Therefore calculating the MW via a formula can be helpful.Ī commonly used calculation is the Mark-Houwink equation, also known as Mark-Houwink-Sakurada (MHS) equation, where viscosity may be known. With all this, it’s important that MW is calculated and known to effectively and efficiently construct ones chitosan-based system. Generally, the intrinsic viscosity is measured under non-theta conditions so an empirical equation is used to describe the intrinsic viscosity/molecular weight relationship. In the case of chitosan-based hydrogels for example, MW impacts on the form and strength of the hydrogel and release rates of drug delivery systems. The intrinsic viscosity is obtained in the limit of c 2 >0 as h (h - h 0)/(c 2 h 0). It can affect many properties of the material including but not limited to conformation, solubility, viscosity and cytotoxicity ). Molecular weight (MW) of chitosan is the mass of one mole of a substance and influences the physiochemical and rheology of the native chitosan and the materials produced with said chitosan. But this is a Quick Guide to determine MW of chitosan using the Mark-Houwink equation, where viscosity is known. There are several methods to determine the Mw of chitosan. (4) : where K and are empirically determined constants for a given polymer solvent temperature system. proportionality constant of the Mark-Houwink equation k 0.28xlo24 or 0.29xlo24 in Eq. Therefore determining and tuning chitosans’ MW can be critical in meetings a system’s target(s) in its application. The intrinsic viscosity, as function of average molecular weight, M is represented by Mark- Houwink Sakurada equation (in Eq-4). intrinsic viscosity measurement could be replaced by inherent. Shown below are the IV ranges for the main applications: Fibers. Intrinsic viscosity is a measure of the capacity of a molecule of polymer to increase the viscosity of a solvent in the absence of intermolecular interactions. It is found by extrapolating the relative viscosity (measured in (d/g)) to zero concentration. The preferred method is intrinsic viscosity (IV). Chitosans’ MW, degree of deacetylation (DDA), high polydispersity index (PDI), and distribution of acetyl groups are important intrinsic factors of chitosan, which can affect its physicochemical properties, rheology, bioactivity, and interaction with co-materials and tissue. The molecular weight of PET is measured by solution viscosity. Commercial chitosan products are produced with different molecular weight (MW) typically ranging from 100 to 800 kDa.
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