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Synthesis and Properties of Polyesters Based on Coffeic Acid

Author: LiHuiLing
Tutor: XieYi；ChenMingQing
School: Jiangnan University
Course: Materials Science
Keywords: 3,4 - dihydroxy - cinnamic acid Lithocholic Polyethylene glycol Biodegradable polyester Micelle
CLC: O633.5
Type: Master's thesis
Year: 2011
Downloads: 21
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Abstract


3,4 - dihydroxy - cinnamic acid (DHCA) and lithocholic acid (LCA) as monomers, P (DHCA-co-LCA) is prepared by melt polycondensation biodegradable polyester. Proton nuclear magnetic resonance spectroscopy (1H-NMR), Fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC) to characterize the molecular structure and molecular weight of the P (DHCA-co-LCA), the results show that the poly The ester is a clear structure, and the molecular weight can be controlled within the range of 1.59 × 104 ~ 2.15 × 104 of. Using differential scanning calorimetry thermal (DSC), thermogravimetric (TGA), fluorescence spectroscopy, and ultraviolet spectroscopy (UV), respectively P (DHCA-co-LCA) a glass transition temperature (Tg), thermal stability and a photosensitivity study : no significant change as LCA content increases, the Tg of the polyester, but its thermal stability is gradually increased; When the LCA feeding amount of 10wt%, the resulting polyester solution at excitation wavelength of 402 nm having the strongest fluorescence emission strength; solution of the polyester hanging coated film-forming, the characteristic absorption peak at a wavelength of 326nm, and its absorption intensity gradually weakened the increase of UV irradiation (λ gt; 310nm) time, show that the cross-linking reaction gradually; on polyester plate accelerated degradation test showed that the introduction of LCA can regulate the degradation rate of polyesters. Changing the amount of water added, so that P (DHCA-co-LCA) in N, N-dimethyl formamide / water mixed medium of self-assembled to form a stable micelles, using laser light scattering (LLS), and transmission electron microscopy ( TEM) to characterize the resulting micelles. The results indicate that the micelle surface is smooth, uniform particle size, number average particle diameter of the micelle is gradually reduced as the DHCA unit number; with UV irradiation is gradually increased with increasing the concentration of micelle average particle diameter of the polyester solution; (λ GT; 310nm) time is increased, gradually increases the degree of light crosslinking polyester micelle, the particle size variation before and after the crosslinking by the PDL3-7 (DHCA: LCA molar ratio of 3:7) to to PDL9-1 (DHCA: LCA molar ratio of 9:1) successively decreases. P (DHCA-co-LCA) micelle degradation in alkaline buffer solution in four days, eight days after the morphology and size changes, the micelle has a good performance of the degradation. Explore P (DHCA-co-LCA) synthesis and properties of the basis for the change of the flexibility of the polyester molecules, the introduction of a certain molecular weight polyethylene glycol (PEG), by melt polycondensation method successfully prepared ternary -b-PEG block P (DHCA-co-LCA), polyester, and a molecular weight of about 2.0 × 104; found with increasing PEG feeding amount, the Tg of the polyester gradually reduced, and the fluorescence emission intensity gradually decreased; UV measurement results show that the polyesters have certain characteristics in λ light reversible GT; 310nm and λ = 254nm UV irradiation, respectively, the crosslinking reaction of the crosslinkable reconciliation occurs. Changing the amount of water added, so that P (DHCA-co-LCA)-b-PEG self-assembled to form stable micelles in N, N-dimethyl formamide / water mixed medium, TEM observation showed that the micelle smooth surface of the spherical structure, the average particle diameter of about 378nm; showed an increasing trend with the the polyester solution concentration increases the decrease and the increase of water content, PEG content, the particle size of the micelles. Micelle degradation in alkaline buffer solution according to the P (DHCA-co-LCA)-b-PEG 2 days, 4 days after the morphology and the particle size variation, indicating that the introduction of the PEG, to accelerate the degradation of the polyester micelles, its degradation speed is greater than P (DHCA-co-LCA) micelle.

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CLC: > Mathematical sciences and chemical > Chemistry > Polymer chemistry ( polymer ) > Miscellaneous Chain Polymers > Heterocyclic polymer chain (chain polymer containing heterocyclic )
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