Phase behaviour of transkarbam 12.

Area of Science:

• Materials Science
• Physical Chemistry
• Biophysics

Background:

• Transkarbam 12 (T12), a carbamic acid salt of omega-aminocaproic acid dodecyl ester, demonstrates significant potential as a permeation enhancer for transdermal drug delivery.
• Understanding the thermotropic phase behavior of T12 is crucial for optimizing its formulation and application in drug delivery systems.

Purpose of the Study:

• To investigate the thermotropic phase behavior of Transkarbam 12 (T12) using multiple analytical techniques.
• To elucidate the structural and chemical changes occurring in T12 during heating and cooling cycles.

Main Methods:

• Differential Scanning Calorimetry (DSC) for thermal transitions.
• Fourier Transform Infrared (FTIR) and FT-Raman spectroscopy for structural and conformational analysis.
• X-ray powder diffraction (XRD) for structural ordering.
• UV-Vis Diffuse Reflectance Spectroscopy (DRS) for electronic properties.

Main Results:

• At room temperature, T12 exhibits an ordered orthorhombic perpendicular subcell structure in its hydrocarbon chains.
• Two distinct thermal transitions were observed at 54°C and 66°C.
• The transition at 54°C involves carbamate structure disruption and polar head group changes, while the 66°C transition signifies hydrocarbon chain melting and CO2 release.

Conclusions:

• T12 undergoes significant structural rearrangements upon heating, impacting its chemical integrity and physical state.
• The observed phase transitions, including CO2 release, provide insights into the stability and potential degradation pathways of T12.
• Further studies are needed to precisely determine the kinetics of CO2 rebinding and carbamate reformation, critical for its application.