V.—THE LATER MIDDLE AGES, 1200‐c. 1530

Self‐organized liquid‐crystalline polyethers obtained by grafting tapered mesogenic groups onto poly(epichlorohydrin): Toward biomimetic ion channels

“…The chemical modification of PECH under phase-transfer catalyst conditions with carboxylates has been used by several researchers, 26,27 but very few studies have focused on obtaining anisotropic materials. 28,29 The fact that the modification degrees in our previous article were good and that no dehydrochlorination 30,31 side reactions were detected encouraged us to use the same strategy and reaction conditions here.…”

“…The degree of modification obtained in this study was about 10% lower than the one obtained in the modification with potassium 3,4,5-tris(n-dodecan-1yloxy)benzoate, 20 but it can still be considered noticeably high since the molecular weight of the starting PECH is high and the tapered nucleophile is bulky. The literature on modifying PECH of a similar molecular weight with different potassium carboxylates reports 28,35 maximum modification values of around 65%. The existence of this plateau seems to be related to a progressive compaction of the conformational coil as the chlorine displacement progresses, leading to a decrease in the percentage of accessible reactive sites.…”

Synthesis of New Reactive Polyethers: Poly(-bromoalkyl-1-glycidylether)s

“…The components for the Price catalyst (i-PrO) 3 Al/ZnCl 2 (1 : 0.5) were prepared and purified following a procedure reported by us. [22] The catalyst was prepared as a solution 0.10 m in aluminium isopropoxide and 0.05 m in zinc chloride in anhydrous digliet.…”

“…[1] These materials can be molecularly designed by modifying polyethers with halogenated side groups. [2][3][4][5][6][7][8] We have already modified poly-(epichlorohydrin) (PECH) to a large extent with several nucleophiles, but in most cases there were undesirable side reactions such as crosslinking and chain cleavage. [9 -12] This degradative chain scission arises because vinylether moieties form due to dehydrochlorination.…”

“…Region between 81 and 71 ppm of the 13 C NMR spectrum of poly(10-bromo-1,2-epoxydecane) recorded in CDCl 3 including an expansion of the region between 79 and 77 ppm of the spectrum recorded in TCE-d 2 .…”