Kink Block Structures in Clay Organic Complexes

Complexes of n-tetradecylammonium-beidellite with n-alkanols ${(n - }{{C}_{{14}}}{{H}_{{29}}}{N}{{H}₃}⁺{{)_{{0,44}}(n - C_{{x}}}}{{H}_{{2x}}}{+}{}₁{OH) }{}_{{1,56}}{{{\{ M}}{{g}_{{0,28}}}{A}{{l}_{{1,81}}}{{(OH)}₂}{S}{{i}_{{3,56}}}{Al}{}_{{0,44}}{{O_{{10\}} }}}^{{0,44 - }}}$ (x = 8–22) have been prepared and characterized by their basal spacings and by measurements of the specific heat cp. The compounds undergo a series of reversible phase transitions ${β _1} ...{β_i}...{β_ω}{α_1}...{α_j}$ with rising temperature. The maximum number ω of β-phases depends upon the chain lengths and increases from 1 with decanol to 6 with docosanol. Due to the evaporation of alkanol the number of χ-phases is not yet established in all details. The β-transitions correspond to conformational changes of the alkyl chains via rotational isomerisation, especially kink formation. The β-phases become unstable if the kink concentration exceeds 0,14 kinks/-CH2-. The β/α-transition is probably caused by a rearrangement into special gauche-block structures.