Structure-Property Relationships Of Extended Surfactants Depending On Polyether Spacers

Extended surfactants（e-surfactants）were synthesized by inserting a propoxy-containing polyether spacer between the hydrophobic alkyl chain and the hydrophilic head group of a conventional surfactant molecular.E-surfactants exhibit many excellent physical and chemical properties.What is the structure-property relationships e-surfactant containing copolyether spacer?Does the biphasic affinity of the PPO spacer make the e-surfactant molecule responsive to stimulation?At the same time,e-surfactant can be used as a laundry detergent?To solve the above problems,we studied the contributions of different spacers and the synergistic effect between the spacers and the hydrophilic head group to the properties of e-surfactants from the structure of the polyether spacers.First,three series of sulfate e-surfactants containing PPO-b-PEO spacer,PEO-b-PPO spacer and PPO-co-PEO spacer were designed and synthesized,to explore the synergistic effects of different PPO and PEO spacer connections on their surface chemical properties and application properties.Secondly,three kinds of carboxylate e-surfactants containing PPO spacer were designed and synthesized.The synergistic effects of PPO spacers and carboxylic acid on their CMT and CP properties were studied,and the salt effect and pH effect of multi-sensitivity reversible phase behavior were explored.Finally,twelve kinds of sulfate e-surfactants with PPO spacers were designed and synthesized,and their properties and application properties as laundry detergents related to low-temperature washing and soil removal of fabrics were studied.Besides,their properties that meet the development trend of detergents such as easy to rinse,low residue and low irritation were also explored.The main results and conclusions are as follows:（1）Twenty-one kinds of sulfated e-surfactants containing only PPO spacer or copolyether spacer were synthesized from fatty alcohol by alkoxylation,sulfation and neutralization.Three kinds of carboxylate e-surfactants containing only PPO spacer were synthesized from 1-bromooctadecane through Williamson condensation,carboxymethylation and neutralization.The identity of the synthesized product was confirmed by FT IR,ESI-MS and ¹H NMR.（2）Based on the Gibbs isothermal equation of the surface tension curve of e-surfactant and the insoluble monolayer experiments of intermediates,it was confirmed that the three series of sodium lauryl copolyether sulfate e-surfactants(C₁₂（P_p-b-E₃）S、C₁₂（E₃-b-P_p）S and C₁₂（P_p-co-E₃）S)exhibited the rugby ball shape at the interface,all of which were induced by the molecular collapse at the interface due to the PPO and PEO spacer in the molecule. Affected by the structure of copolyether spacers,the molecular surface adsorption areas of C₁₂（P_p-b-E₃）S、C₁₂（E₃-b-P_p）S and C₁₂（P_p-co-E₃）S increased in sequence,and the areas in each series increased with the increase of p value.When p=9,the molecular surface adsorption area of e-surfactant was 142（?）²,188（?）² and 222（?）²,respectively.In addition, the larger the molecular surface adsorption area of the e-surfactant,the better the electrolyte tolerance,the calcium soap dispersibility,and the low foamability.For C₁₂（P₉-co-E₃）S,the calcium ion tolerance was 173 g/L,the lime soap dispersing power was 86.1 mol/mol,and the foamability was 18.5 m L.Therefore,these three series of e-surfactants are expected to be applied to low-foaming anionic surfactants,high-efficiency emulsifiers,strong anti-electrolyte（calcium ion tolerance）surfactants and high-efficiency lime soap dispersants.（3）With the combination of PPO spacers and carboxylate groups,the solution of carboxylate e-surfactants(C₁₈P_pC)appears cloudy-clear-cloudy temperature-sensitive reversible phase transition behavior in the process of multiple heating-cooling cycles,and the corresponding CMT or CP respectively.With the increase of p value in the molecule,the CMT decreases and CP increases of C₁₈P_pC,and the dual-critical temperature range corresponding to the dissolution interval becomes wider.With the increase of salinity and pH,the dual-critical temperature range becomes narrow of C₁₈P_pC.The CMT=38℃and the CP=75℃of the 1.0 wt.%C₁₈P₃C aqueous solution,when the salinity is 3.0 wt.%and the pH is 8.5.For the same solution,the viscosity of the solution increased significantly when the CMT was reached.Between CMT and CP,the viscosity of the aqueous C₁₈P₃C solution decreased gradually with the increase of temperature.At the shear rate of 10^-3～10^-2 s^-1,the solution achieved a high viscosity within a certain temperature range,which was close to or even more than 20 Pa s.Therefore,C₁₈P_pC is expected to be applied to temperature-stimulated,salinity-stimulated and pH-stimulated multi-sensitivity reversible phase change surfactants, and also expected to be used in an environment requiring high viscosity within a certain temperature range.（4）Using sodium lauryl polyoxyethylene ether sulfate(C₁₂P₃S)instead of SLE₃S and LAS in standard laundry detergent,its detergency to carbon black（JB-01）and sebum（JB-03）at 5～10℃is significantly better than that of standard laundry detergent,so it can be recommended as the main surfactant in toiletries suitable for low temperature washing.In addition,the formula using sodium hexadecyl polyoxypropylene ether sulfate(C₁₆P_pS) instead of SLE₃S and LAS in standard laundry detergent has better detergency to JB-03 in the range of 10～30℃,and has the advantages of easy rinsing,low residual rate and low irritation,so it can be recommended as the main surfactant in low-foam inner laundry detergent.（5）The research in this paper has theoretical significance and application value for designing and developing new high-efficiency multifunctional surfactants and their formulations.