Study On The Preparation Of Stimuli-Responsive Microgrl With Core-Shell Structure

Microgel refers to the three-dimensional crosslinked structure of the polymer with a size of a few microns, which swells but cannot be dissolved in solvent and could fast response to environmental stimuli. Thus, the microgel has received widespread attention in the biomedical field. Compared with the traditional methods of preparing microgel, the methods based on supramolecular or synergistic effect is more convenient and faster. Due to the presence of non-covalent bonds, the physical and chemical properties of supramolecular microgel are dynamically reversible. In this paper, the method of build a core-shell microgel structure bsaed on double supramolecular effect (charge attraction/ host-guest, the electron accepter-donor/hydrophilic-hydrophobic) has been researched. The main contents and results are as follows:(1) The linear long-chain molecules mPEG modified by P-CD were synthesized successfully though multi-step reaction and characterized by Fourier transform infrared spectroscopy and 1H NMR characterization.(2) The self-assembly microgel of mPEG-CD, POSS and 2,6-naphthalenedisulfonates in aqueous solution has been prepared through the charge attraction effect and the host-guest assemble. The UV-visible spectroscopy and 2D 1H NOESY spectroscopy confirmed the occurrence of host-guest assemble. The particle size range assembly of 250-400nm has been observed by dynamic light scattering and transmission electron microscopy, and confirmed the core-shell structure. It could been speculated that the inside of microgel are the POSS aggregates formed by charge attraction and the outside of microgel are the long-chain molecules mPEG-CD connected by host-guest effect with 2,6-naphthalenedisulfonates. After adding NaCl or amantadine hydrochloride solution, the core-shell structure can no longer be observed. It confirmed the original supramolecular system has been destructed.(3) Three different aromatic Schiff base have been prepared by condensation reaction between aromatic aldehyde and benzidine. The dendrimers PAMAM3.0 were modified by naphthalene groups to obtain PAMAM-N and the hydroxyl of linear macromolecules mPEG substituted by anthracene to obtain mPEG-A, respectively. They chemical structure were confirmed by FTIR and 1H NMR.(4) The schiff base S2, PAMAM-N, mPEG-A mixed and self-assemble in aqueous solution. The UV-Vis and fluorescence spectroscopy confirmed the formation of supramolecular assembly. The microgel was found the core-shell structure by the characterization of transmission electron microscopy. It could been speculated that the inside of microgel are the PAMAM-N aggregates formed by electron accepter-donor effect between PAMAM-N and shift base and the outside of microgel are the long-chain molecules mPEG-A connected by hydrophilic-hydrophobic effect.