Xie Zili nodded and said, "Director Li, do we really want to engage in polycarboxylate superplasticizer?" Although foreign countries have been developing polycarboxylic acid superplasticizers since the 80s. However, only Japan is known to have succeeded and is about to enter industrial production. Other countries can only stay in the real yàn room, which is not easy! ”

Li Ruoyu said with a smile: "The difficulty is indeed very great, and it is precisely because of the difficulty that we need our concrete technology research and development center!" Without high-performance superplasticizers, how can we develop high-performance concrete? At the beginning, Japanese scholars used the reactive active polymer synthesized by guò as a slump loss control agent for concrete, and later they really designed the most effective molecular structures in the mechanism of action of dispersed cement, so that the water reduction and dispersion effect and fluidity retention effect of the admixture can be greatly improved. In 1986, Japanese experts first successfully developed a polycarboxylic acid superplasticizer, and the ultimate goal of the research of polycarboxylic acid superplasticizer is to copolymerize the unsaturated monomer under the action of the initiator, and link the side with active groups to the main chain of the polymer, so that it has the functions of efficient water reduction, slump loss control and shrinkage resistance, and does not affect the coagulation and hardening of cement. This type of superplasticizer is broadly divided into olefin/maleic anhydride polymers and acrylic/methacrylate polymers. ”

Zeng Li, another female R&D technician, continued: "Director, your decision is really correct. I have heard that the polycarboxylic acid high-performance superplasticizer is a new high-efficiency superplasticizer with unique properties and no pollution, which is an ideal admixture for the preparation of high-performance concrete. If the Japanese can develop it, why can't we? I am confident that under the leadership of the Director, we will be able to accomplish this difficult task. ”

Li Ruoyu laughed and said, "That's right! Comrade Zeng Li is right, why are we worse than the Japanese? No, we will definitely do better than the Japanese, the Japanese were able to invent a polycarboxylate superplasticizer, but we can make a better polycarboxylate superplasticizer than the Japanese through hard work! ”

Li Ruoyu knows that after 1995, the use of polycarboxylic acid superplasticizer in Japan has exceeded that of the second generation of naphthalene superplasticizer, and there are many varieties, models and brand names. In particular, the application of a large number of high-strength and high-fluidity concrete has driven the technical development and application level of polycarboxylic acid superplasticizer. The manufacturers of polycarboxylic acid superplasticizer in Japan mainly include Kao, Bamboo Oil, NMB Co., Ltd. and Fujisawa Pharmaceutical, etc., and the annual production of various types of concrete with such superplasticizer exceeds 10 million cubic meters, and there is a growing trend year by year. At the same time, the research and application of polycarboxylic acid superplasticizers in other countries have been gradually strengthened. Although Japan is the earliest and most successful country in the development and application of polycarboxylic acid superplasticizers, North America and Europe also attach great importance to the research of polycarboxylic acid superplasticizers. Moreover, the research of polycarboxylic acid superplasticizer has also developed from the first-generation methacrylic acid/methyl olenoate copolymer, to the second-generation propylene ether copolymer, and then to the third-generation amide/imide type, and even after the arrival, the development of the fourth-generation polyamide-polyethylene glycol branched new high-efficiency superplasticizer.

In Li Ruoyu's previous life, the first to develop and apply polycarboxylic acid high-performance superplasticizer in China was the Shanghai Institute of Building Research, whose polycarboxylic acid superplasticizer was successfully applied to the Shanghai maglev train track girder project, Donghai Bridge and Hangzhou Bay Bridge and other projects.

Later, the research on polycarboxylic acid superplasticizer began to be paid attention to in China, and there were more research units in this area. Since 2000, the Department of Civil Engineering of Huaqing University has been conducting a series of experimental studies on the synthesis method of polycarboxylic acid-based high-performance superplasticizer. Other units, such as South China University of Technology, East China University of Science and Technology, Gongji University, Fuming University, China Academy of Building Materials Science, etc., have also carried out exploration and research on the structure, mechanism, preparation, performance evaluation and application of polycarboxylic acid-based high-performance superplasticizers, and have achieved certain results. In particular, China later invented the method of synthesizing polycarboxylic acid superplasticizer at room temperature, which greatly advanced the industrial production and popularization of polycarboxylic acid.

Xie Zili said: "But how should we carry out R&D work? At present, only the Japanese have this technology, and it is impossible for us to obtain technical information in this area from Japan. If you're completely on your own, you don't know where to start! ”

Li Ruoyu smiled: "You don't have to worry about this! The superplasticizer is used to hinder or destroy the flocculation structure of cement particles through guò surface activity, complexation, electrostatic repulsion and stereo-repulsion. The ideal structure of a high-performance superplasticizer should be a polymer with linear, multi-branched, hydrophobic and hydrophilic groups, with the hydrophobic group chain being light and short, and the hydrophilic group chain being heavy and long. In the cement slurry, it is like a comb, the hydrophobic group is firmly nailed to the surface of the cement particles, and the hydrophilic group extends to the aqueous solution, which has both a group that produces electrostatic repulsion and a group that produces three-dimensional repulsion. Polycarboxylate superplasticizer is copolymerized with three monomers: polyethylene glycol monoester acrylate, maleic anhydride and sodium acrylic sulfonate. All three monomers can be synthesized in the laboratory using currently available chemical products. ”

Xie Zili said excitedly: "Ah, director, why didn't you do it early, it made me worry for a long time!" Let's talk about how to synthesize! We should immediately carry out experimental research and strive to develop our polycarboxylic acid admixtures as soon as possible. ”

Li Ruoyu smiled: "Don't worry! I'll send you a set of technical information so you know what to do. Before I do that, let me say a few words. The preparation method of polyethylene glycol monoester acrylate is very simple, that is, a certain amount of polyethylene glycol, dodecylbenzene sulfonic acid, and hydroquinone are added to the three-mouth bottle. Acrylic acid was added at 110~120 °C, and after the dropwise addition was completed, the acrylic acid was kept at 120 °C for 2.5h. The reaction solution was depressurized to evaporate the by-product water, and the reaction at this temperature for 2h slowed down the speed of water removal. The constant temperature of 130°C is the end point of the reaction when the amount of water obtained by the vacuum reaction is close to the theoretical value; Under vacuum conditions, it is cooled to below 40 °C, and the finished product is discharged. In the second step, add a certain amount of distilled water and anhydrous sodium sulfite to the three-mouth bottle, heat and stir to dissolve it, start to add human chloropropylene at 45 °C, and after the dropwise addition is completed, the temperature is raised to 47 °C for 3h; The reactants were depressurized, evaporated at 40 °C, and then washed with absolute ethanol, and filtered while hot; The filtrate was depressurized, steamed at 40 °C until nearly dry, and poured out and placed in a beaker for crystallization. The third step is the synthesis of maleic anhydride-PA-SAS copolymer, add distilled water and maleic anhydride to the three-mouth bottle, heat and stir to dissolve it, and when the temperature reaches 60 °C, start to add human PA and SAS solution, and add human persulfate at the same time. After the dropwise addition, the temperature is raised to 85 °C for 3~5h, and the discharge is the polycarboxylic acid superplasticizer we need. Of course, in order to obtain a polycarboxylate superplasticizer with excellent performance, it is also necessary to conduct a comparative study on the dosage and test temperature of various materials in the test. ”

Is polycarboxylic acid synthesis so simple? Everyone was a little dumbfounded!