PURPOSE: The effects of milling and particle size on surface energies of form I paracetamol crystals are reported. METHODS: Paracetamol crystals (75-850 microm) were obtained by cooling methanol and acetone saturated solutions. Additionally, macroscopic (>2 cm) single crystals were grown by slow solvent evaporation from saturated solutions, ball milled and sieved into different particle size fractions. Surface properties were characterised using Inverse Gas Chromatography and compared with those calculated from sessile drop contact angle measurements on macroscopic single crystals. RESULTS: Dispersive surface energies, gamma(d)SV for milled samples increased by 20% with decreasing particle size. With decreasing particle size acceptor numbers, KA values were constant but donor numbers, KB decreased. For unmilled materials KB was comparable to KA but with a significantly lower gamma(d)SV of only 33 mJ/m(2). Milling resulted in fracture along the crystal's lowest attachment energy plane (010), exposing facets of different surface chemistry to that of the native external facets theta for the (010) fracture plane confirmed a higher gamma(d)SV compared to external facets such as (011) of single crystals. CONCLUSIONS: Milling exposes a hydrophobic surface for paracetamol form I crystals which becomes increasingly more dominant with decreasing particle size.
PURPOSE: The effects of milling and particle size on surface energies of form I paracetamol crystals are reported. METHODS:Paracetamol crystals (75-850 microm) were obtained by cooling methanol and acetone saturated solutions. Additionally, macroscopic (>2 cm) single crystals were grown by slow solvent evaporation from saturated solutions, ball milled and sieved into different particle size fractions. Surface properties were characterised using Inverse Gas Chromatography and compared with those calculated from sessile drop contact angle measurements on macroscopic single crystals. RESULTS: Dispersive surface energies, gamma(d)SV for milled samples increased by 20% with decreasing particle size. With decreasing particle size acceptor numbers, KA values were constant but donor numbers, KB decreased. For unmilled materials KB was comparable to KA but with a significantly lower gamma(d)SV of only 33 mJ/m(2). Milling resulted in fracture along the crystal's lowest attachment energy plane (010), exposing facets of different surface chemistry to that of the native external facets theta for the (010) fracture plane confirmed a higher gamma(d)SV compared to external facets such as (011) of single crystals. CONCLUSIONS: Milling exposes a hydrophobic surface for paracetamol form I crystals which becomes increasingly more dominant with decreasing particle size.
Authors: Raimundo Ho; Majid Naderi; Jerry Y Y Heng; Daryl R Williams; Frank Thielmann; Peter Bouza; Adam R Keith; Greg Thiele; Daniel J Burnett Journal: Pharm Res Date: 2012-08-08 Impact factor: 4.200
Authors: Umang V Shah; Dolapo Olusanmi; Ajit S Narang; Munir A Hussain; Michael J Tobyn; Steve J Hinder; Jerry Y Y Heng Journal: Pharm Res Date: 2014-07-19 Impact factor: 4.200
Authors: Eftychios Hadjittofis; Mark Antonin Isbell; Vikram Karde; Sophia Varghese; Chinmay Ghoroi; Jerry Y Y Heng Journal: Pharm Res Date: 2018-03-19 Impact factor: 4.200