| With the rapid development of public transportation in our country,the requirements for the emulsified asphalt technology are increasing.Cationic surfactants,as an essential part in this field,were widely applied as the asphalt emulsifiers.Their exhibited advantages have attracted much attention from this area.However,for the domestic cationic surfactants,they are commonly characterized by slow replacement,low quality as well as being critical to be used,which significantly limited their industrial applications.To investigate their application performance as the asphalt emulsifiers,in the present study,a series of phenylenediamine cationic gemini surfactants as well as N-alkyl bis-quaternary ammonium salt surfactants have been developed.Moreover,systematic experiments were performed to study their surface?interface?chemistry properties,emulsibility,foamability and antimicrobial properties.The main contents and conclusions are shown below:A category of phenylenediamine cationic asphalt emulsifiers(C12,C16 and C18)were synthesized by using p-phenylenediamine,N,N-dimethylalkyl amines(alkyl length=C12,C16and C18),hydrochloric acid,and epichlorohydrin as raw materials via a two-step manner.Single-factor experiments were performed to optimize the involved ucleophilic substitution reaction?second step?.The optimum operational parameters were:n?p-phenylenediamine?:n?N-?3-chloro-2-hydroxy?propyl-N,N-dimethylalkylammonium chloride?=1:2.2,n?sodium carbonate?:n?p-phenylenediamine?=2:1,with a reaction temperature of 85? and a reaction time of 30 h.In this case the yields of C12,C16 and C18 were 76.8%,77.5%and 77.4%,respectively.The obtained products were characterized by IR,MS and 1H NMR.The Krafft points of C12 and C16 were below 0?,while the Krafft point of C18 was 10.3?.The surface tensions of C12,C16 and C18 at different temperatures were determined.Results showed that at298 K,the cmc of C12,C16 and C18 were 3.29×10-3 mol?L-1,2.53×10-4 mol?L-1,and 3.14×10-4mol?L-1;the?cmc of C12,C16 and C18 were 28.24 mN?m-1,31.95 mN?m-1,and 35.06 mN?m-1;the degree of counterion binding?K0?of C12,C16 and C18 were 0.6282,0.6413,and 0.6432,respectively.The cmc increased gradually with the increasing temperature,while the?cmc and K0 decreased slightly.Thermodynamic functions showed that the micellization was an exothermic and spontaneous process.The order to reduce the paraffin-water interfacial tension capability was:C12<C16<C18.In addition,the growth of the alkyl chain reduced foaming ability.C12,C16 and C18 could increase the antibacterial rate of Candida albicans and Staphylococcus aureus to 99%after 2 min,and increased the inhibition rate of E.coli to99.99%after 20 min.A category of N-alkyl bis-quaternary ammonium salt surfactants?HPDDC,HPTDC and HPHDC?were synthesized by the usage of N,N-dimethylalkyl amines(alkyl length=C12,C14 and C16),trimethylamine hydrochloride,and epichlorohydrin as raw materials in two steps.The quaternization reaction?the second step?was optimized via orthogonal experiments.When n?3-chloro-2-hydroxypropyltrimethylammonium chloride?:n?N,N-dimethylalkyl tertiary amine?=1.1:1,the reaction time was 6 h,the reaction temperature was 80?,the yields of HPDDC,HPTDC and HPHDC were 85.8%,86.4%and 85.4%,respectively.The obtained products were verified by IR,MS and 1H NMR.The Krafft points of HPDDC,HPTDC and HPHDC were all below 0?;The cmc of HPDDC,HPTDC,and HPHDC were7.35×10-3 mol?L-1,4.67×10-3 mol?L-1 and 3.08×10-3 mol?L-1;the?cmc of HPDDC,HPTDC and HPHDC were 32.93 mN·m-1,33.85 mN·m-1 and 35.05 mN·m-1;The degree of counterion binding?K0?of HPDDC,HPTDC,and HPHDC were 0.3574,0.3920 and 0.4390,at 298 K,respectively.Similarly,as the temperature raised,the cmc increased gradually,but the?cmc and K0 decreased moderately.By calculating the thermodynamic functions,it was shown that the micellization process was exothermic and spontaneous,with the capability to reduce the paraffin-water interfacial tension in ranking:HPDDC<HPTDC<HPHDC.The order of foam height at 0 min was HPHDC>HPTDC>HPDDC.Furthermore,by testing the antibacterial performance,it is indicated that HPDDC,HPTDC and HPHDC could increase the antibacterial rate of Candida albicans and Staphylococcus aureus to 99%after 2 min,and increase the inhibition rate of E.coli to 98%after 10 min.The relevant properties of the synthesized cationic asphalt emulsifiers for the emulsifier asphalt application were determined.Results showed that the phenylenediamine emulsified asphalt had good stability.The mixing time was more than 120 s,and the demulsification time was around 20 minutes.All of them were slow-cracking and quick-setting asphalt emulsifiers.The stability of N-alkyl diquaternary ammonium emulsifier asphalt has reached the relevant standards.The mixing time was more than 120 s,and the demulsification time was more than30 minutes,indicating that the series emulsifiers were slow-set asphalt emulsifier. |
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