Study On The Properties And Network Structure Of Fatty Alcohol Polyoxyethylene Acrylate Hydrophobic Association Hydrogels

Robust hydrophobic association hydrogels(HA-gels) possess physical cross-linked network. The crosslinking points of HA-gels are transient dynamic hydrophobic association domains where “association and disassociation balance” exist. Dynamic cross-linking points endow HA-gels particular properties, such as high mechanical strength and self-healing capability. In previous research, octylphenol polyoxyethylene acrylate(OP-AC) was synthesized to use as hydrophobic monomer. AM-co-OP-AC gels were prepared via a micelle copolymerization of acrylamide(AM) and OP-AC which made progresses on mechanical strength, lifetime in water and swelling degree. Nonetheless, AM-co-OP-AC gels hydrolyzates are harmful to environment.We designed a series of eco-friendly hydrophobic hydrogels(HA-gels) through micelles copolymerization with AM as hydrophilic monomer, a little amount of fatty alcohol polyoxyethylene acrylate(AEO-AC-n-m: n is the amount of carbon chain, m is the amount of PEG chain, n,m=13,5;10,5;13,10) as hydrophobic monomer, and potassium thiosulfate(KPS) as initiator in 50? sodium dodecyl sulfate(SDS) aqueous solution. The relation of HA-gels' macro-performances and the micro network built by association domains are bound together inextricably. Researchers have studied how the monomers concentration, the sort and concentration of surfactant, pH and salt effective influence the HA-gels' micro structures and macro properties. It is well worth our exploration to figure out a method of adjusting properties of HA-gels simply, agilely, effectively.In present paper, three kinds of fatty alcohol polyoxyethylene acrylate hydrophobic monomer were synthesized: AEO-AC-13-5 possesses sheer straight alkyl chain and short PEG chain; AEO-AC-10-5 and AEO-AC-13-10 possess various branched alkyl chains, the former has short PEG chain while the latter has long PEG chain. These hydrophobic monomers have same unit in hydrophobic parts or hydrophilic parts. However, different structures of molecule chains generate various properties. We design experiments to explore HA-gels: mechanical properties(Chapter II), swelling behaviors(Chapter III) and stress relaxation behaviors(Chapter III). The key assignment is to found relation between hydrophobic monomers AEO-AC-n-m and AEO-AC-n-m-AM gels basis on Mooney-Rivlin theory, Neo-Hook equation and General Maxwell model.AEO-AC-13-5-AM gels have hydrophobic monomer AEO-AC-13-5 which possess sheer straight carbon chains(C12:C14=1 mol: 1 mol). AEO-AC-13-5 has strong hydrophobic association capability. Moreover, they can be well solubilized into SDS micelles because its structure is close to SDS. Thus, there are effective strong hydrophobic association cross-liking points in AEO-AC-13-5 gels. The hydrophilic chain in AEO-AC-13-5 is short; therefore, the water absorbing capability is weak. The molecular chain is not easy drawn out of the associated point. The AEO-AC-13-5-AM gels have strong mechanical properties(maximum stress is 270 kPa at broken); their lifetime in water is long(160 days); swelling degree in water is low(about 50 times); relaxation time is relatively long(compression relaxation time: 50000 seconds).AEO-AC-10-5-AM gels have hydrophobic monomer AEO-AC-10-5 which possesses various branched carbon chains(C10 is about 90%). Branched carbon chains have poor hydrophobic association capability. AEO-AC-10-5 monomer has weak water absorbing capability as the PEG chain is short. The AEO-AC-10-5-AM gels have weak mechanical properties; their lifetime in water is short(4~30 days); swelling degree in water is relatively high; relaxation speed is quick(compression relaxation time: 1960 seconds).AEO-AC-13-10-AM gels have hydrophobic monomer AEO-AC-13-10 which possesses various branched carbon chains(C13 is about 70%). The hydrophobic chain has steric hindrance due to solubilize into SDS micelles difficultly. Branched carbon chains C13 have poor hydrophobic association capability. On the other hand, AEO-AC-13-10 monomer has strong water absorbing capability as the PEG chain is long. The AEO-AC-13-10-AM gels have weak mechanical properties; their lifetime in water is relatively short(20~50 days); swelling degree in water is high(500 times to dry gel); relaxation time is endless(compression relaxation time: 4 hundred thousand seconds).Lastly, in Chapter V, hydrophobic association polymer AEO-AC-10-5-AM and AEO-AC-13-10-AM were prepared by branched hydrophobic monomers AEO-AC-10-5 and AEO-AC-13-10. Further discussion on “association and disassociation balance” was made to figure out the influence of monomer and surfactant to dynamic association domain through dynamic rheological tests.In conclusion,we made a more in-depth research on the structure of hydrophobic monomers,surfactant effect,mechanical properties and swelling behavior of HA-gels,and then we got a more profound understanding on the cross-linked structure and construction mechanism of HA-gels. Lastly, our HA-gels also exhibit good self-healing capability, offering great opportunities for a lot of prospective biomaterials.