Study On Synthesis And Self-Assembly Behavior Of Water-Soluble Polyamide

Macromolecular self-assembly is one of the important means to construct functionalized micro-nanomaterials.Materials prepared based on macromolecular self-assembly have been proved to have broad application prospects in drug carriers,micro-nano motors,photoelectric materials,micro-electronic devices and other aspects.At present,the research objects of macromolecular self-assembly focus on linear block copolymers and branched block copolymers.In fact,the extensive hydrogen bonding,the easy introduction of functional monomers into the molecule,the alternating linkage of structural units and the super strong crystallinity make polyamide a promising self-assembly building block.However,up to now,there are few reports on self-assembly of polyamide.Based on this,a series of water-soluble polyamides were synthesized and their assemblies were prepared by direct water method.The unique properties and self-assembly mechanism of polyamides were studiedFirstly,amphiphilic polyamide PAGAPs were synthesized from glutaric acid and polyetheramines with different number average molecular weights.The successful synthesis of amphiphilic polyamide was confirmed by FT-IR,~1H-NMR,DSC and TGA.The assembly of amphiphilic polyamide was prepared by direct hydration method.The results of TEM and DLS showed that PAGAP.230 and PAGPA.400 can self-assemble into nanovesicles and nanotubes respectively in 7 days,while PAGAP.2000 can quickly self-assembled into large complex micelles with a particle size of 1.25?m.The results of cryo-electron microscopy,particle size testing,and microthermal DSC indicate that the large complex micelles are formed by secondary aggregation of the primary micelles driven by hydrophobic interaction and hydrogen bonding.In addition,the PAGAP.2000 large complex micelles show a peculiar acid sensitivity,which is summarized as the particle size decreases first and then increases with the increase of acid concentration,and then decreases to complete disintegration.The nature of its acid sensitivity is caused by the combined effects of different concentrations of hydrogen ions on the hydrogen bonds between polyamides and the hydrophilicity of PAGAP.2000 molecules.In order to furtherly explore the self-assembly behavior of polyamides,a highly water-soluble polyamide PASIP.400 was synthesized using sodium isophthalic acid-5-sulfonate and polyetheramine D400 as raw materials.The successful synthesis of the highly water-soluble polyamide was confirmed through FT-IR,~1H-NMR,DSC and TGA.The results of OM,TEM,SEM and AFM proved that PASIP.400 can self-assemble into giant microtubes with a length of millimeters scale and a diameter of2.65?m in aqueous solution.The wall thickness of the microtube increases with the hydration time.It can exceed 250nm after 14 weeks.The PASIP.400 giant microtubes can maintain stable morphology in polar solvents and strong acids,as well as under humid heat(121~oC,1.2atm,1h)and dry heat(200~oC,30min)conditon,exhibiting excellent resistance to chemical solvents and heat.The wide-angle XRD and zeta potential tests show that the polyamide microtube is a densely packed multilayer structure.The results of DSC,FT-IR and TGA prove that multiple hydrogen bonding is the driving force for the self-assembly of PASIP.400,and the reason for its super stability.Water molecules participate in the self-assembly process of PASIP.400.Subsequently,in order to further study the self-assembly characteristics of polyamides,isophthalic acid-5-sodium sulfonate,?,?-dicarboxypolyethylene glycol,metaxylylenediamine,1,12-dodecanedi amine and polyetheramine D2000 were used as raw materials to prepare water-soluble polyamides with different structures.The self-assembly behavior of them in a large-scale time range was tracked and observed using microscopic microscopy technology,and the polyamide containing ether bonds was found showing a common assembly transformation behavior,that is,the transformation process of microtube-microtube containing thin neck-pearl necklace tube-vesicle.In this paper,water-soluble polyamide is used as the precursor,and the molecular structure of polyamide is gradually changed to prepare giant micelles,microtubes and thick-walled vesicle assemblies with unique properties.It provides a new idea for scholars in the field of polymer self-assembly,which has great reference significance.