Research On Polymeric Self-assembly Aggregations As Pseudostationary Phase From Poly (Stearyl Methacrylate-co-methacrylic Acid)

Polymeric micelles self-assembled from poly(stearyl methacrylate-comethacrylic acid)(P(SMA-co-MAA))were used as pseudostationary phase(PSP)in electrokinetic chromatography(EKC),owing to low critical micelle concentration(CMC)and controllable microstructure.The selectivity of PSPs is one key factor of EKC separation performances.One way to improve selectivity of PSP is modification with organic solvents,and it was found that 1-butanol could insert into the polymeric micelle to modify the structure of PSP and improve its selectivity.Furthermore,the alkyl tails on octadecylsilyl(ODS)C18 column in HPLC were similar to that in P(SMA-co-MAA).Thus,it is suitable to compare selectivity between ODS in RP-HPLC and P(SMA-co-MAA)in EKC in the thesis.In typical micellar electrokinetic chromatography(MEKC),addition of organic solvent in the running buffer is a common resolution to separate hydrophobic analytes.So far,organic modifiers have been widely used in EKC.However,to our best knowledge,few researcheres have investigated the influences of the organic solvents on physicochemical and chromatographic characteristics of polymeric micelle as PSP in EKC.Herein,in the thesis,the influences of the organic solvents on the polymeric micelle physicochemical and chromatographic characteristics,and the polymeric PSP modified with organic solvents were compared with C18 column in RP-HPLC with the same organic solvents as mobile phase.Then,the interaction mechanism between analytes and PSP were analyzed by linear solvation energy relationship(LSER)model,and also compared with C18 column in RP-HPLC.At last,the novel micelle PSP was applied for the separation of the hair dyes.The main research contents of the thesis are as follows:1.The influences of the organic solvents on the polymeric micelle physicochemical characteristics including size and microenvironmental polarity were investigated.Furthermore,the polymeric PSP chromatographic parameters such as elution window,hydrophobic selectivity and polar group selectivity influenced by the organic solvents in EKC were also examined in the present work.The results were as follows: Firstly,amphiphilic random copolymer P(SMA-co-MAA)could selfassemble regular spherical micelles,and had extremely low CMC.Secondly,methanol,isopropanol or acetonitrile molecules could not penetrate into the interior of the polymeric micelles,and mainly affected the properties of surrounding running buffer.However,1-butanol molecules could insert into the polymeric micelle and 2% 1-butanol was enough to modify the structure of the micelles.Finally,addition of 2% 1-butanol did not decrease the elution window,instead,improved the hydrophobic selectivity.Furthermore,both better group selectivity and faster migration for relatively hydrophobic analytes could be achieved simultaneously.2.The polymeric PSP modified with organic solvents was compared with C18 stationary phase in RP-HPLC with the same organic solvents as mobile phase.Then,the interaction mechanism between analytes and PSP in EKC,as well as C18 stationary phase in HPLC were analyzed by LSER model.The results were as follows: Firstly,1-butanol as Class I modifier would be beneficial to enhancement of the methylene selectivity of the polymeric PSP and improvement of the retention capacity on hydrophobic analytes.Whereas,methanol and acetonitrile as Class II modifiers decreased the both of them.Secondly,LSER analysis found that hydrophobic interaction and hydrogen bonding acidity were two key factors in polymeric PSP selectivity with or without modifiers,and acetonitrile would weak the hydrogen bonding basicity.Thirdly,compared with C18 column in RP-HPLC,polymeric PSP owned better methylene selectivity and polar group selectivity.Finally,The LSER analysis figured out that polymeric PSP and C18 column owned the same key factors in selectivity,and polymeric PSP owned more diverse selectivity than C18 column.3.Our research group had developed a novel polymeric micelle PSP,self-assembled from P(SMA-co-MAA),to separate 13 kinds of dyes simultaneously.6%(v/v)1-butanol,20%(v/v)methanol and 20 mM Sodium dodecyl benzene sulfate(SDBS)was added in the running buffer to improve the selectivity and efficiency,as well as to shorten analysis time.SDBS and P(SMA-co-MAA)formed mixed micelles,which were used as PSP to realize separatation of 13 kinds of dyes.Thus,the influences of the SDBS on the polymeric micelle physicochemical characteristics including size and surface charge density were investigated simultaneously.The results were as follows: Firstly,with the increases in the concent of SDBS,the size of the polymeric micelles increased and the zeta potential decreased.SDBS molecules could insert into the polymeric micelle to modify the structure of the micelles,and form mixed micelles.It led to increase the polarity interaction between PSP and solutes and improve the selectivity.Secondly,polymeric mixed micelle modified with methanol and 1-butanol as PSP to realize separatation 13 kinds of hair dyes within 18 min.Thirdly,the relative standard deviations of the migration times and peak areas were less than 0.92% and 2.90%,respectively.The linear ranges of the analytes were two orders of magnitude,and the detection limits were ranged from 0.7 to 2.6 mg/L(S/N=3).Finally,the analysis of three real sample of a commercial product of oxidative hair dyes was performed,and the recoveries were between 82.3% and 116%.All the relative standard deviations(RSDs)values are lower than 3%.The method was of simplicity,accuracy and could be applied to the quality control of hair dyes.