Study On Synthesis And Properties Of Oligomeric Surfactants Based On Adamantane

Oligomeric surfactants are a novel family of amphiphilic compounds made up of two or more conventional surfactant "monomers" linked by spacer group(s) at the level of, or very close to the head groups. Since the hydrophobic chain will be closer and more regular than conventional surfactants, oligomeric surfactants have powerful surface activity. The diameter of adamantane molecular is 0.74 nm, which is smaller than the equilibrium distance of conventional surfactants, the properties of adamantane, such as non-toxic, sublimation, high thermal stability and resistance to oxidation, the oligomeric surfactants used adamantane as spacer may possess some excellent performance. In this thesis, the design, synthesis and properties of some degradable oligomeric surfactants based on adamantane are studied. Furthermore, some mechanisms of some key reactions were discussed, the reaction condition were optimized. All of the key intermediates and surfactants were characterized by IR,1H NMR and elemental analysis.(1) Some key intermediates,1,3-adamantanedicarboxylic acid, 1,3-di am ino adamantane, N, N,N’,N’-tetramethy 1-1,3-bis(amino methyl)-adamantane, 1,3-bis(chloromethyl)adamantane, were synthesized for the purpose of produce oligomeric surfactants. Under the optimum condition, the (total) yield of 1,3-adamantanedicarboxylic acid,1,3-diaminoadamantane, N,N,N’,N’-tetramethyl-1,3-bis(aminomethyl)adamantane, 1,3-bis(chloro-methyl)-adamantane were 92%,72%,81%,27.1%.(2) An tetra sulfate substitute-adamantane surfactants,1,3,5,7-tetrakis (4-sodium sulfate phenyl) adamantane, was designed and synthesized from adamantane, benzene and chlorosulfonic acid. The CMC value andγcmc of this surfactant were 0.3 mM and 48.7 mN/m, respectively. This compound is an efficient halogen-free flame retardant also. (3) A series of adamantane based degradable oligomeric (trimeric and tetrameric) quaternary ammonium surfactants were synthesized from adamantane, chromium trioxide, bromoacetyl bromide and tertiary amine. The oxidation reaction was optimized. Under the optimum conditions, the yields of 1,3,5-trihydroxyadamantane and 1,3,5,7-tetrahydroxy-adamantane were 50.1%and 41.7%, respectively. The yields of esterification and quaterisation reaction were more than 80%. The mechanisms of oxidation and esterification reaction were discussed.(4) Surface tension data which had been achieved by ring-method, showed that the oligomeric surfactants had strong surface activity, the CMC values andγcmc of the oligomeric surfactants reached 0.50 mM and 37.20 mN cm-1, respectively. The CMC values were tested by conductivity and fluorescence method, the results had paralleled with the surface tension method. The CMC values andγcmc of these surfactants are less affected by NaBr. C20,Γm, amin, micro-polarity (ε), micelle aggregation number (N) and micelle ionizability (β) of surfactants was reported. Influences of length of hydrophobic chain and oligomerization degree on the properties of surfactants were investigated, the results shown that longer chain had better performance (The carbon atoms of hydrophobic chains was between 8-12); trimeric surfactants had smaller CMC values than tetrameric surfactants, theγcmc and C20 of tetrameric surfactants were lower than trimeric surfactants.(5) The foam properties, solubilization and emulsification of the surfactants were investigated. It showed that, surfactants had good to excellent foaming property; the Kmc (mole fraction micelle-phase /aqueous-phase partition coefficient) was tremendous, the negative free energy of transfer indicated the process of solubilizates transfered from the aqueous phase into the micellar pseudophase was favorable and spontaneous; the emulsification properties of these surfactants were better than the conventional and Gemini surfactants which had same hydrophobic chain.