Synthesis Of Linear Hydroxyl-terminated Hyperbranched Polymers,Phosphorylation And Application To Fatliquoring Functions For Leather Procession

Hyperbranched polymers are torispherical irregular macromolecules with highly branched architecture,large number of terminal functional groups,showing high solubility and chemical reactivity.In recent years,the synthesis and characterization methods have tended to mature,so investigations on the modification of hyperbranched polymers to obtain various functional materials have become a new research direction.The PAMAM contains a large number of active hydroxyl groups,which could be functionalized.In this study,the linear-hyperbranched phosphate esters were constructed through random multibranching esterification of lauroyl chloride to PAMAM and the phosphate ester as a branching agent.Subsequently,the products were applied in the leather-making as the fatliquor.The interaction mechanism between branched molecular and collagen fibers of the leather was also demonstrated.Firstly,the PAMAM-n were obtained by the esterification of PAMAM with lauroyl chloride in N,N-Dimethylformamide(DMF).Triethylamine was added as the acceptor of HCl.The reaction between lauroyl chloride and PAMAM was in different molar ratios.The structures of PAMAM-n were characterized by FT-IR,1H NMR and the value of hydroxyl.It was found that the surface tensions basically lied in 21.38~27.96 mN·m-1,the average particle sizes of the PAMAM-n were 120.6~457.8 nm and the PAMAM-3 exhibited the excellent surface activity.Next,on the premise of the above reaction,PAMAM-3-P was prepared by the phosphorylation of PAMAM-3 using P2O5 as a reactant and CCl4 as dispersing agent in tetrahydrofuran(THF).Meanwhile,the product was hydrolyzed,and the reference index was phosphate monoester and phosphate diester.The optimum synthesis condition was: the mole ratio of P2O5 to CCl4 was 1:2.5,the esterification temperature was 60?,the esterification time was 6 h,the hydrolysis temperature was 65?,and the hydrolysis time was 3.5 h.The structure of PAMAM-3-P was characterized by FT-IR,1H NMR,13 C NMR and GPC.What`s more,the polymer showed the low critical micelle concentration(CMC)measured by surface tension-concentration plots measurement and steady-state fluorescence measurement.Meanwhile,the emulsion had good stability and the particle size was measured to be 180 nm by DLS.Then,the fatliquor was synthesized by the castor oil and mixed systems,and the properties of mixed systems of a linear-hyperbranched phosphate salt and a nonionic surfactant(AEO-9)were also studied.The mixed condition was optimized by the single-factor experiments when the HLB was 10.5,the temperature was 60?,the time was 60 min,the stirring rate was 500 r·min-1,the p H was 7,and the mole ratio of compound and grease is 3:0.75.Next,the surface tension,CMC,particle size,and stability were studied.The result demonstrated that the product showed good emulsion stability and the surface tension was 30.67 mN·m-1,the CMC was 0.28 g·L-1,and the particle size was 203.2 nm.Finally,PAMAM-3,PAMAM-3-P and the compound were applied in the leather fatliquoring process,using the sheep garment leather of blue-wet as the materials.The micro structure of leather treated with PAMAM and PAMAM-3-P were analyzed by SEM,XPS,XRD,TG and so on.It was shown that the products with three dimensional structures could be filled in the interfibrillar regions within leather.Meanwhile,the binding of products to collagen fibers led to the decrease in the structural order and enlarge the interfibrillar distance.However,the addition of PAMAM or PAMAM-3-P did not destroy the triple helices of collagen.Finally,the physical and mechanical properties,softness,and thickening rate of the leather were characterized by tensile machine,softness measurement instrument,and thickening apparatus.It was found that the softness and the thickening rate could be greatly improved after the leather was treated with the compound.In addition,PAMAM-3 and PAMAM-3-P could greatly improve the tensile and tear strength of leather.The above results clearly showed that the linear hyperbranched polymers and the linear-hyperbranched amphiphilic phosphate esters can be probably used as an excellent fatliquoring agent.