Synthesis Of End-functionalized Styrene-isoprene-butadiene Copolymer By Anionic Polymerization

The integral rubber SIBR is a new generation of solution-polymerized styrene and butadiene rubber. It has low rolling resistance and high-grip properties, and can be used in manufacturing high performance tire. SIBR also has dynamic mechanical properties and find applications in lubricating oil additive, component of bitumen, and modifing thermoplastic elastomer, etc. On the other hand, end group functionalization of SIBR can improve its properties such as polarity, surface adhesive property, anti-dirt property, low-temperature compliant, which lead to the application in the fields of aerospace industry and military supplies industry. Thus, we modified SIBR by chain end functionalization to meet specific performance requirements.In this thesis, linear random SIBR was synthesized with n-butyl lithium as initiator, tetramethylethylenediamine (TMEDA) as structure regulator. Then end-functionalized SIBR was prepared with N.N-dimethyl-aminobenzylidene-aniline (DMABA), propylene oxide, and 1,3,5-(methyl trifluoropropyl) cyclotrisiloxane (D3F) as end-capping agent. Using NMR analysis, FTIR spectroscopy analysis, and titration method, the introduction of functional groups at the polymer chain end was confirmed, and the functionalization reaction process were investigated to determine the optimum conditions of synthesis of the functionalized SIBR. The mechanical property, surface hydrophilic property, and surface adhesive property of different SIBR were examined by dynamic mechanical analyzer, contact angle analyzer, electronic tensile test and the method of properties of vulcanized rubber to metal bonding. The results showed that amino, hydroxyl end-chain modified SIBR enhanced intermolecular interaction. Tanδvalue, storage modulus, and loss modulus did not significantly increase. In contrast, tensile strength, surface hydrophilicity properties and surface adhesive properties were significantly improved. The surface of SIBR-PMTFPS display strong hydrophobic properties, and with fluoride siloxane increased, the surface contact angle became larger. Polymer of methyl trifluoro-propyl siloxane (PMTFPS) appeared at-75℃. after modified by fluoride siloxane. Tan8 increased with the increase of the soft segment PMTFPS content, while the corresponding SIBR phase's tanδdecreased at 0℃. The storage modulus of SIBR-PMTFPS decreased when the temperature increased from-75℃to 0℃, and loss modulus increased around at-75℃, but decreased at 0℃temperature region, the two regions showed the opposite trend. Mechanical properties of fluoride siloxane modified SIBR decreased, and the maximum tensile strength and elongation at break are lower. When the ratio of SIBR/PMTFPS is 50%, the maximum tensile strength is 11.8MPa, elongation at break was below 200%.