Design, Synthesis And Properties Of Organosilicon Modified Polyurea/polyurethanes

Organosilicon is a kind of inorganic-organic hybrid material with excellent high and low temperature resistance, weather resistance, water resistance, electrical insulation, low surface energy and biological inertia, etc. But low mechanical strength and poor adhesion property of organosilicon limit its widespread use. Polyurea/polyurethane (PU), featured with the repeating urethane or urea groups in its backbone, is a class of polymer materials with wide applications due to its excellent mechanical strength, good wear resistance, high elasticity, chemical resistance, and high reactivity, etc. However, its disadvantages such as bad water and heat resistance restrict its application. Silicone-modified polyurethanes (SPU) combining advantages of organosilicon and PU, should exhibit a better water resistance, higher thermal stability, and lower surface energy than PU and should display better adhesion and better mechanical properties than organosilicon. Based on the novel phenyl polysiloxane macromonomer, in this thesis, we designed and synthesized four different series of SPUs, including moisture curing SPUs, UV-curing SPUs, waterborne SPUs and UV-curing waterborne SPUs.In chapter one, the current research progress in SPUs was reviewed, and then the designed strategies and research topics were proposed.In the second chapter, two kinds of secondary amine terminated phenyl polysiloxane macromonomers (PMPS-N) and another kind of secondary amine terminated polydimethylsiloxane macromonomer (PDMS-N) were designed and synthesized, and then characterized by FT-TR, 1H NMR and 13C NMR. Based on the macromonomers, three series of moisture-curable SPU prepolymers were prepared. SEM, AFM and DSC results showed even the phenyl polysiloxane content reached up to 40 wt.%, the obvious phase separation did not appear in phenyl polysiloxane modified SPUs. Therefore, phenyl polysiloxane could effectively avoid phase separation, which usually appeared in polydimethylsiloxane SPUs systems. Furthermore, the introduction of PMPS-N macromonomers could modify surface property and form some special voids. The size and amount of voids increased with the increase of the content of PMPS-N. A series of comparative experiments revealed the cause for the formation of voids. Results of tensile testing, water contact angle, water absorption rate and TGA analysis showed that the prepared moisture-cured SPU materials exhibited excellent mechanical strength, thermal stability and water resistance.Chapter three provided a strategy to obtain a series of UV-curable, secondary amine terminated phenyl polysiloxane macromonomers (P1s and P2), and then prepared the UV-curable SPU prepolymers (SPUAs). The results of kinetic study by real time Fourier Transform infrared spectroscopy showed that all SPUAs exhibited fast photopolymerization rate. The water angle and water absorption rate tests revealed their hydrophobic surfaces and very good water resistance. SEM results demonstrated that UV cured SPUAs showed a similar surface morphology in comparison to moisture cured SPUs. Tensile strength tests indicated that UV curing mode improved the mechanical properties of SPUs. TGA analysis results evidenced that the introduction of phenyl polysiloxane increased the thermal stability without phase separation.In chapter four, series of silicone modified polyurethanes latexes (WPUs) featured with small size and narrow distributed particles and low viscosity were prepared by PMPS-N and polyether polyol as the mixed soft segments. The effect of R value, type of soft segments, type and content of silicone, and content of hydrophilic parts on the affect rheological properties of the prepared latexes was studied. Results showed that the introduction of polysiloxane and polyether polyol largely decreased the particle size and the distribution of WPUs latex. The viscosity of latex, with a typical behavior of Newtonian fluids, decreased with the increase of polysiloxane content. The properties of the thermal solidifying films of WPUs were investigated by ATR-FTIR, SEM, contact angle, water absorption, and TGA analysis. Results indicated that the introduction of polysiloxane largely improved the water repellency, thermal stability and water contact angles.In the fifth chapter, two series of UV curable waterborne SPUs latexes (WU-WPUs) were designed and prepared. The WU-WPUs latexes had larger particle size and broader particle distribution in comparison to WPU latex. The impacts of R value and content of silicone to particle size and distribution, rheological properties of the prepared latexes were studied. Results showed that latexes showed very good comprehensive performance with R to be between 1.2 and 1.3, and with silicone content to be between 10 wt.%and 16 wt.%. UV-WPUs films exhibited the similar surface morphology of WPU but with higher mechanical strength, which were as high as those of SPUAs. Among them, the tensile strength of UV-WPU2-2 could reach as high as 9.1 MPa.