| Sensitive hydrogel is polymer cross linking network which has a nature of hydrophilicity and undissolve in water,it can response external environment change(such as pH,ionic strength,temperature,light field,electric field) through its own capacity swelling or contraction,hydrogel has shape with "humidity and soft" after swelling,all these features are the basis of bionic materials design,chemical separation mechanics,drug control release mechanics and chemical valve and so on.In this paper,chemical crosslinking AMPS/DMAEMA and AMPS/DMAEMA/NVP copolymerization intelligent hydrogels are prepared by aqua-solution method, we research temperature-,pH-,ionic strength- and electric field stimulus responsibility of these hydrogels,synthetic process and copolymerization kinetics of AMPS/DMAEMA co-hydrogel have been studied,otherwise some methods of increasing response rate of hydrogel have been researched,the main contents and results are as follows:Bis is used as a cross linker,APS and SBS is used as an oxidation-reduction initiator,hydrogel based on AMPS/DMAEMA has been synthesized in water solution.ESR of hydrogel in pH=0.8 HC1 solution is used as evaluating indicator,the influences of cross linker concentration,initiator concentration,total monomers concentration and mass ratio of reactive monomers on swelling performance of hydrogel are investigated.The result shows that hydrogel with good comprehensive performance can be gained under optimizational experiment conditions,the optimized technological conditions are: cross linker consumption 4.0wt%,initiator consumption 0.5wt%,total monomers concentration 0.2 g/tnL , AMPS: DMAEMA=3:7(mass ratio).The result of IR shows that hydrogels through treated which we used to swelling measurement are polymer network with complete polymerization.The swelling kinetics of AMPS/DMAEMA co-hydrogel and its temperature-,pH-,ionic strength stimulus responsibility have been researched systematically,gel block under experiment specification can reach swelling equilibrium approximately through 4h swelling,the gel present obvious capacity saltation towards different ionic strength or pH,its critical values are 0.1 and 4 individually,but the gel block appear continuouscapacity change nearly under variable temperature under the range of 30 ~ 60C,capacity phase change is unobvious.Hydrogel based on AMPS/DMAEMA/NVP copolymer is a new style intelligent hydrogel,this gel block under experiment specification reach swelling equilibrium by the time greater than 45h,and its swelling is a non-Fickian process,the gel present notable capacity saltation towards temperature-,pH-,ionic strength- or electric field-stimulus,the critical values of I and pH are 0.1 and 2 individually,ESR of gel appear discontinous change by leaps and bounds towards temperature stimulus, its LCST is between 42C and 45C, the reason that electric field responsibility is the existence of ionic function(-SO31-) in gel, non-uniformity of I or pH can be created since the directional shifting of the ionic function in electric field,mutual action of hydrophobic group in gel is one of major driving force in the course of deswelling.Some methods of increasing response rate of hydrogels have been researched,since pore structure be introduced in hydrogels synthesized by each of these methods,and the pore structure is favourable to water molecule passage,the hydrogels have faster temperature- and pH- responsibility,otherwise hydrogels synthesized by these methods have different swelling ratio in some degree.The result of research on AMPS and DMAEMA copolymerization kinetics be disposed by the theory of free radical copolymerization,at last,we obtain the kinetics equation of AMPS and DMAEMA copolymerization,it can be represented simply as follows: Rp [AIBN]0.58[ AMPS]1.5[DMAEMA]0.5... |
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