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Electrically neutral polymer with non-ionic surfactant TX - 100 molecular assemblies interaction studies

Author: GeLingLing
Tutor: GuoRong
School: Yangzhou University
Course: Physical and chemical
Keywords: Surfactant system Lamellar liquid crystal Reverse micelles Macromolecule Nonionic surfactant Triblock copolymers Composite Micelle surface Interaction Micellar structure
CLC: O631.3
Type: PhD thesis
Year: 2009
Downloads: 217
Quote: 2
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Unique hydrophilic and lipophilic nature of the amphiphilic surfactant molecules in solution can spontaneously aggregate to form micelles, vesicles, microemulsion and liquid crystal Molecular Assemblies. Organized assembly of these molecules has a unique micro-environment of the polar or non-polar scale, at least in the direction of the one-dimensional nano-scale, organized assembly of these molecules is an important form of material existence, therefore, surfactants The agent plays an important role in the life sciences, materials science, energy science, as well as many modern high-tech development. Mixed system of surfactant and polymer, especially a water-soluble polymer blend system, the performance of a single surfactant or polymer systems do not have the peculiar nature of the polymer and the macroscopic properties of the mixed system can be changed through the design and molecular structure, composition and chain length to be adjusted to meet the specific field of application. At present, the surfactant and polymer mixed system in oil exploration, textile dyeing and finishing industry, household chemicals, nanomaterials preparation and pharmaceutical industry has a wide range of applications. The study of the interaction between the surfactant and polymer are more and more attention, and continue to develop in depth, that is gradually in-depth study of the macroscopic properties to the detection of micro-structure, from the summary of the development of the empirical regularity to the molecular and sub-molecular level. This thesis work is based on the above-described background, and the commencement of the development trend research with non-ionic surfactant, optional water-soluble polymer of polyethylene glycol and polyoxyethylene - polyoxypropylene - polyoxyethylene block copolymer, micelles, microemulsions and lamellar liquid crystal interaction mechanism. Polymer and the micelles, microemulsions, liquid crystal from a molecular level to clarify the role of model to ScS polymer molecular chain length, composition, temperature and other physical and chemical conditions of the microscopic structure and the nature of the polymer / surfactant complexes, mainly the following aspects: 1. fluorescence non-radiative energy transfer (FRET), nuclear magnetic resonance (NMR), dynamic light scattering (DLS), freeze-fracture electron microscopy (FF-TEM) study of a non-ionic surfactant Triton X-100 (TX-100) / Poly (ethylene glycol) (PEG) composite microstructure. The results showed that: TX-100 and pyrene better donor - receptor pairs, TX-100 molecules of different molecular weight PEG Add the increase in the average distance between the benzene ring and pyrene molecules, indicating that the composite TX -100 micelle structure than the free micelles loose the micelle changes in the structure and independent of the molecular weight of PEG. And the morphology of the composite vary depending on the PEG molecular weight (MW): The smaller molecular weight PEG (MW lt; 2000 Dalton) into the TX-100 micelles hydrophilic base or cover the surface of the micelle, the formation of the spherical composite ; the larger molecular weight PEG (MW gt; 2000 Dalton) multiple micelle role, the formation of coral-like clusters. In addition, the elevated temperature of the system is conducive to the formation of TX-100/PEG composite, and straight chain alcohols do not affect the formation of complexes. 2 In the nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and isothermal titration calorimetry (ITC) investigated the interaction of the non-ionic surfactant TX-100 with the block copolymer F127. The study results showed that F127 synergies exist between the TX-100 form TX-100/F127 compound, its micro-structure can be adjusted by the temperature and the concentration of TX-100. The micro-structure of the compound with a transition temperature (F127 = 20 mg / mL): in the low-TX-100-concentration region (LT; 9.42 mm), 5 ° C when F127 chain adsorption in the TX-100 micelle surface is formed to the TX-100 micelle composite body, the temperature rises, the disintegration of the TX-100 Micellar and insert F127 Micelles formed composite F127 Micelles body; medium TX-100 concentration region (9.42-94.85 mM), with significantly elevated temperature F127/TX-100 composite structure from the disintegration of the body changes to F127 for the TX-100 as the main body; high TX-100 concentration region (gt; 157.57 mM), F127 and TX-100. Interaction reached saturation TX-100 free micellar system. The micro-structure of the compound with the TX-100 concentration changes: in the low temperature (5-10 oC), F127 monomers adsorbed onto TX-100 micelle forming complexes; within the range of 15-25 oC, TX- 100 Add promoting F127 monomer aggregation, and TX-100 is formed composite body F127; within the 30-40 ° C range, a small amount of TX-100 inserted in the form of a monomer F127 Micelles formed body F127 composite, with an increase in TX-100 concentration, F127 micelle disintegration, the composite body TX-100 Micellar. Dynamic light scattering (DLS), nuclear magnetic resonance (NMR), fluorescent probes, and infrared spectroscopy study of polyethylene glycol (PEG) structure of the reverse micelles of TX-100 / cyclohexane / H2O system . The results showed that: TX-100 cyclohexane in the formation of non-spherical reverse micelles, the temperature rises, the reverse micelle into spherical. The PEG400 dissolved in the core of the reverse micelles, and replace bound water and TX-100 EO chain effect, induced reverse micelles fuse to form larger clusters. PEG longer the molecular chain, the better, the smaller the particle size of the reverse micelles induced fusion of reverse micelles. However, the solubility of PEG in reverse micelles decreases with increasing molecular weight. 4 nuclear magnetic resonance (NMR), polarized optical microscopy (POM), small-angle X-diffraction (SXRD) and freeze-fracture electron microscopy (FF-TEM) study the the PEG system TX-100/n-C8H17OH/H2O layered LCD positioning (1alpha), and PEG induced Lα micro-structural changes in the phase transition process. The nonionic surfactant system the \PEG amphiphilic bilayer permeability and solvent layer in a random aggregates induced by the liquid crystal phase to the isotropic phase transition. PEG longer the molecular chain, the higher the efficiency of induced phase transition. In addition, the single-phase region of TX-100/n-C8H17OH/PEG (aq) system, PEG Liquid Crystals there is a critical molecular weight, the molecular weight of the PEG Liquid Crystals. The critical molecular weight regardless of the size and thickness of the solvent layer. For the system TX-100/n-C8H17OH/H2O critical molecular weight of the PEG 2000.5. Nuclear magnetic resonance (NMR), polarized optical microscopy (POM), small-angle X-diffraction (SXRD) and the measurement of the rheological properties of the triblock block copolymers F127, P123 lamellar liquid crystal with TX-100/n-C8H17OH/H2O system interactions. And comparison with the F127 hydrophobic fragment PPG4000, PEG4000 and hydrophilic segment and a hydrophobic fragment mixture of PPG 4000, in order to examine the composition and conformation of the block copolymer chains affect its interaction with a lamellar liquid crystal. The results show that: the block copolymers of hydrophobic and hydrophilic even the role of the lamellar liquid crystal at the same time lead to a lamellar liquid crystal to isotropic phase transition. Driven by hydrophobic forces, F127 PPO segments dissolved amphiphilic bilayer of the lamellar liquid crystal, making the increase of the thickness of the amphiphilic bilayer of surfactant molecules arranged in an orderly drop of water in the amphiphilic bilayer an increase in the permeability. The length of the hydrophilic chain of the block copolymer is induced by the mechanism of the lamellar liquid crystal phase to the isotropic phase transition. The longer the hydrophilic chain in the solvent layer of random aggregates cause the liquid crystal layer is bent, so that the phase transition occurs; geopositioning a shorter hydrophilic connected places cosurfactant form amphiphilic Duplex hydrophilic group, resulting in surface The active agent molecule layer spacing increases, so that the phase transition occurs. In addition, the split of the hydrophobic chain and a hydrophilic chain of the block copolymer contribute to the induction of phase transition.

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Polymer physics and physical chemistry of polymers > The chemical nature of polymers
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