| N-isopropylacrylamide, which has both hydrophilic acylamino and hydrophobic isopropyl, receives much concern in recent years due to its polymers show favorable thermosensitivity. It has been used extensively in drug delivery , material separation , enzyme immobilization and immunoanalysis. To meet some applications, such as mechanical valve, bio-sensor and artificial muscle, the rapid response rate and high compression modulus are important parameters for hydrogels. Reasearching them is a very meaningful and valuable work.Gels with rapid response rate can be synthesized by using pore-forming agent. The freezing method can be used to synthesis the gels with rapid response rate or high-intensity.In this thesis, P(NIPAm-co-AAm) copolymerized gels and PNIPAm homopolymerized gels were researched. The effect of some factors,such as monomer concentration, crosslinker concentration, kinds and amount of PEG, cold-treating and frozen-before time were investigated.Water-soluble macromolecules poly(ethylene glycol)(PEG) with different molecular weight were used as pore-forming agents during the reaction process. Porous P(NIPAm-co-AAm) gels were polymerized successfully at 18℃. The comparison between PNA and PN were analyzed. the results showed that PNA gels has higher Lower Critical Solution Temperature(LCST) due to it leads-in more hydrophilic groups(-CONH-). PEG were just as pore-forming agent, they have no effect on the LCST of gels because of that no new functional group leaded in during the polymerization process. Comparing with traditional PNA gels, the porous PNA gels had faster swelling and deswelling rate. It's equilibrium swelling ratio was higher at low temperature environment and lower at high temperature environment. However, comparing with PN gels, PNA gels had faster swelling rate and slower deswelling rate due to it had more hydrophilic groups, it's equilibrium swelling ratio was lower at low temperature environment and higher at high temperature environment. However, the phenomenon of acceleration during swelling process was easier to be observed on porous PN than porous PNA. The PNA gels had higher compression modulus at 20℃than that of the PN gels.In this thesis, P(NIPAm-co-AAm) and PNIPAm gels were polymerized successfully by freezing method. In addition,the traditional gels were cold-treated. The effect of cold-treating method and frozen-before time on properties of the gels was investigated. Cold-treating method: the first stage, polymerized at 18℃; the second stage, kept on polymerizing at -18℃. The controlling of frozen-before time at 18℃was very important. Super-pores gels could be synthesized if frozen-before time is shorter than the gelation time. Frozen before gelation point , the gels display large interconnecting pores structure and this system of channels make it possible that a fast convective water transport, inwards as well as outwards, in such gels. The hydrogels show a very fast swelling/deswelling rate and very low compression modulus. Frozen after gelation point,the gels may have remarkable compression modulus due to the interaction of water molecule and strengthened polymer chains. Therefore, strong intensity gels could be synthesized if frozen-before time is longer than the gelation time. Prolonging frozen-before time,we can find that these gels frozen at different time display a compression modulus curve with three platform periods. Among the three, one is high and the other two are low. At the end of the curve, gels'compression modulus is closed to that of traditional ones.During the process of cold-treating, the random polymer chains may be regulated by the ice crystal and thus turn into a relatively regular arrangement. The main change is deswelling rate of the gels become faster. In addition:the effect of reintegration closely relate to the swelling rate. The swelling rate is higher, the effect better. However, the other properties of the gels almost unchanged by this method.
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