Ethylene oxide spacers

Fig. 14 (a) Chemical structures of the polyphilic dispersion-promoter molecules, (b) Tailor-designed polyphilic molecules promoting CNT dispersion in the nematic host. Pyrene anchoring group (blue), mesogenic CB unit (dark red), flexible hydrocarbon or ethylene oxide spacer (green), and liquid crystal host (light red) [464]. (Reproduced by permission of The Royal Society of Chemistry)... 

Polymers with poly(ethylene oxide) spacers were shown to have transition temperatures similar to those for polymers with polymethylene spacers of the same length, but the mesophases formed could be quite different, which again emphasizes the importance of the spacer in determining mesophase morphology. Furthermore, polymers with polysiloxane spacers and mesogenic units, identical to those present in polymers with polymethylene spacers having a comparable number of bonds, showed different mesophase structures in addition to much lower transition temperatures. 

Other polymers with oligo ethylene oxide) spacers have been observed. The polymers of limura and coworkers, with mesogenic structures 10 and 12 of Table 1 and spacers of di-, tri- and tetraethylene oxide, had X-ray patterns in the melt that were virtually identical to those of the solid This result was also observed for Polymer 37 with a tetraethylene oxide spacer prepared by us Such patterns are consistent with a smectic E mesophase which maintains much of the solid state order in the liquid crystalline melt. 

He et al. [68] examined the effect of adding flexibility to the hydrogen bond acceptor bis-pyridyl units. They attached stilbazole derivatives to either end of differently sized oligo(ethylene oxide) spacers (4) (Fig. 7). Mixing... 

Fig. 29. Scheme of alternative layer structures of the PEIs v and w A and B antiparallel orientation of the dipoles in the mesogen layers and mixing of alkane and ethylene oxide spacers C and D parallel array of the mesogens and separate layers of alkanes and ethylene oxide... 

The bichromophoric molecule DXA consisting of two coumarins linked by a penta(ethylene oxide) spacer can bind Pb2+ ions in acetonitrile and in propylene carbonate. 

FIG. 8 Dependence of the CMC on the spacer carbon number for the surfactant series 10-5-10 ( , from Ref. 36), 12-5-12 (V, from Ref. 1), and 16-5-16 (O, from Ref. 1 , from Ref. 108). The symbols (A, from Ref. 113) show the results for the surfactants 12-CH2CH2(OCH2CH2)x-12 with a poly(ethylene oxide) spacer. t is the total number of oxygen and carbon atoms in this spacer. 

Figure 1. Some examples of dimeric liquid crystals. Symmetric dimers (a) BCBOn series [19], (b) m.OnO.m series [20], and (c) Discotic dimer [8]. Dimers containing (d) a siloxane-based spacer [15] and (e) an oligo-(ethylene oxide) spacer [14], Non-symmetric dimers (f) CBOnO.m series [27] and (g) K15 [44], Chiral dimers dimers containing a chiral center in (h) the spacer [48] and the terminal chains (i) (S)2MB.OnO.(5)2MB series and (j) CBOnO.(S)2MB series [33].

---