Surface Modification Of Inorganic Nanomaterials With Polymers And Its Applications

With the development of nanotechnology, many distinctive nanomaterials have been explored and attracted great attentions due to their promising applications in many fields. Among them, mesoporous silica nanoparticles and carbon nanotubes are especially glamorous because they could be used in many applications like catalysis, adsorbents, durg-delivery, semiconducting component, and molecular wires. Due to their inevitable shortcomings, we need to modify them with chemical methods. In this dissertation, different polymers were used to functionalize them with different methods. The primary results acquired are listed as follows:1. A novel pH-sensitive nanosystem based on mesoporous silica nanoparticles has been successfully prepared by employing SI-ATRP of DEAEMA. The tertiary amine in PDEAEMA is easy to get a proton to form quaternary ammonium and the polymer adopts the coil (soluble) conforma-tion in acidic solution; while in the neutral or alkaline solution it is in the collapsed (insoluble) state due to the hydrophobic interaction of polymer chains. So PDEAEMA grafted on MSNs could act as a good gatekeeper to control access to the pores via a pH-dependent open-close mechanism, which is confirmed by the well-controlled release of RhB from the mesopores through adjusting pH of the solution.2. By attaching zwitterionic sulfobetaine copolymer onto the mesoporous silica nanopar-ticles (MSNs), we successfully prepared a novel nanocontainer which could regulate the release of payloads. RAFT polymerization is employed to prepare the hybrid poly(2-(dimethylamino)ethyl methacrylate)-coated MSNs (MSN-PDMAEMA). Subsequently, the tertiary amine groups in PDMAEMA are quaternized with1,3-propanesultone to get poly(DMAEMA-co-3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate)-coated MSNs [MSN-Poly(DMAEMA-co-DMAPS)]. The zwitterionic PDMAPS component endows the nanocarrier with biocompatibility, and the PDMAEMA component makes the copolymer shell temperature-responsive. Controlled release of loaded rhodamine B has been achieved in the saline solutions.3. The one-pot synthesis of MSNs coated with reversibly cross-linked polymers has been realized via RAFT copolymerization of oligo(ethylene glycol)acrylate (OEGA) and N,N’-cystaminebismethacrylamide (CBMA) on the surface of MSN-RAFT. Since the cross-linked disulfide bond can be cleaved reversibly by redox, the cross-linked polymers could be used to control the opening and closing of the pores. Therefore, this nanocontainer could realize the drug controlled release.4. The fluorescent hyperbranched poly(amide-amine)(PAMAM)-functionalized MSNs was prepared by Michael-addition polymerization of1-(2-aminoethyl)piperazine (AEPZ) with N,N’-cystaminebisacrylamide (CBA) on the surface of amino-modified MSNs. The three dimension structure of the hyperbranched PAMAM makes itself similar to the quantum dot and can be used to cap the pores of MSNs. With the existing of Dithiothreitol (DTT), the disulfide bond could be cleaved and PAMAM would be degraded. Hence, this nanocarrier could be used to control the release of payloads. When the PAMAM was further modified with folic acid, the nanoparticles were given the targeting groups. Cell culture assay indicated that this nanocarrier had little cytotoxicity and could be easily internalized by HeLa cells.5. Selectivity for Diels-Alder cycloaddition reaction of the electron-rich diene with single-walled carbon nanotubes was first investigated. The experimental results indicated that s-SWCNTs show higher reactivity with1-aminoanthracene toward DA reaction than the m-SWCNTs. The electrophilicity of SWCNTs is a crucial factor and curvature-induced strain of SWCNTs is not the driving force in this reaction, which differs from the results obtained before about covalent modification. After further modification of polymers, the elementary separation of SWCNTs achieved.