Swelling behavior of strongly anionic hydrogels in polymer solutions

Akrilamid (AAm) ve N-izopropilakrilamid’in (NIPA), farklı oranlarda 2-akrilamido-2-metilpropansulfonik asit sodyum tuzu (AMPS) ile serbest radikal çapraz bağlanma kopolimerizasyonundan anyonik hidrojeller sentezlendi. Jellerin %10’dan 100’e kadar değişen hacim oranlarında poli(etilenglikol)(PEG) içeren sulu çözeltiler içersindeki şişme davranışları incelendi. Deneysel sonuçların teori ile açıklanması  için jellerin su ve saf PEG eriyiği içersindeki şişme oranlarından yararlanarak polimer ağyapı-lineer polimer-çözücüden meydana gelen ve sistemi karakterize eden parametreler hesaplandı ve Flory-Huggins eşitliği yardımıyla sistemin teorik şişme oranları elde edildi. Teorik ve deneysel şişme oranlarının uyum içersinde olduğu görüldü, jellerin PEG çözeltileri içersindeki şişme davranışları açıklandı. Anahtar Kelimeler: Anyonik hidrojeller, Flory-Huggins eşitliği, serbest radikal çapraz bağlanma kopolimerizasyonu, şişme oranları, şişme davranışları.Hydrogels are materials show phase transition by swelling depending on their chemical structure, solvent, pH, temperature, light and electric field etc. In the literature many studies have been published on the swelling behavior of hydrogels in low molecular weight solvents and solvent mixtures. In contrast, a few number of investigations have been reported on the swelling behavior of hydrogels in polymer solutions. In this study of which purpose is determination of swelling behavior of neutral and ionic hydogels in linear polymer solutions, the neutral and ionic poly(acrylamide) (PAAm) and poly(N-isopropylacrylamide) (PNIPA) gels and poly(ethyleneglycole) (PEG) with different molecular weights were preferred as hydrogels and linear polymer, respectively. The effects of ionic group content, PEG concentration of outer aqueous PEG solution and molecular weight of PEG on the swelling behavior of hydrogels in PEG solutions are investigated. In addition of these effects, for PNIPA gels, the temperature effect on the swelling behavior was also researched. On the other hand, the theoretical calculations were performed to these ternary systems (polymer network-linear polymer-solvent) and tried to predict their swelling behavior by using Flory-Rehner theory. Finding from experiments were compared with the theoretical results and the differences between theory and experimental were interpreted. Keywords:  Flory-Rehner theory, hydrogel, swelling behavior