In-situ analysis of polymer film coats using AFM and thermal probe methods

Baker, David Adam (2012) In-situ analysis of polymer film coats using AFM and thermal probe methods. Doctoral thesis, University of East Anglia.

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The in-situ analysis of pharmaceutical solid dosage forms films is of great interest to pharmaceutical research, especially with the drive towards continuous processing compared to batch processing requiring either in-line or on-line analysis of pharmaceuticals. The size and shape of many solid dosage forms impedes their in-situ analysis, particularly when using thermal analysis techniques such as differential scanning calorimetry (DSC). Thermal probe methods, which combine atomic force microscopy (AFM) with thermal analysis, permits imaging and characterisation of solid dosage forms in-situ. The goal of this thesis is to perform the in-situ analysis of film coated minitablets through the use of thermal probe methods.
Minitablets, which are small diameter tablets, were coated with Opadry I, Opadry II or Surelease, and blends of Surelease and Opadry I and Surelease and Opadry II. In addition the same systems were prepared as cast free films to ascertain differences resulting from the two methods of producing the films. Distinct morphologies were observed between the film coated minitablets and cast free films, particularly for the polymer blends. Thermal analysis by modulated temperature DSC (MTDSC) and localised thermomechanical analysis (L-TMA) of film coated minitablets coated with polymer blends indicating miscibility. However the novel technique of heated tip tapping mode was employed, which was able to resolve separate domains of the polymer blends, which appeared as nanophases. Heated tip tapping mode was further employed to determine changes in the surface morphology of film coated minitablets which had undergone curing. It was successfully used to observe the further coalescence of Surelease and the alteration in the phase distribution of the polymer blends after film coated minitablets had been cured. Polymer films with incorporated pigments were also analysed by thermal probe methods with differences in pigment distribution being observed between film coated minitablets and cast free films. Tapping mode AFM was able to determine the location of pigment particles and the novel use of L-TMA performed in tapping mode allowed thermal analysis without changing AFM mode. Overall the use of AFM combined with thermal probes achieved the aim of performing in-situ analysis of polymer film coats; however further research to correlate in-vivo behaviour of film coats would be of value.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Pharmacy
Depositing User: Users 2593 not found.
Date Deposited: 18 Sep 2013 11:42
Last Modified: 18 Sep 2013 11:42


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