Preparation And Properties Of Double Chains Lactosamine Quaternary Ammonium Salts

High petrochemical energy consumption and heavy pollution are common concerns for global economic and social development,and it is imperative to save energy and reduce emissions and achieve the double carbon goal.Therefore,the preparation of surfactants from sugar-based,a renewable resource,is of great significance to promote the green and sustainable development of surfactants.Sugar-based amide quaternary surfactants have both the mildness of sugar-based surfactants and the antibacterial properties of quaternary ammonium salts,and further in-depth research and development of the relevant properties of such products is of great significance at the theoretical level and in application practice.In this thesis,double-chain lactose amide quaternary surfactants were prepared and their physical and chemical properties,application properties and compounding properties were investigated in detail.The main elements are as follows:（1）Novel double-chain lactose amide quaternary surfactants（C_nDDLPB,n=8,10,12,14,16）were synthesized by amidation reactions of lactic acid with alkyl amines to obtain glycosyl amides,followed by quaternization reactions with brominated alkanes of different chain lengths.The chemical structures of the intermediates（DDLPD）and products were also characterized by infrared（FT-IR）,nuclear magnetic resonance hydrogen spectroscopy（¹H-NMR）,nuclear magnetic resonance carbon spectroscopy(¹³C-NMR)and electrospray mass spectrometry（ESI-MS）to determine the structures of the target products.（2）The various physical and chemical properties of the double-chain lactosamine quaternary ammonium salts and their application properties were investigated by static surface tension meter,contact angle meter,conductivity meter and transmission electron microscopy.Among the five surfactants synthesized with different carbon chain lengths,the critical micellar concentration values became smaller with increasing hydrophobic carbon chains and the surface tension increased with increasing carbon chains,among which C₈DDLPB had the strongest ability to reduce the surface tension of water to27.82 m N/m and had high surface activity.Good antistatic properties at hydrophobic chain lengths of 8 and 10;low foam in all products,typical of low foaming products;good bacterial inhibition at hydrophobic chain length 12,with over 95%inhibition of both E.coli and Staphylococcus aureus at a concentration of 350 ppm;The hydrophobic chain lengths of 12 and 14 have good wetting properties for both PTFE and canvas sheets;the hydrophobic chain length of 14 has the best emulsification effect on soybean oil with a water separation time of 16.6 min;the hydrophobic chain lengths of 8 and 14 have good salt resistance to NaCl,CaCl₂and MgSO4,with light transmission rates of over 85%when the salt concentration is 50 g/L.（3）UV characterisation revealed that C₁₀DDLPB had the best compounding stability in the system of double-chain lactosamine quaternary ammonium salt with sodium dodecyl sulphate（K12）.The surface tension,wetting permeability,emulsification,foaminess and aggregation behaviour in the compounded solution were investigated in detail when C₁₀DDLPB and K12were compounded at different mass ratios.When C₁₀DDLPB was compounded with K12 at 1:2,1:1 and 2:1 ratios,theγ_cmcand cmc of the compounded system were lower than those of the single-component system,and the surface activity was improved;the surface tension of the compounded system was the lowest at26.40 m N/m at 2:1 ratio,and the wettability and permeability were the best at this time.When the compounding ratio is 1:5,the system has very good foaming and foam stabilisation,when the compounding ratio is 2:1 and 5:1,the foam is very low,it is a typical low-foaming product,in actual production applications can be formulated in different ratios according to the needs of the sample.