNPs by adjusting the ratio of PMAA to HAuCl4to2.5:1,1.25:1and0.25:1,respectively. We investigated the effect of pH on the optical properties and particle sizeof AuNPs by UV-vis spectra and TEM, the results indicated that the ratio of PMAA toHAuCl4is1.25:1, the AuNPs with good optics and controllable response. It wasinvestigated that AuNPs reversible dispersed process in the pH controlling.2)Polymethyl methacrylate monolayer-protected AuNPs pH catalytic system. It was found that the catalytic activity was responsive to pH when it is applied to the catalysisreaction of NaBH4reduction of the4-nitrophenol. It was observed that the pH wasadjusted to acidic, PMAA collapsed onto the surface of the AuNPs result in AuNPsaggregation, and reduced the catalytic activity. On the contrary, in the alkaline system,polymer chains repulsion due to electrostatic interaction can improve the catalyticactivity.3)Polymer ionic liquid monolayer-protected AuNPs anion response. Polyer ionic liquied1-ethyl3-(2-methacryloyloxy ethyl) imidazolium bromine(PMMPImb) was synthesizedusing the RAFT technique, A one-pot method utilizing the dithiobenzoate functionalizedpolymer ionic liquid was used to prepare AuNPs protected with PMMPImb. Based onthe AuNPs surface plasmon resonance absorption of anionic colorimetric detection, weexplored the colorimetric detection of CrO42-, P2O74-, I-, ATP, PF6-anion affect the colorof the solution and the changes in the absorption maxima of the surface plasmonresonance. AuNPs occur to different degrees of aggregation by TEM analysis, withbetter detection and identification effect.