Method for preparing slow-release polycarboxylate water reducer based on atom transfer radical polymerization

Abstract

The invention relates to a slow-release polycarboxylate superplasticizer preparation method based on atom transfer radical polymerization. Firstly, a macromonomer initiator is prepared through atom transfer radical polymerization of unsaturated amide micromonomers with a halogenated compound initiator, unsaturated carboxylic ester, unsaturated carboxylate micromonomers and unsaturated polyether macromonomers are initiated by a macromonomer initiator under the action of a catalyst and ligand to be subjected to atom transfer radical polymerization, and thus, the slow-release polycarboxylate superplasticizer is prepared. The method is reasonable in process, simple to operate, low in preparation cost, environmentally friendly and pollution-free, and the slow-release polycarboxylate superplasticizer prepared with the method has a slow release effect on fluidity of concrete and can effectively prevent loss of concrete slump due to long-term transportation. The polycarboxylate superplasticizer prepared with the method also has the advantages of controllable molecular weight, narrow molecular weight distribution and designable molecular structure and has greater application potentials.

Description

technical field

[0001] The invention relates to the technical field of a slow-release polycarboxylate water reducer for cement concrete, in particular to a macromonomer initiator prepared by using unsaturated amide small monomers to initiate unsaturated polyether macromonomers and A specific preparation method for preparing a slow-release polycarboxylate water reducer by atom transfer radical polymerization of small unsaturated carboxylic acid monomers. Background technique

[0002] In recent years, with the rapid development of my country's construction industry, the application problems of concrete engineering have become more and more obvious, such as the large difference of concrete raw materials affected by regions, the large slump loss during the transportation of coagulation, and the rapid evaporation of concrete moisture at high temperatures. Water reducers put forward more and higher requirements. At present, the water reducer with the best application prospect and ...

Examples

Embodiment 1

[0023] First, fill the reactor with nitrogen for 3 times, continue to fill the reactor with nitrogen after excluding oxygen to maintain the nitrogen atmosphere in the reactor, and then add 7.1g of acrylamide, 7.1g of toluene, 0.16g of 2,2-bipyridine, 0.14g of bromide Cuprous, 0.2g ethyl 2-bromopropionate, and stirred for 5 minutes during each addition, heated up to 90°C for atom transfer radical polymerization, and reacted for 5 hours to obtain a macromonomer initiator; Add 9.4g of sodium acrylate, 17.2g of methyl acrylate, and 50g of allyl polyoxyethylene ether (molecular weight=500) in sequence, and then repeat the freeze-thaw cycles of freezing-nitrogen-filling-thawing 3 times, and continue filling with nitrogen to maintain the nitrogen atmosphere. Then add 100g of toluene, 0.16g of 2,2-bipyridine, 0.14g of cuprous bromide, and the macromonomer initiator obtained before, and stir for 5 minutes during each addition, and heat up to 50°C for atom transfer free radical Polymeri...

Embodiment 2

[0025] The polycarboxylate superplasticizer with a concentration of 40% obtained in Example 1 was stored at 7° C. for 30 days, and its implementation effect was measured.

Embodiment 3

[0027] First, fill the reactor with nitrogen for 5 times, continue to fill the reactor with nitrogen after removing oxygen to keep the reactor in a nitrogen atmosphere, then add 12.7g of N-isopropylmethacrylamide, 12.7g of acetone, 0.248g of tetramethylethylene glycol in sequence Amine, 0.645g of ferrous bromide, 0.15g of 2-bromopropionamide, and stirring for 15 minutes during each addition, the temperature was raised to 70°C for atom transfer radical polymerization, and the reaction was carried out for 7 hours to obtain a macromonomer initiator; Add 16.5g of potassium acrylate, 20g of ethyl acrylate, and 100g of methylalkenyl polyoxyethylene ether (molecular weight=1000) to the reactor successively, and then repeat the freeze-thaw cycles of freezing-nitrogen-filling-thawing 5 times, and then continue to fill with nitrogen Keep the nitrogen atmosphere, then add 200g of acetone, 0.017g of tetramethylethylenediamine, 0.032g of ferrous bromide, and the macromonomer initiator obtai...

technical field

[0001] The invention relates to the technical field of a slow-release polycarboxylate water reducer for cement concrete, in particular to a macromonomer initiator prepared by using unsaturated amide small monomers to initiate unsaturated polyether macromonomers and A specific preparation method for preparing a slow-release polycarboxylate water reducer by atom transfer radical polymerization of small unsaturated carboxylic acid monomers. Background technique

[0002] In recent years, with the rapid development of my country's construction industry, the application problems of concrete engineering have become more and more obvious, such as the large difference of concrete raw materials affected by regions, the large slump loss during the transportation of coagulation, and the rapid evaporation of concrete moisture at high temperatures. Water reducers put forward more and higher requirements. At present, the water reducer with the best application prospect and ...

Examples

Embodiment 1

[0023] First, fill the reactor with nitrogen for 3 times, continue to fill the reactor with nitrogen after excluding oxygen to maintain the nitrogen atmosphere in the reactor, and then add 7.1g of acrylamide, 7.1g of toluene, 0.16g of 2,2-bipyridine, 0.14g of bromide Cuprous, 0.2g ethyl 2-bromopropionate, and stirred for 5 minutes during each addition, heated up to 90°C for atom transfer radical polymerization, and reacted for 5 hours to obtain a macromonomer initiator; Add 9.4g of sodium acrylate, 17.2g of methyl acrylate, and 50g of allyl polyoxyethylene ether (molecular weight=500) in sequence, and then repeat the freeze-thaw cycles of freezing-nitrogen-filling-thawing 3 times, and continue filling with nitrogen to maintain the nitrogen atmosphere. Then add 100g of toluene, 0.16g of 2,2-bipyridine, 0.14g of cuprous bromide, and the macromonomer initiator obtained before, and stir for 5 minutes during each addition, and heat up to 50°C for atom transfer free radical Polymeri...

Embodiment 2

[0025] The polycarboxylate superplasticizer with a concentration of 40% obtained in Example 1 was stored at 7° C. for 30 days, and its implementation effect was measured.

Embodiment 3

[0027] First, fill the reactor with nitrogen for 5 times, continue to fill the reactor with nitrogen after removing oxygen to keep the reactor in a nitrogen atmosphere, then add 12.7g of N-isopropylmethacrylamide, 12.7g of acetone, 0.248g of tetramethylethylene glycol in sequence Amine, 0.645g of ferrous bromide, 0.15g of 2-bromopropionamide, and stirring for 15 minutes during each addition, the temperature was raised to 70°C for atom transfer radical polymerization, and the reaction was carried out for 7 hours to obtain a macromonomer initiator; Add 16.5g of potassium acrylate, 20g of ethyl acrylate, and 100g of methylalkenyl polyoxyethylene ether (molecular weight=1000) to the reactor successively, and then repeat the freeze-thaw cycles of freezing-nitrogen-filling-thawing 5 times, and then continue to fill with nitrogen Keep the nitrogen atmosphere, then add 200g of acetone, 0.017g of tetramethylethylenediamine, 0.032g of ferrous bromide, and the macromonomer initiator obtai...

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