Solution Behavior Of Sulfonated Alkali Lignin Polyethenoxy Ether And Its Applications In Two Pesticide Formulations

With the enhancement of environmental protection consciousness, the environmentally friendly, low toxicity sustained release microcapsule suspending agent(CS) and water-based pesticide aqueous suspension concentrate(SC) become direction of the pesticide formulations. This dissertation aimed at solving the problem of too short effective reaction time of abamectin(AVM) and particles growth phenomenon of high concentrations imidacloprid SC. Therefore, sulfonated alkali lignin polyethenoxy ether(SAL-PEG) prepared with alkali lignin was used as wall material of abamectin-loaded microcapsule(AVM-CS) and dispersant of 40% imidacloprid SC, which studied the potential of modified lignin for high value utilization of lignin and for reducing pesticide pollution to the environment.SALs with different sulfonic group contents were prepared through sulfomethylation reaction. SAL-PEGs with different crosslinking degrees and molecular weights were synthesized by grafting SAL with polyethylene glycol(PEG) long chains. SAL-PEGs were analyzed by UV spectrogram, gel permeation chromatography, IR spectrogram and 1H NMR spectrogram. It was found that sulfonic acid group and PEG chain had been grafted in AL.The effects of the sulfonic acid group content and the PEG nonionic long chain on the behaviors of SAL and SAL-PEG in solution were studied by dynamic light scattering(DLS). It was demonstrated that the aggregation behavior existed in 1.0 g/L SAL aqueous solution. Furthermore, the degree of aggregation decreased with the increasing sulfonic acid group content of SAL, because the more sulfonic acid groups caused the increasing molecular stretch degree of SAL. The addition of NaCl made the molecular configuration of SAL become compact in solution, and the aggregates of SAL were disaggregated evidently. While SAL-PEG mainly took the form of single molecule in 1.0 g/L aqueous solution, and the hydrodynamic radius(Rh) of SAL-PEG was proportional to its molecular weight and the crosslinking degree. The addition of NaCl made the PEG nonionic long chain of SAL-PEG become compact severely in solution, and Rh of SAL-PEG showed a significantly down trend, which was proportional to its molecular weight and cross-linking degree, although the degree of aggregation of SAL-PEG was still weak.The AVM-CS was prepared through electrostatic self-assembly using SAL-PEG and Polyethyleneimine(PEI) as shell materials. The effects of crosslinking and self-assembly conditions on drug loading, entrapment efficiency and release behaviors of CS were studied. The factors of crosslinking conditions included agent, temperature, pH, concentration and dosage. The elements of self-assembly conditions contained dosage of AVM, concentration of wall materials, pH and NaCl concentration. It was revealed that the key of preparation of CS with sustained release capability was the crosslinking reaction. Meanwhile, drug loading of CS was related to dosage of AVM and entrapment efficiency was 50%~60%. Under the optimal reaction conditions of crosslinking conditions(T=30℃, pH=8, 8 mL dosage per 20 g wall material) and self-assembly conditions(pH=8, 1 mol/L NaCl in solution), the releasing time could reach 72 h, which achieved the level of commercial polyurethane CS.At the same time, SAL-PEG and SAL were used as dispersant of dimethomorph and imidacloprid SC. The results indicated that the dispersion effect of SAL was better than that of SAL-PEG in preparing hydrophobic dimethomorph SC. While the dispersion effect of SAL-PEG was better than that of SAL in preparing hydrophilic imidacloprid SC. The SC using 2% SAL-PEG had good dispersion effect and can effectively prevent particles growth and coalescence phenomenon of dimethomorph in the process of thermal storage. The suspension rate of imidacloprid SC after thermal storage was still over 95%. In addition, xanthan gum had effect on keeping stability of SC.