Aggregation Behavior Of Lined And Branched Block Polyether At Interface

Macromolecular surfactant consists of hydrophobic group and hydrophiphilic group, whose molecular weight is about 10~3～10~6g/mol.It belongs to the research objects of macromolecular chemistry and colloid chemistry.Macromolecular surfactant has been widely used in bioinspired morphosynthesis strategy,nonmaterial synthesis,and medicine delivery.Several kinds of amphiphilic polyether copolymers have been synthesized in our laboratory,and the properties such as aggregation behavior and interfacial properties have been investigated by experimental methods and molecular simulation,such as dissipative particle dynamics(DPD)and mesoscale dynamics (MesoDyn)simulation methods.On the base of these researches,we study the interfacial dilational viscoelastic properties of serval amphiphilic block copolymer, and the influence of temperature and salt.Further more,we study the steric interaction of polystyrene sphere with adsorbed PEO-PPO-PEO copolymer by optical tweezers. The stability of polystyrene dispersion with Pluronic copolymer is determined.Finaly, the interfacial properties and aggregation behavior of the Tetronic copolyether are studied.This thesis is divided into five parts.In the first section,the recent research advances of PEO-PPO-PPO aggregation behavior in water and the influence of additives are summarized.In the second section,the interfacial dilational viscoelastic properties of several Pluronic copolymer(L64,F68,17R4,17R2)at air/water interface are investigated by interfacial dilational rheology method at low frequency.The effects of temperature and NaCl on copolymer solution are also investigated.For the above copolymer,the dialtional elasticity dominates the most in its voscoelastic property,while the dilational viscosity contributes is very low.The dilational modul of the copolymer increases with increasing of EO content.For copolymer 17R4 and L64,with similar composing but different block sequence,17R4 has a bigger dilational modul than L64 for both of the adsorption and spread layer.They show different behavior with the increase of bulk concentration.L64 has a more marked influence with temperature than 17R4.The dilational modul of 17R4 passes through a maximum value with the increase of the NaCl concentration.The dilational property of Pluronic copolymer is different from the low molecular weight surfactant such as CTAB significantly,which is determined by the different relaxation process.The interaction between Pluronic copolymer and CTAB can be reflected from the interfacial viscoelastic property. Dilational modul of the mixed films go through a maximum with the increase of CTAB con.When the concentration of CTAB is beyond its cmc,the dilational modul approach to the value of pure CTAB solution,which means the polymer interface are substituted by CTAB fully.In the third section,the effect of different Pluronic copolymer on the stability of polystyrene dispersion is investigated by the method of optical tweezers,turbidity and Zeta potential.By the method of optical tweezers,we can get the steric repulsive interaction potential between two polystyrene spheres.The results indicate when the copolymers 17R4,L64 were adsorbed onto the surface of polystyrene spheres,the interaction potentials are reduced a little compared with the pure polystyrene system. 17R4 has a more notable effect on the reduction of potential function than L64.But for copolymer F127 with bigger molecular weight and more EO content,the interaction potential was increased markedly.In another word,F127 can stabilize the polystyrene dispersion while the other two can not.From the turbidity of the polystyrene/copolymer mixture,17R4 and L64 can accelerate the sedimentation rate of the polystyrene dispersion,while for mixture of polystyrene/F127 solution,the turbidity keep the constant for quite a few hours,which means stabilization effect occurred.From the change of Zeta potential of the polystyrene vs the copolymer concentration,we get the thickness of the adsorption layer by the double electric layer model.In the fourth section,the interfacial property and aggregation behavior of branched Tetronic polyether solution are studied.For T1107 and F127,the latter is more efficient in reduction of water surface tension.The surface tension isotherm of the Tetronic polyether water solution also show two inflexion.The rise of temperature can induce the formation of micelle.The pH value of Tl107 solution has a major effect on the interfacial viscoelastic property.The surface tension of T1107 water solution increase with the decreasing of pH,While the dilational moduls and elasticity decrease.The rheology of T1107 water solution is related with its concentration and temperature.The gelation temperature of the T1107 solution is lower than F127 because of its branched structure.T1107 can interact with SDS by hydrophobic interaction.In the fifth section,the inclusion complexes between several Tetronic polyethers and cyclodextrin are investigated.β-cyclodextrin can form supermolecular pseudopolyrotaxanes with branched polyether T90R4,AP432 and SF321.The formation rate depends on the length of the PPO block length,the molecular weight and molecular weight distribution of the polymer.IR and XRD research results all prove the formation of the inclusion complexes which adopted column structure.The results of the ~1HNMR indicate theβ-cyclodextrin cover on the PPO block.The ratio between the PPO block andβ-cyclodextrin is bigger than 2,which mean someβ-cyclodextrin slide off the polymer chain.TGA results show that the therm-stability of both polyether andβ-cyclodextrin are enhanced.They can interact with each other by Van de wall force and hydrogen bond between the borderβ-cyclodextrin molecules.The chief characteristics of this thesis are as follows:1.The interfacial dilational viscoelastic properties of Pluronic copolymer at air/water interface are studied systemically.The effect of temperature and salt concentration are also included.These studies not only enrich the research of the polymer interracial rheology,but also provide comprehensive data for the interracial dynamic property and relaxation process of the Pluronic copolymer.2.Optical tweezers are used to investigate the effect of the Pluronic copolymer on the stability of polystyrene dispersion.We can get the interact potential between two polystyrene spheres before and after the polymer was adsorbed.Combined with the turbutidy and Zeta potential,we get the consistent conclusions.3.A novel kind of supermoleculars pseudopolyrotaxanes between branched polyether andβ-cyclodextrin were prepared and characterized,which enrich the category of polyrotaxanes.