Polyoxyethylene Cholesterol Ether Containing Liquid Crystalline Cell In The Body In The Self-assembly Behavior

Self-assembly of polymers is a powerful tool for producing regularly functional materials that combine several properties. It has received substantial attention during the past few years.In this paper, self-assembly of a series of poly(oxyethylene) (PEO) cholesterol ethers (CS-EOn, n=5, 10, 15, 20, 24, 30, and 45) which contain both liquid crystalline (LC) and crystalline moiety (PEO), was studied by differential scanning calorimetry, wide angle X-ray diffraction, Raman spectrometry, small angle X-ray scattering and polarized light microscope. SAXS results show that lamellar structure was formed in all CS-EOn.In CS-EO5, in which the weight of PEO is low, PEO is amorphous and LC is found to be dominated in determining morphology of CS-EO5 that is composed of double layers of cholesterol and single layer of amorphous PEO. In CS-EO10 and CS-EO15, in which crystallinity of PEO increases slightly, the helical and amorphous conformations of PEO co-exist and LC and crystalline phase co-exist as well. Because of the interplay of LC and crystalline moieties, polymorphism is observed in CS-EO10 and CS-EO15. With the increasing of the chain length of PEO, the crystallinity of PEO increases rapidly and the crystalline PEO becomes dominant in determining the morphology. The increase of PEO crystallinity induces LC moieties to pack more closely and the two layers merge into one single layer gradually.Isothermal crystallization of CS-EO10 and CS-EO15 shows that pre-existing LC moieties increase can nudeate and accelerate crystallization of PEO, but growth dimension of PEO crystals is reduced.In CS-PEG2000 where PEG crystalline is confined in some directions and exhibits irregular spherical and leaf-like crystals because of the effect of cholesterol group-end, and PEG in CS-PEG2000-CS exhibits only needle-like crystals. Cholesterol retards the PEG crystalline rate and decreases the crystallinity of PEG.