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Smart hydrogels which reversibly respond to the change in their environment have many applications in drug delivery,analytical separation and soft mechanics.Temperature and pH sensitive hydrogels are most comprehensively studied because these parameters change naturally and can be easily controlled.Poly(N-isopropylacrylamide)(PNIPAM)and poly(N,N-diethylacrylamide)(PDEAM)are well-known thermoresponsive polymer.However deprived mechanical,thermoresponsive and biocompatible properties of native thermoresponsive hydrogels are the bottlenecks in its practical application.Combining the thermoresponsive polymer with another polymer in interpenetration polymer network(IPN)can greatly enhance these properties.In this work,KGM and polyvinyl alcohol(PVA)combined hydrogel(KGM-PVA)of high mechanical strength as one network of SIPN hydrogel was prepared by the acetylation of the KGM and use of strong alkali(potassium hydroxide-KOH)as gelation inducing agent.KGM was acetylated by using pyridine as catalyst and acetic anhydride as acetyl group donor.This acetylation was performed to increase the solubility of KGM and delay its gelation.Increase in stretching vibration of free C=O group at1727cm-1in FTIR was used as an indication of the successful incorporation of acetyl group.Catalysts dependent degree of acetylation was observed.Degree of acetylation of KGM and strength of KOH was optimized for maximum mechanical strength.Using this procedure,the KGM-PVA hydrogel of high compressive strength(up to4MPa)was obtained.Thermoresponsive property was successfully added into the resulting KGM-PVA hydrogel using PNIPAM and PDEAM as thermoresponsive component.Both polymers(PNIPAM and PDEAM)enhanced the modulus of the hydrogel. Hydrogels of very high modulus were achieved(up to800KPa with PNIPAM and1200KPa with PDEAM).Incorporation of thermoresponsive polymer at low concentration(＜=1.5M)decreased the compressive and tensile modulus due to low strain at break.Incorporation of PNIPAM or PDEAM to the KGM-PVA network greatly enhanced the de-swelling rate.Native thermoresponsive hydrogels did not drop its50％water even in2h,while all the SIPN hydrogels lost50％water in less than20minutes.First order kinetics was successfully applied to the de-swelling of the hydrogels.High concentration of KGM increased the de-swelling rate while elevated level of thermoresponsive polymer decreased it.Increasing the freeze thawing cycle increased the de-swelling rate.Lower critical solution temperature(LCST)of PNIPAM containing hydrogel increased with increase in KGM concentration and reached up to37℃,which is very close to human body.PNIPAM was found to intertwine the KGM-PVA hydrogel at molecular level as revealed by DSC,XRD and FTIR.With high molar PDEAM,compressive strength up to12MPa and tensile strength up to7MPa was achieved.PDEAM based hydrogels exhibited slightly lower de-swelling rate than PNIPAM based hydrogel. The prepared hydrogel was also used as ethanol responsive membrane.In the hydrogel network,KGM-PVA provides the necessary structural strength and PNIPAM allows ethanol dependent flux.Under a certain conditions of temperature and ethanol concentration the PNIPAM swells inside the KGM network,thus impede the permeation.When the conditions are altered the PNIPAM is shrunken and the pore size of the hydrogel is increased and consequently the flow of the water/ethanol mixture is also increased.In other words the gates of the hydrogel membrane are either"closed"or"open"depending on the temperature and ethanol concentration.The addition of co-monomers;acrylamide,acrylic acid and N,N-diethylacrylamide can alter the closed/open position based on the concentration of ethanol.