Solid-liquid equilibrium and heat capacity trend in the alkylimidazolium PF6 series

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22340%2F17%3A43914614" target="_blank" >RIV/60461373:22340/17:43914614 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0167732217300582" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0167732217300582</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.molliq.2017.10.042" target="_blank" >10.1016/j.molliq.2017.10.042</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Solid-liquid equilibrium and heat capacity trend in the alkylimidazolium PF6 series

Popis výsledku v původním jazyce

The heat capacity and thermal behavior trend along the 1-alkyl-3-methylimidazolium hexafluorophosphate [CnC1im][PF6] (with n = 2?10, 12) ionic liquids series, is used to explore the effect of the alkyl chain length in the nanostructuration. The heat capacities of the studied ILs were measured with an uncertainty better than ?0.15% and are in excellent agreement with the available data in the literature. An odd-even effect for the specific and volumic heat capacities of the [CnC1im][PF6] series was found. The observed odd-even effect in the liquid heat capacity was rationalized considering the preferential orientation of the terminal -CH3 group. The higher specific/volumic heat capacities shown for the [C6C1im][PF6] and [C8C1im][PF6] are an indication of an additional conformational disorder increase in the liquid phase that could be related with a weaker alkyl chain interdigitation capability of the even number chain ILs. The melting temperature and consequent enthalpy and and entropy of fusion trend along the alkyl series present a V-shape profile that is explained based on the analysis of the balance between the initial decrease of the electrostatic interaction potential and the increase of the van der Waals interactions with the increasing size of the alkyl side chain of the cation. The inhibition of crystallization for intermediate alkyl chain size (from [C5C1im][PF6] to [C8C1im][PF6]) seems to arise from the overlapping of the hypothetical cold crystallization temperature by the melting temperature. Above the critical alkyl size, CAS, a regular increase in the entropy and enthalpy profiles presents a similar shape than the observed in other alkane series and is a strong support of the intensification of the ILs nanostructuration.

Název v anglickém jazyce

Solid-liquid equilibrium and heat capacity trend in the alkylimidazolium PF6 series

Popis výsledku anglicky

The heat capacity and thermal behavior trend along the 1-alkyl-3-methylimidazolium hexafluorophosphate [CnC1im][PF6] (with n = 2?10, 12) ionic liquids series, is used to explore the effect of the alkyl chain length in the nanostructuration. The heat capacities of the studied ILs were measured with an uncertainty better than ?0.15% and are in excellent agreement with the available data in the literature. An odd-even effect for the specific and volumic heat capacities of the [CnC1im][PF6] series was found. The observed odd-even effect in the liquid heat capacity was rationalized considering the preferential orientation of the terminal -CH3 group. The higher specific/volumic heat capacities shown for the [C6C1im][PF6] and [C8C1im][PF6] are an indication of an additional conformational disorder increase in the liquid phase that could be related with a weaker alkyl chain interdigitation capability of the even number chain ILs. The melting temperature and consequent enthalpy and and entropy of fusion trend along the alkyl series present a V-shape profile that is explained based on the analysis of the balance between the initial decrease of the electrostatic interaction potential and the increase of the van der Waals interactions with the increasing size of the alkyl side chain of the cation. The inhibition of crystallization for intermediate alkyl chain size (from [C5C1im][PF6] to [C8C1im][PF6]) seems to arise from the overlapping of the hypothetical cold crystallization temperature by the melting temperature. Above the critical alkyl size, CAS, a regular increase in the entropy and enthalpy profiles presents a similar shape than the observed in other alkane series and is a strong support of the intensification of the ILs nanostructuration.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Molecular Liquids

ISSN

0167-7322

e-ISSN

—

Svazek periodika

248

Číslo periodika v rámci svazku

14. říjen 2017

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

10

Strana od-do

"678?687"

Kód UT WoS článku

000418314400082

EID výsledku v databázi Scopus

2-s2.0-85032347291