Fabrication and properties of dinotefuran/attapulgite/poly (N-isopropylacrylamide) hydrogels regulated by surfactant

Firstly, the surfactant cetyltrimethylammonium bromide (CTAB) and 1-hexadecyl-3-methylimidazolium chloride monohydrate (HMCM) were intercalated into attapulgite (AP) to obtain CTAB-AP and HMCM-AP complexes, respectively, and then pesticide dinotefuran (DIN) was introduced into the complexes to prepare DIN/CTAB-AP (HMCM-AP) hybrids, finally the hybrids was added into N-isopropylacrylamide (NIPAM) solution to obtain DIN/CTAB-AP(HMCM-AP)/PNIPAM hydrogels through the free radical polymerization. Their structures were systematically characterized by XRD, FTIR, TGA , SEM and BET. The effect of hybrids content, crosslinker concentration and pH on the hydrogel was investigated and analyzed. The existence of DIN and surfactant molecules in the hydrogels was confirmed. Fabrication mechanism of DIN hydrogels was put forward. Release behaviors of the hydrogels were investigated in different release mediums and temperatures. For DIN/CTAB-AP/PNIPAM, DIN release amount increased from 79.5 % at 20°C to 97.7 % at 30°C. For DIN/CTAB-AP/PNIPAM and DIN/HMCM-AP/PNIPAM ( p  = 4, 9.3) hydrogels, the release rates are much slower in pH= 5.0 than pH= 9.0. The release behaviors were well fitted by pseudo second-order and Ritger-Peppas models. Bioassays revealed extended efficacy against aphids (73 % mortality on third day for the third inoculation), suggesting a long duration and control effect of the hydrogels on the pest compared to the DIN water dispersible granules. This study provided a new method to improve the utilization efficiency of pesticide, and the hydrogel can be potentially used as a pesticide delivery system.