Polycarboxylic water reducer having reducing function, synthesis method and application method thereof

The invention belongs to the technical field of construction materials, and specifically relates to a polycarboxylic water reducer having the reducing function, a synthesis method and an application method thereof. The synthesis method comprises the following steps: selecting polyacrylic acid, amine compounds with amide groups, polyethylene glycol, p-toluenesulfonic acid, sodium hydroxide and water as raw materials, weighing the polyacrylic acid and the amine compounds with amide groups according to the mass ratio, orderly adding to a reaction kettle, mixing, and stirring; introducing protective nitrogen gas to the reaction kettle, plugging a water separator and a condenser pipe, and reacting at 100-240 DEG C for 0.5-5 hours; adding the polyethylene glycol and the p-toluenesulfonic acid which are weighed according to the mass ratio to the polymer while stirring to be subjected to the esterification reaction at 50-120 DEG C for 2-8 hours; and adding water to the ester to prepare a solution, adding the sodium h