Confined Crystallization and Melting Behaviors of 3-Pentadecylphenol in Anodic Alumina Oxide Nanopores.

ACS Omega

State Key Laboratory of High-Efficiency Coal Utilization and Green Chemical Engineering, Ningxia University, 489 Helanshan West Road, Yinchuan 750021, China.

Published: July 2021

AI Article Synopsis

  • - The study investigates how end groups affect the crystallization of 3-pentadecylphenol (PDP) when confined within anodic aluminum oxide (AAO) templates, revealing that confinement disrupts the stacking of alkyl chain end groups and alters thermal stability.
  • - Wide-angle X-ray diffraction (WAXD) indicated solid-solid phase transitions in confined PDP, while differential scanning calorimetry (DSC) showed that cooling rates and confinement conditions impact crystallization behavior significantly.
  • - The introduction of phenolic end groups changed the melting characteristics and disappearance of the surface freezing layer in the alkyl chain, making confined PDP more sensitive to adjustments in AAO pore sizes compared to a control sample, C. *

Article Abstract

To explore the effects of end groups on the confined crystallization of an alkyl chain, 3-pentadecylphenol (PDP) was infiltrated into the anodic aluminum oxide template (AAO) to investigate the melting and crystallization behaviors of PDP in a nanoconfined environment. Wide-angle X-ray diffraction (WAXD) found that the solid-solid phase transition of PDP occurred under confined conditions, and the absence of the (00L) reflections indicated that the stacking of the end groups of the alkyl chain layered structure was seriously disturbed. Thermal analysis (TG) showed that the thermal stability of the confined samples decreased due to the confinement effect, and the introduction of end groups made the confinement effect more obvious. Differential scanning calorimeter (DSC) results well reflected the space-time equivalence in the PDP crystallization processes, i.e., the solid-solid phase transition can be achieved by reducing the cooling rate or confining PDP in the nanometer space. Compared with C, the introduction of the end groups with a phenol ring led to the disappearance of the solid-solid phase transition of an alkyl chain at high cooling rates. In the confined environment, the introduction of the end groups with a phenol ring caused the melting double peaks of the alkyl chain to become a single melting peak, and it also caused the disappearance of the surface freezing monolayer for alkyl chains. Through the analysis of crystallinity, it was found that AAO-PDP was more sensitive to AAO pore size changes than AAO-C, the of AAO-PDP had a good linear relationship with the pore size , but the of the AAO-C had a nonlinear relationship with the pore size . Attenuated total reflection (ATR)-IR proved that in the confined environment, the order of the alkyl chain decreased and the degree of chain distortion increased.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8296606PMC
http://dx.doi.org/10.1021/acsomega.1c02112DOI Listing

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