Modification And Application Of SBS

The poly （styrene-butadiene-styrene） triblock copolymer （SBS）, one of the most productive and important thermoplastic elastomer, is widely used in various domains, such as footwear, impact modifiers in engineering plastics and adhesives, coating and viscosity index improver of lubricant, because of its good balance of mechanical properties along with favorable processability and recyclability. In this paper, SBS is modified, and the applications of the modified SBS were discussed. Moreover, through combined SBS with inorganic nano-materials, a series of multifuctional SBS based nanocomposites have been prepared in this dissertation.The properties of the resulting multifuctional SBS based nanocomposites were also studied. The detailed content is described as follows.（1） The photoinitiator of 4-maleimidobenzophenone （4-MBP）, which has the group of photoinitiator and double bond, were synthesized by the reaction of 4-aminobenzophenone （4-ABP） and maleic anhydride （MAH）. Then, Grafting of 4-MBP onto styrene–butadiene–styrene （SBS） triblock copolymer was carried out by free radical polymerization. The grafting ratio was evaluated by varying initiator concentrations, and the structure of grafted copolymer （SBS-g-MBP） was characterized by attenuated total reflectance infrared Fourier transform spectroscopy （ATR-FTIR）, proton nuclear magnetic resonance （1H NMR） and X-ray photoelectron spectroscopy （XPS）. The results confirmed that 4-MBP was successfully grafted onto the SBS backbone. Thermal gravimetric analyzer （TGA）, dynamic mechanical thermal analysis （DMTA）, scanning electron microscopy （SEM）, and atomic force microscopy （AFM） were used to study the thermal properties and morphology of the SBS-g-MBP. Besides, the properties of crosslinked SBS-g-MBP was studied, and through the change of content of C=C in FIIR, the degree of crosslinking was qualitatively determinated, otherwise, the max content of gelatin is about 48.9%. The degree of crosslinking was calculated by the content of gelatin. Furthermore, the thermal property of the crosslinked samples was indagated by differential scanning calorimetry （DSC） and TGA. Finally, the tests of adhesion properties indicated that the 180°peel strength, shear persistent adhesivity and tack property were in the useful range for biomedical applications.（2） Multifuctional poly（styrene-butadiene-styrene） （SBS）/SiO₂-hybridized CdTe quantum dots （QDs） nanocomposites that can emit intense fluorescence was fabricated by well dispersing CdTe QDs in a polymer matrix via a direct dispersion method. The UV-vis spectrum and fluorescence measurement showed that SBS/CdTe QDs nanocomposites exhibit good optical properties. The results of transmission electron microscopy （TEM） showed well dispersion of CdTe QDs in the SBS matrix. The results of DMTA indicated that the dynamic storage modulus （E’） and dynamic loss modulus （E’’） of the SBS all increased, but the presence of CdTe QDs leaded to an decrease of glass transition temperatures of polybutadiene （PB） and polystyrene（PS） domains. In addition, mechanical tests revealed that filled with CdTe QDs was a useful method to improve mechanical properties of the SBS. Also, the fluorescent photographs taken under ultraviolet light proved that these nanocomposites possessed good luminescence property. With the fluorescent SiO₂-hybridized CdTe QDs as nanofillers, these elastomeric nanocomposites have great potential applications in the biomedical and optical area.（3） The 4-benzoyl-N,N-dimethyl-N-（2-（2-methyl-1-oxo-2-propenyloxy）ethyl）be- -nzenemethanaminiu-mbromide （4-BBPDMAEMA） was synthesized by the reaction between 4-Bromomethyl benzophenone （4-BBP） and dimethyl amino ethyl methacrylate （DMAEMA）. A functionalized graft copolymer （SBS-g-BBPDMAEMA）, containing the group of photoinitiator, the quaternary ammonium cation and many C=C double bonds, was synthesized to modify clays such as Na+?Montmorillonite clay （MMT） for the preparation of organic-inorganic nanocomposites resins via radical photoinduced crosslinking polymerization. The structure of SBS-g-BBPDMAEMA was characterized by the FTIR and 1H NMR. Then, the SBS-g-BBPDMAEMA was used preparation of exfoliated SBS/MMT nanocomposites by UV-cross-linking of intercalation polymerization. The results from the X-ray diffraction （XRD） primarily revealed that the clay platelets should be exfoliated or completely disordered. However, the results from the TEM confirmed that a mixture of partially exfoliated and intercalated structures presented in the nanocomposites. The results of TGA indicated that the naocomposties had good thermal stability property, and testing of mechanical properties showed when the content of MMT was 5 wt%, the naocomposties had the best mechanical properties.（4） The hydroxylated styrene–butadiene–styrene tri-block copolymer （HO-SBS） was synthesized by H2O₂ and formic acid anhydrous. The pristine multi-walled carbon nanotubes （MWCNTs） were chemically oxidized by a mixture of H2SO4 and HNO3 and then reacted with thionyl chloride to functionalize them with acyl chloride groups. The HO-SBS/MWCNTs nanocomposites were prepared via covalent bond by means of the reaction between HO-SBS and MWCNTs-COCl. The resulting nanocomposites had been characterized by the testing of gel fraction and degree of swelling, Raman spectra, FTIR, SEM, TEM, DSC, TGA, and Instron mechanical tester. The results of gel fraction and degree of swelling showed that the HO-SBS/MWCNTs nanocomposites had crosslinked structure. The results of Raman spectra and FTIR indicated that there were interaction between the HO-SBS and MWCNTs. The results of SEM and TEM also showed that there were interaction between the HO-SBS and MWCNTs. The results of DSC showed that the well dispersed MWCNTs decreased its order-disorder transition temperature, and the presence of MWCNTs could lead to an increase of glass transition temperatures of PB domains. In addition, mechanical tests reveal that dispersion of MWCNTs-COCl via covalent bond in polymer matrix is a useful method to regulate mechanical properties of the HO-SBS.（5） HO-SBS with crosslinked networks was prepared using various amounts of toluene diisocyanate （TDI）. The results of gel fraction and degree of swelling showed that the sample had crosslinked structure, and the crosslinked HO-SBS exhibits high solvent resistance. The results of FTIR and the solid-state nuclear magnetic resonance （NMR） spectra confirmed that that crosslinked structure had been obtained. The results of SEM showed that the mode of fracture surfaces transmits gradually from tough fracture to brittle fracture. The results of TGA displayed that the thermal stability property of sample almost did not changed. The results of DMTA displayed the glass transition temperature of the PB domains shifted to higher temperature, but the glass transition temperature of the PB domains decreased. Mechanical test indicated that crosslinking is a useful method to regulate mechanical properties of the HO-SBS.