Polymers are used in pharmacy as excipients in the drug manufacture. Most often, polymers are used to protect API from moisture, light, specific conditions in the GIT, stabilize suspensions / emulsions, control release of the API… The master's thesis was focused on kappa-carrageenan, it is a natural polymer and is used as an excipient for controlled release of the API and as a binder for soft tableting. Using two different analytical approaches, we evaluated the physicochemical properties of kappa-carrageenan of different types, manufacturers and series.
Using an atomic force microscope, individual polymer chains were prepared from solutions with different polymer concentrations. At lower concentration, individual chains with loops and knots were detected. Some series of kappa-carrageenan formed networks. At higher concentration, networks and individual chains were not observed, only disordered and aggregating structures were noticed.
The mechanical properties of polymer films were determined by instrumental nanoindentation. The Young's modulus and the hardness was measured. The method is non-destructive and requires only a minimal amount of sample, what is especially important in pre-formulation research. A linear correlation between persistence length and Young's modulus and persistence length and hardness were presented.
At the macroscopic level, the Young's modulus is a measure of elasticity. A hardness is a measure of plasticity. Plastic and elastic deformation are very important in the tablet compression process, where a temporary redistribution of particles, elastic deformation, plastic deformation and finally fragmentation are done.
Regarding the wide range of parameter values were determined, it can be concluded that there are large variations between different series of natural polymers. Physicochemical properties also indirectly affect the final properties of the tablets, such as strength, elasticity, swelling and dissolution rate.
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