Zhejiang Univ, Dept Polymer Sci & Engn, Key Lab Macromol Synth & Functionalizat, Hangzhou 310027, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing Synchrotron Radiat Lab, Beijing 100039, Peoples R China
; Pohang Univ Sci & Technol, Dept Chem Engn, Natl Creat Res Ctr Block Copolymer Self Assembly, Pohang 790784, Kyungbuk, South Korea
; Pohang Univ Sci & Technol, Inst Polymer, Div Elect & Comp Engn, Pohang 790784, Kyungbuk, South Korea
Self-assembly of a series of poly(oxyethylene) (POE) cholesterol ethers (ChEOn, n = 5, 10, 15, 20, 24, 30, and 45) bearing both liquid crystalline (LC) and crystalline moieties was studied by differential scanning calorimetry, wide-angle X-ray diffraction, Raman spectrometry, and small-angle X-ray scattering. In ChEO5 where POE is amorphous, the LC moiety was found to be dominant in determining morphology, and the repeating lamellar structure of ChEO5 is composed of double layers of cholesterol and a single layer of amorphous POE. In ChEO 10 and ChEO 15, LC and crystalline phases coexist and polymorphism is observed. The repeating lamellar structures of ChEO10 and ChEO15 are similar to that of ChEO5, except for the crystalline helical conformation of POE. With further increase in the chain length of POE, the crystalline POE becomes dominant in determining morphology, and the LC phase is not detected. The crystalline conformation of POE induces LC moieties to pack more closely, and the two LC layers gradually merge into a single LC layer in the repeating lamellar structure. Nonisothermal and isothermal crystallization experiments show that the preexisting LC phase can nucleate and accelerate POE crystallization, whereas the dimension of crystal growth of POE is reduced.