Study On The Synthesis And Properties Of Thermo-Sensitive Water-Soluble Polymer Based On 3-Isopropenyl-α, α-Dimethylbenzyl Urethane

In this paper, the novel hydrophobic monomer, 3-isopropenyl-α,α-dimethylbenzyl urethane (Macromer), was synthesized. And the thermosensitivewater-soluble copolymers both P(AM-Macromer) and P(AM-NIPAM-Macromer)were synthesized by free radical aqueous solution copolymerization. The structuresof the two polymers were characterized via IR Spectrum and ¹H-NMR Spectrum.The influences of the reaction conditions such as reaction temperature, time,initiator concentration and monomer concentration on the performance of thepolymer solution were investigated. The effects of copolymer concentration,temperature, salt concentration and shear rate on the apparent viscosity ofcopolymer solutions were studied. The thermosensitive mechanism of copolymersolution was studied via the viscosity method, fluorescence Spectrum, oscillatoryrheological experiments, dynamic light scattering and surface tension. At last, theinfluences of concentration of SDBS, CTAB and OP-10 on both dilute andsemidilute polymer solution were studied by viscosity method and surface tension.The results show that the reaction conditions, such as reaction temperature,initiator concentration, monomer concentration and reaction time, which havenotable effect on the performance of the products are all of optimum ones. And theproperties of polymer solution such as viscosity of P(AM-Macromer) and the LCST of P(AM-NIPAM-Macromer) are all depended on the monomer ratio ofpolymerization.The solution properties of the two copolyers are strongly dependented on thequantily and sort of the inorganic salts. The copolymer solution, the apparentviscosity of which increases with the increase of salt concentration, shows perfectsalt-thickening effect and shear-thickening effect. In the three salts, NaCl, CaCl₂ andNa₂SO₄, Na₂SO₄ is of the best salt-thickening effect, but the polymer seperates outfrom the solution with higher salt concentration. P(AM-NIPAM-Macromer), whichis more hydrophobic than P(AM-Macromer), separates out from the solution withthe addition of NaCl, Na₂SO₄ ,and results in the drop of viscosity. But the polymerviscosity rise with the addition of CaCl₂.P(AM-Macromer) and P(AM-NIPAM-Macromer) are of thermosensitivety.The thickening property of P(AM-Macromer) aqueous solution is prominent withincreasing temperature. Even at low polymer concentration, the thermo-thickeningproperty is also prominent. The dynamic rehologieal experiments show that theelastic modulus(G′) is higher than the loss modulus (G″), and with the increase oftemperature, G′increases dramatically and G″decreases a little.P(AM-NIPAM-Macromer), which is different from P(AM-Macromer), is of lowcritical solution temperature, and the viscosity decreases with raising temperature.The additions of small molecules can also enhance the thermo-sensitivity ofboth polymer solutions. The apparent viscosity of P(AM-Macromer) aqueoussolution increased after the addition of NaCl, and results in the enlargement of thethickening range. P(AM-NIPAM-Macromer) aqueous solution is more sensitive toinorganic salt. The additions of salts can result in the decrease of the LCST ofP(AM-NIPAM-Macromer) solution. The addition of ionic surfactants has oppositeeffect on the LCST, as the concentration of both SDBS and CTAB increase, theLCST of polymer solution increases, but the nonionic surfactant nearly has no effecton the LCST of polymer solution.The micro-structures of aqueous solution of both P(AM-Macromer) andP(AM-NIPAM-Macromer) are related with polymer concentration and salt concentration. The hydrodynamic diameters of both polymers increase with theincrease of NaCl concentration. The dependance of hydrodynamic diameter ontemperature is related with polymer concentration. The hydrodynamic diameterdecreases when raising the temperature at low polymer concentration, And at highconcentration, hydrodynamic diameter increases when the temperature rises.The influence of different surfactants to the viscosity of polymer solution isrelated with the polymer structure, concentration and the micro-association type inthe solution. For P(AM-Macromer) copolymer, with the additions of SDBS, CTABand OP-10, the apparent viscosity of polymer solution is different at differentpolymer concentration, and the apparent viscosity increases abruptly at properconcentration of surfacant. The influence sequence of surfactants to bothP(AM-Macromer) and P(AM-NIPAM-Macromer) solution is SDBS＞CTAB＞OP-10.