羧酸型共聚物：合成與對於砂漿中氧化石墨烯分散性的影響

Abstract

本篇研究目標是合成一種羧酸系兩性離子型共聚物PDA(聚(N,N,N-二甲基((羧酸)丙烯醯氧基乙基)丁酸鈉-丙烯醯胺)，作為共聚物用來改善氧化石墨烯在水泥基材料的分散性以提升試體的機械性質。先使用馬來酸酐和N,N-二甲基胺乙醇合成DME(二甲基胺乙基氧羰基丙烯酸)，再與4-氯丁酸反應得到單體DCB(N,N,N-二甲基((羧酸)丙烯醯氧基乙基)丁酸鈉)，最後使用過硫酸銨(APS)為起始劑，與不同比例丙烯醯胺(AM)經由自由基聚合反應合成得到兩性離子型共聚物PDA，PDA經由FTIR和1H-NMR光譜鑑定其結構，以GPC測定其分子量。另外，使用Hummers法將石墨烯氧化成氧化石墨烯(GO)。將PDA加入含氧化石墨烯的水溶液中，透過沉降體積、粒徑分布、界達電位與黏度實驗測試，探討PDA對於水溶液中GO的分散效果。測試結果顯示，在人工孔隙溶液中共聚物對於GO的沉降時間隨著AM/DCB比例的增加呈現先增後減的趨勢，PDA在AM/DCB=4時有最長的沉降時間；另外，GO的沉降時間隨著PDA分子量的上升或添加量的增加而增長，因此PDA41添加量為20 wt%時，GO的沉降時間為最長達65小時，此時溶液的黏度為最低(2.88 mPa‧s)，溶液中GO的D50粒徑為最小、負界達電位為最大，分別為287 nm和-28.2 mV。因此在所合成的共聚物中PDA41有最好的分散效果。將PDA41加入含氧化石墨烯的水泥砂漿中，測試砂漿試體的抗壓強度與抗彎強度。結果顯示，添加20 wt%的PDA41與0.05 wt%的GO的水泥砂漿試體，在28天的抗壓強度為34.7 MPa，抗彎強度為6.73 MPa，與未添加共聚物的控制組相比提升了57%與99%。This thesis is to synthesize a zwitterionic carboxylate copolymer PDA (Poly(N,N,N-dimethyl((carboxylate) acryloyloxyethyl) butyrate-co-acrylamide)) as a dispersant to improve the dispersion of graphene oxide (GO) in cement-based materials and the mechanical properties of mortar. First, maleic anhydride and N,N-dimethylaminoethanol was used to synthesize DME(3-((2-(dimethylamino)ethoxy)carbonyl)acrylic acid). Then, DME was reacted with sodium 4-chlorobutyric acid to obtain the monomer DCB(N,N,N-dimethyl((carboxylate) acryloyloxyethyl) butyrate). Thereafter, PDA copolymer was prepared from DCB and acrylamide(AM) through free radical polymerization by using ammonium persulphate as an initiator. FT-IR and 1H-NMR were used to identify the structure of PDA, and GPC was used to determine the molecule weight of the prepared polymer. Besides, graphene oxide was prepared from graphene using the Hummers method.The dispersion property of PDA was evaluated through the sedimentation test, size distribution, zeta potential and viscosity measurements. The results indicated the sedimentation time of GO in the artificial pore solution increased with AM/DCB ratio of polymer first, reached a maximum value at AM/DCB=4, and then decreased afterwards. Increase of the molecular weight of PDA or polymer dosage increased the sedimentation time of GO in the artificial pore solution. Apparently, PDA41 which has AM/DCB=4 and the highest molecular weight showed the best performance. GO in the pore solution with 20 wt% PDA41 was found to have the smallest particle size and highest absolute value of zeta potential of GO, and longest sedimentation time. Finally, the compressive and flexural strength of mortar with 0.05 wt% of graphene oxide and 20 wt% of PDA41 at 28days were 34.7 MPa and 6.73 MPa, which were 57% and 99% increased relative to the mortar without any dispersant or GO present.