title: The development of thermal nanoprobe methods as a means of characterizing and mapping plasticizer incorporation into ethylcellulose films.
abstract: OBJECTIVE
  The phase composition and distribution of ethylcellulose (EC) films containing varying amounts of the plasticizer fractionated coconut oil (FCO) were studied using a novel combination of thermal and mapping approaches.
  
  
  METHODS
  The thermal and thermomechanical properties of films containing up to 30% FCO were characterized using modulated temperature differential scanning calorimetry (MTDSC) and dynamic mechanical analysis (DMA). Film surfaces were mapped using atomic force microscopy (AFM; topographic and pulsed force modes) and the composition of specific regions identified using nanothermal probes.
  
  
  RESULTS
  Clear evidence of distinct conjugate phases was obtained for the 20-30% FCO/EC film systems. We suggest a model whereby the composition of the distinct phases may be estimated via consideration of the glass transition temperatures observed using DSC and DMA. By combining pulsed force AFM and nano-thermal analysis we demonstrate that it is possible to map the two separated phases. In particular, the use of thermal probes allowed identification of the distinct regions via localized thermomechanical analysis, whereby nanoscale probe penetration is measured as a function of temperature.
  
  
  CONCLUSIONS
  The study has indicated that by using thermal and imaging techniques in conjunction it is possible to both identify and map distinct regions in binary films.
authors.affiliation: School of Pharmacy, University of East Anglia, Norwich, UK.
authors.forename: Jin
authors.initials: J
authors.lastname: Meng
authors.forename: Marina
authors.initials: M
authors.lastname: Levina
authors.forename: Ali R
authors.initials: AR
authors.lastname: Rajabi-Siahboomi
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Round
authors.forename: Mike
authors.initials: M
authors.lastname: Reading
authors.forename: Duncan Q M
authors.initials: DQ
authors.lastname: Craig
mesh_terms: D002152:Calorimetry, Differential Scanning; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D003059:Cocos / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D044367:Phase Transition; D010938:Plant Oils / Q000032:analysis*; D010968:Plasticizers / Q000032:analysis*; D013696:Temperature
chemical_list: D010938:Plant Oils; D010968:Plasticizers; C013517:ethyl cellulose; D002482:Cellulose