| Since the discovery of carbon nanotubes, its unique shape and structure has attractedmany researchers to explore its new performance. However, due to carbon nanotubes withhigh specific surface area and strong van der Waals force makes it very easy to agglomerate,leading to carbon nanotubes almost insoluble in any solvent. In addition, due to its specialgraphene structure, carbon nanotubes can not be dispersed in the polymer and other materials,which greatly limit its application fields. Therefore, carbon nanotubes should be modified toimprove its dispersibility in solvents and the polymers, in order to meet the applicationrequirements.Hydrophilic segments and hydrophobic segments of amphiphilic macromolecular can bearranged in the same molecular chain by a particular way, and its biggest feature is the abilityto self-assembly behavior under certain conditions. Amphiphilic macromolecular can form avariety of ordered nano-phasestructure, such as spherical, rod-like, vesicles and compositemicelles formed by small micelles. According to the unique property of the amphiphilicmacromolecular, its molecular chains and self-assembled micelles can be used to modifycarbon nanotubes, and the prepared nanocomposites have many excellent performances in thefield of coatings and other potential application fields. However, the construction unit of theresearch area is block polymer. Because of its synthesis is relatively difficult, which limitstheir large-scale applications. Compared with block amphiphilic macromolecules, Non-blockamphiphilic macromolecules is simple and easy to obtain, rich source, and have morepotential application value.The paper design and synthesis a series of non-block amphiphilic macromolecules tomodify carbon nanotubes base on non-covalently interaction. The application in the functionalcoatings was researched, and the contents are divided into the following sections:(1) Carbon nanotubes were modified by water-soluble photosensitive α-cyclodextrin and itsapplication in sensor coatingsFirst, using epichlorohydrin as the bridged unit, water-soluble α-cyclodextrin (α-CD)was introduced to modify7-hydroxy-4-methylcoumarin and prepare α-CD-C. α-CD-C wascharacterized with1H-NMR and HPLC-MS. The photo-dimerization experiment showed thatα-CD-C could photo-dimerize upon365nm irradiation, and then photo-de-crosslink upon thesubsequent254nm irradiation. Next, α-CD-C was used to disperse carbon nanotubes in water.Transmission electron microscope (TEM) and scanning electron microscope (SEM)demonstrated that carbon nanotubes was successful modified by α-CD-C, and its applicationin sensor coatings were studied.(2) Carbon nanotubes were modified by amphiphilic macromolecular P(St/VM-co-MA) toprepare sensor coatingsPhotosensitive amphiphilic macromolecular P(St/VM-co-MA) was synthesized withstyrene (St), styrene-containing photosensitive monomer7-(4-vinylbenzyloxy)-4-methyl coumarin (VM) and maleic anhydride (MA) via free radical copolymerization. The structureof P(St/VM-co-MA) was characterized by1H nuclear magnetic resonance (1H-NMR).P(St/VM-co-MA) could form micelles in the selective solvent N, N-dimethylformamide(DMF)/H2O. UV-Vis spectrum indicating the photodimerization reaction of P(St/VM-co-MA)micelles. The multi-wall carbon nanotubes (MWCNTs) were encapsulated in the formedmicelles through non-covalent interactions. The formed structures were novel nanocompositeswhich were confirmed by TEM, SEM, and Raman spectroscopic analysis. The results showedthat the dispersion performance of the obtained micelle-encapsulated carbon nanotubes inwater was greatly improved compared to the pure carbon nanotubes. From the TEMobservation, the individual MWCNTs structure and the uniform polymer coating around thesurface of MWCNTs were seen after crosslinking. In addition, the prepared materials wereused in sensor coating, the response and recovery properties of the coatings were measured. Itwas showed that the resistance of sensors inereased with increasing content of gas. Amodified glassy-carbon (GC) electrode by P(St/VM-co-MA) has been successfully developedsensor coatings for determination of dopamine (DA) in the presence of ascorbic acid (AA). Itcan be concluded from the result that the respond changes within different concentration ofDA. Interference from AA was effectively eliminated and the detection limit was5×10-8mol/L.(3) Dispersion of carbon nanotubes through electro-active photo-senstive amphiphilicmacromolecular and its application in sensor coatingsP(VM/VCz-co-MA) was synthesized through free radical copolymerization with twostyrene derivative monomers and maleic anhydride. The amphiphilic macromolecular canself-assemble into micelle (EACM) which could efficiently disperse MWCNTs in aqueoussolution. The EACM/MWCNTs hybrid was characterized by UV-Vis, TEM、SEM、TGA andRaman. Experimental results show that the dispersion capacity of macromolecular enhancedwith the increasing content of carbazole group. Then, dispersion of carbon nanotubes wereused to product gas sensor and electrochemical sensors. Dopamine sensors were fabricatedusing glassy carbon electrode (GCE) modified with EACM/MWCNTs hybrid. The carbazolemoieties in macromolecular chains could electro-polymerize with increasing CV cycles, thuscreating large conjugated system and forming a conducting surface on MWCNTs. Ourinvestigations indicate that the peaks of dopamine (DA) and ascorbic acid (AA) wereoverlapped without carbazole moieties electro-polymerized in DPV measurement. In contrast,the peak currents were amplified about ten times and the peaks of DA and AA were separatedwith carbazole moieties electro-polymerized. Such results showed that the EACM/MWCNTsmodified GCE could serve as an efficient biosensor for low-concentration DA detecting in thepresence of high-concentration AA.(4) Branched styrene-maleic anhydride copolymer modified carbon nanotubes and theirapplications in sensor coatings and superhydrophobic coatingsBranched Polystyrene maleic anhydride (BPSMA) were synthesized through the method ofMCTBP with maleic anhydride(MA), styrene (St), and4-vinyl benzyl thiol (VBT) as branched monomer and AIBN as the initiator. The successful synthesis of BPSMA wasconfirmed by a triple detection systems including gel permeation chromatography (GPC),multiangle laser light scattering (MALLS), and differential viscosity (DV) detectors, as wellas thermal analysis (differential scanning calorimetry). The influence of more inventory andpolymerization time on structure and properties of BPSMA were studied. The influence ofcontent of branched monomer and polymerization time on self-assembly behavior of BPSMAwas researched. The particle size and morphology of the self-assembled micelles werecharacterized by DLS and TEM. Pristine multiwalled carbon nanotubes (MWCNTs) werenon-covalently modified by an organic-inorganic hybrid of the BPSMA and silica with theexistence of γ-aminopropyl-triethoxysilane. The modified MWCNTs were mixed withtetraethyl orthosilicate in ethanol, coated with a fluoroalkylsilane, and then heat treated toobtain the superhydrophobic antistatic coatings. Scanning electron microscopy (SEM) showedthat the coatings have a micrometer-and nanometer-scale hierarchical structure similar to thatof lotus leaves with high water contact angles (>170°). In addition, the relationship betweencontent of MWCNTs, cure temperature and the properties of the coatings were investigatedsystematically. The results showed that the hydrophobic and conductivity of the coating wasincreased with the increasing content of carbon nanotubes, the stability of the coating wasbetter with the increasing curing temperature, when the content of carbon nanotube was10wt%, the contact angle was180°, and the resistance was7.2×10~5.In summary, a series of amphiphilic macromolecules were synthesized to modify carbonnanotubes, and their application in the functional coatings was studied. A series of quite newfindings were obtained. |
PDF Full Text Request