氧化石墨烯基納米復(fù)合水凝膠的制備及其性能研究
發(fā)布時(shí)間：2018-10-22 11:05
【摘要】：高分子水凝膠是一類具有三維網(wǎng)絡(luò)結(jié)構(gòu)的水溶脹型功能高分子材料,其網(wǎng)絡(luò)結(jié)構(gòu)的主鏈或側(cè)鏈連有諸如羥基、酰胺基、羧基、磺酸基等親水基團(tuán),能夠吸附相當(dāng)于自身質(zhì)量幾十到幾百倍甚至上千倍的水或水溶液。并且在一定壓力條件下,仍具有良好的吸水、保水性能。而在實(shí)際的使用過程中,由于水體的金屬離子、p H值等外界因素使得高分子水凝膠網(wǎng)絡(luò)塌陷而造成材料失去吸水保水能力,成為制約其實(shí)際應(yīng)用的瓶頸因素。研究證明,向高分子水凝膠引入納米填充體是提高其吸水性和耐鹽性的一種有效手段。氧化石墨烯(GO)是一種單原子層厚度的二維納米材料,它具有石墨烯的穩(wěn)定結(jié)構(gòu)和良好的力學(xué)性能,同時(shí)由于其含有大量的親水性含氧官能團(tuán),在水中具有極好的分散性,為GO與其它親水性物質(zhì)在水相中進(jìn)行反應(yīng)、摻雜等制備納米復(fù)合材料提供了可能�；诖�,本論文以GO或化學(xué)改性的GO為納米填充體,通過原位聚合或共聚等方法制備一系列GO基納米復(fù)合水凝膠,研究GO對(duì)納米復(fù)合水凝膠物化性能以及吸水、耐鹽等溶脹性能的影響。在此基礎(chǔ)上,研究其在純水、鹽溶液環(huán)境下,納米復(fù)合水凝膠網(wǎng)絡(luò)中的GO片層對(duì)聚合物網(wǎng)絡(luò)溶脹、塌陷產(chǎn)生的影響,以期構(gòu)建納米復(fù)合水凝膠結(jié)構(gòu)-性能關(guān)系。主要研究內(nèi)容和結(jié)果包括:(1)以GO為填充體,丙烯酸、丙烯酰胺為聚合單體,N,N-亞甲基雙丙烯酰胺為交聯(lián)劑,過硫酸銨為引發(fā)劑,分別制備了聚丙烯酸-氧化石墨烯(PAA-GO)和聚丙烯酰胺-氧化石墨烯納米復(fù)合水凝膠(PAM-GO)。GO納米片在聚合物中分散均勻,納米復(fù)合水凝膠呈現(xiàn)出無定形結(jié)構(gòu)。結(jié)果發(fā)現(xiàn),添加極小量的GO(0.073 wt%)就可以大大的提高了水凝膠的吸水能力,主要?dú)w因于親水的GO納米片可有效的改善水凝膠的網(wǎng)絡(luò)結(jié)構(gòu),從而能夠吸收更多的水分;引發(fā)劑和交聯(lián)劑的加入量對(duì)納米復(fù)合水凝膠網(wǎng)絡(luò)結(jié)構(gòu)的影響則與純有機(jī)水凝膠相似:隨著引發(fā)劑加入量的增加,納米復(fù)合水凝膠的吸水能力先增加后減小,而交聯(lián)劑的加入量與納米復(fù)合水凝膠的吸水能力成反比。在耐鹽性方面,GO納米片在納米復(fù)合水凝膠網(wǎng)絡(luò)結(jié)構(gòu)中起到“非離子”性填充體的作用,從而有效地防止了網(wǎng)絡(luò)結(jié)構(gòu)的坍塌,提高了納米復(fù)合水凝膠的耐鹽性。通過有機(jī)溶液中溶脹行為的研究發(fā)現(xiàn),GO納米片的引入也能夠改善PAA-GO、PAM-GO納米復(fù)合水凝膠在有機(jī)溶劑/水體系中的結(jié)構(gòu)坍塌和變形。一方面,GO表面的親水官能團(tuán)與聚合物鏈上的官能團(tuán)結(jié)合,提高了整個(gè)聚合物網(wǎng)絡(luò)的強(qiáng)度,另一方面,GO的二維納米結(jié)構(gòu)能夠起到“house-of-cards”的作用,有效地阻止了自由水分子從網(wǎng)絡(luò)中被“擠出”。(2)以GO為填充體,N,N-亞甲基雙丙烯酰胺為交聯(lián)劑,過硫酸銨為引發(fā)劑,丙烯酸、丙烯酰胺共聚制備了聚(丙烯酸-co-丙烯酰胺)/氧化石墨烯(PAAM-GO)納米復(fù)合水凝膠,呈現(xiàn)層狀三維網(wǎng)狀結(jié)構(gòu)。在凝膠的形成過程中引發(fā)劑含量、單體比例、交聯(lián)劑含量及GO濃度對(duì)于制備得到的PAAM-GO納米復(fù)合水凝膠的吸附性能均有很大的影響。在引發(fā)劑含量為64 mg、交聯(lián)劑含量為12.8 mg、單體(丙烯酸:丙烯酰胺)摩爾比例為0.5、GO濃度為0.5 mg m L-1時(shí)制備得到的PAAM-GO納米復(fù)合水凝膠對(duì)于水的吸附量最大為197 g g-1。在聚合體系中加入GO可以使水凝膠形成更加穩(wěn)定的三維網(wǎng)絡(luò)結(jié)構(gòu),在外界溶液條件發(fā)生變化時(shí)有效防止水凝膠網(wǎng)絡(luò)結(jié)構(gòu)的坍塌,進(jìn)而提高了納米復(fù)合水凝膠的綜合吸附性能。(3)利用重氮化反應(yīng)對(duì)GO表面進(jìn)行改性,以其為填充體,N,N-亞甲基雙丙烯酰胺為交聯(lián)劑,過硫酸銨為引發(fā)劑,丙烯酸為聚合單體制備了聚丙烯酸-改性GO納米復(fù)合水凝膠。改性GO與PAA具有良好的兼容性,改性GO的加入有效地提高了納米復(fù)合水凝膠的綜合吸附性能。(4)通過原位聚合方法,在大氣氛圍下,通過摻雜十八烷基胺改性的氧化石墨烯(GO/ODA),合成了具有耐鹽性的聚丙烯酰胺/聚乙二醇-十八烷基胺改性GO互穿網(wǎng)絡(luò)水凝膠(PAM/PEG-GO/ODA)。摻雜GO/ODA可顯著提高PAM/PEG-GO/ODA的耐鹽性和吸水性能。其中,在Ca Cl2水溶液中吸水倍率可提高60%以上。當(dāng)GO/ODA添加量為5 wt%時(shí),其耐鹽性提高一倍,達(dá)到61g g-1。PAM/PEG-GO/ODA具有親水疏油性質(zhì),對(duì)油品中的水具有優(yōu)異的選擇性,除水率達(dá)到99%以上。(5)制備了聚乙烯醇/聚乙烯吡咯烷酮-GO互穿網(wǎng)絡(luò)水凝膠(PVA/PVP-GO),通過冷凍干燥法制造出豐富貫穿孔結(jié)構(gòu)。GO含量對(duì)PVA/PVP-GO的孔道結(jié)構(gòu)有較大影響,在GO濃度較低時(shí)PVA/PVP-GO呈現(xiàn)出許多較大的孔道,但隨著GO濃度的增大復(fù)合凝膠的孔道結(jié)構(gòu)明顯減小呈現(xiàn)出貫穿的峰窩狀結(jié)構(gòu)。相比于聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)水凝膠而言,與GO復(fù)合的PVA/PVP水凝膠在相同條件下具有更優(yōu)異的吸水性能,GO的加入有效地改善了PVA/PVP結(jié)構(gòu)的坍塌和變形,這說明在PVA/PVP水凝膠體系中加入GO可以明顯提高PVA/PVP水凝膠的耐鹽性。利用其大孔結(jié)構(gòu)和表面親水疏油性質(zhì),PVA/PVP-GO可用來過濾柴油中的水,含水率由0.094 g g-1下降到37.95 ppm,除水率達(dá)到99.95%,PVA/PVP-GO對(duì)油品中的水具有優(yōu)異的選擇性。
[Abstract]:High molecular hydrogel is a kind of water-swellable functional polymer material with three-dimensional network structure, capable of adsorbing water or an aqueous solution equivalent to tens to hundreds or even thousands of times of its own mass. and has good water absorption and water retention performance under certain pressure conditions. In the actual use process, because of the metal ion, p H value and other external factors of the water body, the polymer hydrogel network collapses to cause the material to lose water-absorbing and water-retaining ability, and becomes the bottle-neck factor restricting its practical application. It has been proved that the introduction of nano-fillers into polymer hydrogels is an effective method to improve water absorption and salt tolerance. the graphene oxide (GO) is a two-dimensional nano material with a single atomic layer thickness, It is possible to prepare nano-composites by reacting GO with other hydrophilic substances in aqueous phase. Based on this, GO or chemically modified GO was used as a nano-filler, and a series of GO-based nanocomposite hydrogels were prepared by in-situ polymerization or copolymerization, and the effects of GO on physical and chemical properties of nano-composite hydrogel and swelling properties of water absorption and salt resistance were studied. On the basis of this, the effect of GO layer on swelling and collapse of polymer network was studied under pure water and salt solution environment, with a view to constructing nano composite hydrogel structure-performance relationship. The main research contents and results are as follows: (1) GO as filler, acrylic acid, polymerization monomer as polymerization monomer, N, N-methylene bispecific as cross-linking agent, over-polymerization as initiator, Polyacrylic acid-graphene oxide (PAA-GO) and poly (ethylene oxide-graphene) nano composite hydrogel (PAM-GO) were prepared respectively. The GO nano-sheets were dispersed uniformly in the polymer, and the nano composite hydrogel exhibited an amorphous structure. As a result, it was found that adding a very small amount of GO (0.073 wt%) can greatly improve the water-gel ability of hydrogel, mainly due to hydrophilic GO nano-sheet can effectively improve the network structure of hydrogel, so that more water can be absorbed; the influence of initiator and cross-linking agent on the network structure of nano composite hydrogel is similar to that of pure organic hydrogel, and the addition amount of the cross-linking agent is inversely proportional to the swelling capacity of the nano composite hydrogel. In the aspect of salt tolerance, GO nano-sheets play a role in the network structure of nano-composite hydrogel "Non-ionic" and the salt tolerance of the nano composite hydrogel is improved. The research of swelling behavior in organic solution shows that the introduction of GO nano-sheet can also improve the structure and deformation of PAA-GO, PAM-GO nano composite hydrogel in organic solvent/ water system. On the one hand, the hydrophilic functional group on the GO surface is combined with the functional group on the polymer chain, so that the strength of the whole polymer network is improved; and on the other hand, the two-dimensional nano structure of the GO can play the role of 鈥渉ouse-of-cards鈥，
本文編號(hào)：2286975
[Abstract]:High molecular hydrogel is a kind of water-swellable functional polymer material with three-dimensional network structure, capable of adsorbing water or an aqueous solution equivalent to tens to hundreds or even thousands of times of its own mass. and has good water absorption and water retention performance under certain pressure conditions. In the actual use process, because of the metal ion, p H value and other external factors of the water body, the polymer hydrogel network collapses to cause the material to lose water-absorbing and water-retaining ability, and becomes the bottle-neck factor restricting its practical application. It has been proved that the introduction of nano-fillers into polymer hydrogels is an effective method to improve water absorption and salt tolerance. the graphene oxide (GO) is a two-dimensional nano material with a single atomic layer thickness, It is possible to prepare nano-composites by reacting GO with other hydrophilic substances in aqueous phase. Based on this, GO or chemically modified GO was used as a nano-filler, and a series of GO-based nanocomposite hydrogels were prepared by in-situ polymerization or copolymerization, and the effects of GO on physical and chemical properties of nano-composite hydrogel and swelling properties of water absorption and salt resistance were studied. On the basis of this, the effect of GO layer on swelling and collapse of polymer network was studied under pure water and salt solution environment, with a view to constructing nano composite hydrogel structure-performance relationship. The main research contents and results are as follows: (1) GO as filler, acrylic acid, polymerization monomer as polymerization monomer, N, N-methylene bispecific as cross-linking agent, over-polymerization as initiator, Polyacrylic acid-graphene oxide (PAA-GO) and poly (ethylene oxide-graphene) nano composite hydrogel (PAM-GO) were prepared respectively. The GO nano-sheets were dispersed uniformly in the polymer, and the nano composite hydrogel exhibited an amorphous structure. As a result, it was found that adding a very small amount of GO (0.073 wt%) can greatly improve the water-gel ability of hydrogel, mainly due to hydrophilic GO nano-sheet can effectively improve the network structure of hydrogel, so that more water can be absorbed; the influence of initiator and cross-linking agent on the network structure of nano composite hydrogel is similar to that of pure organic hydrogel, and the addition amount of the cross-linking agent is inversely proportional to the swelling capacity of the nano composite hydrogel. In the aspect of salt tolerance, GO nano-sheets play a role in the network structure of nano-composite hydrogel "Non-ionic" and the salt tolerance of the nano composite hydrogel is improved. The research of swelling behavior in organic solution shows that the introduction of GO nano-sheet can also improve the structure and deformation of PAA-GO, PAM-GO nano composite hydrogel in organic solvent/ water system. On the one hand, the hydrophilic functional group on the GO surface is combined with the functional group on the polymer chain, so that the strength of the whole polymer network is improved; and on the other hand, the two-dimensional nano structure of the GO can play the role of 鈥渉ouse-of-cards鈥，
本文編號(hào)：2286975
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