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Equilibrium swelling behavior of crosslinked chitosan hydrogels

Ostrowska-Czubenko J., Pieróg M., Gierszewska-Drużyńska M.

Polish Journal of Applied Chemistry

2011

Vol. 55, nr 2

49-56

Chemically and physically crosslinked chitosan hydrogels were obtained by treating chitosan (Ch) with glutaraldehyde (GA) and sodium tripolyphosphate or GA and sodium citrate, GA and sulfuric acid and GA and sulfosuccinic acid, respectively. The formation of covalent and ionic crosslinks between Ch, GA and low molecular ionic compounds was confirmed by FTIR spectroscopy. There was examined the equilibrium degree of swelling of membranes formed from uncrosslinked and crosslinked chitosan hydrogels in buffer solutions of different pH. It was observed that the swelling of all studied membranes was highly dependent on pH.

Efect of ionic crosslinking on chitosan membrane swelling in extracellular hanks' buffer

Gierszewska-Drużyńska M., Ostrowska-Czubenko J.

Polish Journal of Applied Chemistry

2011

Vol. 55, nr 1

1-9

Two- and three-component chitosan membranes (Ch) crosslinked with sodium tripolyphosphate (TPP) and/or sodium alginate (NaAlg) were prepared. Formation of ionic crosslinks between Ch and high-molecular compound - NaAlg and/or low-molecular - TPP was confirmed by FTIR spectroscopy. The effcct of crosslinking agents on membrane swelling in extracellular Hanks' buffer was estimated. The obtained results allow to state, that ionic crosslinking of chitosan results in increase of membrane stability in extracellular media. However, only TPP crosslinkcd chitosan membranes are not soluble in Hanks' buffer.

Ceramic precursors prepared from linear polysiloxanes

Nyczyk A., Klimek A., Wójcik M., Hasik M., Pośpiech P., Cypryk M.

Polish Journal of Applied Chemistry

2011

Vol. 55, nr 2

57-63

Preceramic polysiloxanes have been obtained by cross-linking of linear vinylmethylsiloxane copolymers of regular chain microstructure with linear and cyclic hydrogensiloxanes. It has been found that the efficiency of cross- linking process (studied by IR spectroscopy) and the yields of the ceramic materials obtained after pyrolysis of cross-linked polymers (determined by TG analysis) depend on the chain microstructure of the polymer subjected to cross-linking as well as on the type of cross-linking agent applied.

In situ generated lewis acids in crosslinking of styrene-butadiene rubber

Bociong K., Rzymski W. M.

Polish Journal of Applied Chemistry

2009

Vol. 53, nr 3

209-214

New unconventional method of crosslinking of styrene-butadicnc rubber (SBR) and chlorobutyl rubber (CIIR) was investigated. SBR crosslinking was initiated by Lewis acids generated in situ. The blends of SBR'CIIR/ZnO were heated at temperature of 433 K. for 25 minutes and after that selected properties of the curcd products were determined. It was found that degree of crosslinking increases with increasing amount of CIIR in the blends, but docs not depend on ZnO for ZnO>3 phr CIIR, where 'phr' means parts per hundred of chlorobutyl rubber. Tensile strength (TSb), elongation at break (Eb) and other properties of curcd blends depend on crosslinking conditions and composition of analyzed blends. On the base on sol-gel analysis and extraction in boiling acetone wc have found that degree of SBR-CIIR intcrclastomcrs bounding in common network increases with CIIR amount in the blends.