Synthesis Of Poly Electrolyte Complexes Nanoparticles By Polymerization-Induced Charge Assembly And Their Application

Polyelectrolyte complexes nanomaterials are a kind of functional polymer materials with great protential applications due to their unique properties,such as high charge density,water solubility,biocompatibility and semi-permeability.They are widely used in gene or drug transportation,nanoreactors,ion detection,etc.Controllable and scale-up preparation is essential for the application of polyelectrolyte complexes nanomaterials.In recent years,with the continuous development of polymerization-induced self-assembly technology,polymerization-induced charge assembly has been established for the scale-up preparation of polyelectrolyte complexes nanomaterials.In view of the fact that most studies use polyelectrolyte-neutral diblock copolymers as templates,herein,a new method for preparing complexes nanoparticles is proposed,in which polyelectrolyte homopolymers are applied as templates to induce the polymerization of monomers with opposite charges.On one hand,homopolymer-induced polymerization reduces the synthesis requirements for the template polymers.On the other hand,the cross-linker is copolymerized with the monomer during the polymerization in order to achieve the stable polyelectrolyte complexes nanoparticles.In this paper,the effects of different synthesis factors on the size,structure and stability of the complexes nanoparticles are systematically studied,the synthesis conditions for the scale-uppreparation of complexes nanoparticles are optimized,and their application in the field of nanoreactors is discussed as well.The specific research contents are as follows:(1)With a negatively charged polyacrylic acid(PAA)as template,the polymerization of cationic monomers with different ionization degrees 2-(Dimethylamino)ethyl methacrylate(DMAEMA)and[2-(Methacryloyloxy)ethyl]trimethylammonium chloride(METAC)is investigated.The mixing ratio of the template and monomer is controlled out of the stoichiometry,so the formed polyelectrolyte complexes nanoparticles are stabilized by the excess of the charged blocks.During the polymerization process,N,N'-methylenebisacrylamide(BIS)is introduced as a cross-linker,thereby forming chemical cross-link inside the polyelectrolyte complexes nanoparticles to improve its structural stability.The results show that,for both DMAEMA and METAC reaction systems,the addition of BIS not only reduces the size of polyelectrolyte complexes nanoparticles,but also promotes the monomer conversions.(2)The electrostatic driving force is adjusted by changing the salt concentration during the polymerization.For the two cationic monomers,polymerization was performed at a range of salt concentrations.The results show that the size of polyelectrolyte complexes nanoparticles prepared with different cationic monomers increases linearly with the increasing salt concentration.The size distribution of the nanoaprticles hardly change with increasing salt concentration,demostrating that the size of polyelectrolyte complexes nanoparticles can be tuned by simply adjusting the salt concentration in our synthesis strategy.(3)Our strategy cannot tolerate high monomer concentration due to limited stabilization of the homopolymer system,while the results of volume expansion experiment show that,the reaction runs well with increased volume up to 100x times.Moreover,the polyelectrolyte complexes nanoparticles could be freeze-dried to produce powder product,and the re-dispersion displays show no effect on the particle size and size distribution.Finally,Au@PAA/PDMAEMA nanoparticles is prepared by in-situ reduction and applied to the reduction of p-nitrophenol,showing the potential application as functional nanocarriers.