Studies On The Synthesis And Properties Of Organic Porous Polymers And Conductive Polypyrrole/Au Nanohybrid Materials

Recently, gold nanoparticles (Au NPs) have received much attention due to their promising application in the fields of catalysis, electrochemistry, heat treatment, biological pharmacy et al. Especially, a wide variety of methods containing physical and chemical routes were utilized to prepare Au NPs. However, Au NPs are very easy to aggregate and lose their excellent performance based on the extremely high surface energy. It is still a big challenge for exploring novel materials for the synthesis of Au hybrid nanomaterials to prevent the deactivation and improve their performances on catalysis and so on.In this thesis, on the basis of the current research status of Au NPs and our research results on functional polymer nanomaterials, we successfully synthesized some Au nanohybrid materials by using organic porous polymers and conductive polypyrrole as supports, respectively. In addition, their structure and performance were also investigated systemly. This thesis was divided into three chapters. In the first chapter, a general introduction of Au NPs, organic porous polymers and conductive polypyrrole were provided, including their synthetic methods and applications.In chapter 2, a novel method for synthesis of new thiol-functionalized organic porous polymers (SH-OPPs) with micro, meso and macroporous architecture was reported by the combination of hyper-cross-linking and molecular templating of functionalized bottlebrush copolymers. Subsenquently, Au nanohybrid materials (Au/SH-OPPs) were successfully prepared by in-situ reduction of HAuCl4 based on the strong action of gold with the thiol groups from the SH-OPPs. The structures and properties of Au/SH-OPPs were characterized by BET, TEM, TG, XRD. The results indicated that Au/SH-OPPs contained a unique trimodal micro, meso and macroporous architecture and robust organic frameworks, which has a surface area of 705 m2/g (micro/mesoporous surface area were 100 and 605 m2/g, respectively) and a pore volume of 0.88 cm3/g. The average particle size of gold nanoparticles is 3.0 ±1.0 nm, which are highly dispersed and load up to 18%. Au/SH-OPPs were able to catalyze the oxidation of benzyl alcohol with high reactivity, and without loss activity even after reused for 7 times.In chapter 3, we reported a facile method to in-situ synthesize Au@PNIPAM-b-PPy nanocomposites with thermosensitive and photothermal effects using amphiphilic poly(N-isopropylacrylamide)-block-poly(pyrrolylmethylstyrene) (PNIPAM-b-PPMS) diblock copolymers as ligands. The hydrophobic PPMS block can promote the in-situ reduction of AuCl4 to zero-valent gold and be oxidatively copolymerized with the free pyrrole monomers to form a crosslinked and conjugated polypyrrole (PPy) layer. The TEM results showed that the average particle size of gold nanoparticles are 2.3±0.5 nm and 15.0 ± 2.0 nm for Au@PNIPAM-b-PPMS and Au@PNIPAM-b-PPy, respectively. The hydrophilic PNIPAM block can produce highly thermosensitive effect. The resulting Au@PNIPAM-b-PPMS coated by thermosensitive PNIPAM layer exhibited a clear-opaque reversible transition in aqueous solution. However, the Au@PNIPAM-b-PPy nanomaterials show a strong absorption in the near infrared (NIR) region, which endowed the system excellent photothermal effect. On the basis of the PPy photothermal and PNIPAM thermosensitive effects, the above Au@PNIPAM-b-PPy nanomaterials show a reversible, soluble-precipitate transition upon the NIR irradiation on-off. This kind of Au@PNIPAM-b-PPy nanocomposite might find potential applications as photothermal reagents and temperature controllers.