Hydrogels are three-dimensional network of polymers, which have the capability to absorb a large amount of water or biological fluids. These materials consist of hydrophilic crosslinked polymer chain, which are able to swell, having a soft rubbery consistency similar to living tissues. For this reason, hydrogels are used for biomedical, biotechnology and pharmaceutical applications1,2. The nature of the used crosslinker divides hydrogels in two large families namely physical or chemical crosslinked. In chemical hydrogel, crosslinking is obtained by covalent bond, either during the polymerization or in a post polymerizzazion process3. Physical hydrogels are obtained using physical interaction such as hydrophobic association, ionic bond or hydrogen bond. In this work we prepared physically crosslinked hydrogels by radical micellar polymerization. This type of polymerization involved the use of a hydrophilic monomer (Acrylamide), a hydrophobic monomer (Octadecylacrylate), a surfactant (Sodium dodecyl sulfate), and a salt (NaCl). The polymerization was initiated using a redox initiator system composed of ammonium persulfate and sodium metabisulfite. In addition, a multifunctional monomer, divinylbenzene, was used with the aim of creating branched chains to evaluate their effect on the characteristics of the materials. Three series of five samples were prepared by varying, within the series, the quantity of Octadecylacrylate (C18A), and, between the series, the quantity of Divinylbenzene (DVB). The samples were characterized with thermal (DSC) and rheological analysis, both before and after the washing phase. As the concentration of C18A increases, the amount of water present at equilibrium within the hydrogels decreases. In addition, the melting and crystallization enthalpies increases and an increase is also seen in mechanical modulus G '. On the other hand, as the DVB concentration increases, the water content decreases and the mechanical modulus increases. This phenomenon is probably caused by the formation of chemical cross-linking points within the polymer network. The self annealing behaviour of these materials was also demonstrated by several rheology measurements.
SYNTHESIS AND CHARACTERIZATION OF SELF HEALING HYDROGELS BY MICELLAR POLYMERIZATION
Podda E.
2020-01-01
Abstract
Hydrogels are three-dimensional network of polymers, which have the capability to absorb a large amount of water or biological fluids. These materials consist of hydrophilic crosslinked polymer chain, which are able to swell, having a soft rubbery consistency similar to living tissues. For this reason, hydrogels are used for biomedical, biotechnology and pharmaceutical applications1,2. The nature of the used crosslinker divides hydrogels in two large families namely physical or chemical crosslinked. In chemical hydrogel, crosslinking is obtained by covalent bond, either during the polymerization or in a post polymerizzazion process3. Physical hydrogels are obtained using physical interaction such as hydrophobic association, ionic bond or hydrogen bond. In this work we prepared physically crosslinked hydrogels by radical micellar polymerization. This type of polymerization involved the use of a hydrophilic monomer (Acrylamide), a hydrophobic monomer (Octadecylacrylate), a surfactant (Sodium dodecyl sulfate), and a salt (NaCl). The polymerization was initiated using a redox initiator system composed of ammonium persulfate and sodium metabisulfite. In addition, a multifunctional monomer, divinylbenzene, was used with the aim of creating branched chains to evaluate their effect on the characteristics of the materials. Three series of five samples were prepared by varying, within the series, the quantity of Octadecylacrylate (C18A), and, between the series, the quantity of Divinylbenzene (DVB). The samples were characterized with thermal (DSC) and rheological analysis, both before and after the washing phase. As the concentration of C18A increases, the amount of water present at equilibrium within the hydrogels decreases. In addition, the melting and crystallization enthalpies increases and an increase is also seen in mechanical modulus G '. On the other hand, as the DVB concentration increases, the water content decreases and the mechanical modulus increases. This phenomenon is probably caused by the formation of chemical cross-linking points within the polymer network. The self annealing behaviour of these materials was also demonstrated by several rheology measurements.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
