Competition of Crystalline and Liquid Crystalline Moieties in Self-Assembly of Poly(oxyethylene) Cholesterol Ethers

Abstract

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 ChEO10 and ChEO15, 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.

Poly(N-isopropylacrylamide-co-1-vinyl-3-alkylimidazolium bromide) Microgels with Internal Nanophase-Separated Structures

“…The stacking mode of the alkyl chains in the comonomer units can also be inferred from the d spacings. Generally, the alkyl chains can stack into a head-to-head bilayer structure or an interdigitated monolayer structure . The d spacings of the LC mesophases calculated from SAXS and the theoretical lengths for the alkyl chains with an all-trans conformation are listed in Table .…”

A layered liquid crystalline droplet

“…Herein, we describe the self-organization behavior and LC properties of a dumbbell-shaped molecule 1 28 (Scheme 1) containing cholesterol, tetrathiafulvalene (TTF), and 1,5-dioxynaphthalene (DNP) moieties. We introduced cholesterol-a very efficient initiator 23,[29][30][31][32][33][34][35][36][37] of LC formation-into 1 in order to confer self-organizational characteristics and LC properties upon this redox-active compound. The presence of the TTF moiety, in particular, is expected to provide redox control of these LC properties.…”

Synthesis of terpene–poly(ethylene oxide)s by t-BuP4-promoted anionic ring-opening polymerization

“…CholEO57 showed two exothermal peaks in the cooling curve and two corresponding endothermal peaks in the second heating curve (similar to CholEO61), suggesting the coexistence of liquid crystal (LC) and crystalline phases. 54 The transition at lower temperature is due to the crystallization of PEO, T m z 23 C and X c,PEO z 52% (Table 1), while that at higher temperature could be attributed to a liquid-crystalline transition of the cholesteryl entity.…”