The Synthesis of Two-dimensional Polymers and the Applications in Surface Modification

Author:Li Yang



Degree Year:2019





Two-dimensional(2D)polymers are sheet-like macromolecules consisting of covalently-linked repeating units in a two-dimensional plane.Due to their unique structure of 2D network,2D polymers possess novel properties different from those of 1D and 3D polymers.Thus,2D polymers have attracted a wide range of interest in both basic scientific research and potential impactful technologies.Compared with their 1D and 3D counterparts,the design and synthesis of 2D polymers is more challenging.Various synthetic approaches have been explored towards the preparation of these fascinating sheet-like macromolecules,with the topochemical solid-state polymerization approach being a more successful one to date.Topochemical solid-state polymerization was achieved by in situ topochemical reactions between the monomers in crystalline states,in which the monomers were well aligned.By Topochemical solid-state polymerization approach,2D polymers were constructed with well-characterized periodic structures,large areas and gram-scale yields.However,the prerequisite of crystallinity in the synthesis of 2D polymers continues to hinder the introduction of functional groups,and controlled architectures into 2D polymers.In addition,the challenges in the design,preparation and crystallization of the monomers must be overcome in this approach in order for 2D polymers to be useful for practical purposes.In this work,we exhibited a non-crystallization method towards 2D polymers which can effectively avoid the aforementioned problems.By in situ crosslinking of gemini monomers MA-11-2-11-MA in its bilayer on the solid-lipid interface,2D polymer net-poly(MA-11-2-11-MA)could be constructed with well-controlled size and shape,and diverse functionalities.We proved that 2D polymers can be synthesized from such a dynamic bilayer of gemini monomers and revealed the self-adaptability of gemini monomers and the polymerization-induced structural self-organization affect during the polymerization process by experiment and simulation.Furthermore,the self-adaptability of gemini MA-11-2-11-MA facilitated the access to 2D net-poly(MA-11-2-11-MA)with diverse sizes,shapes,and functionalities by templated polymerization strategy and copolymerization with various functional derivatives.In previous reports,the synthesis of 2D polymers was often carried out on smooth and macro-scale interface,but few examples about the 2D polymerization of monomers were reported on the nanoparticle surface with large curvature.When the surface gets smaller and smaller,the assembly and 2D polymerization of the gemini monomers may be impacted.In this paper,the 2D polymerization of MA-11-2-11-MA on gold nanoparticle surface was studied;the effects of particle size,shapes,surface charge,and ligand replacement efficiency on the 2D polumerization were discussed.As an extension to the synthesis work,we explored the application of the on-surface(co-)polymerization of MA-11-2-11-MA as a surface modification strategy.The cross-linked(co-)polymer can be effectively coated on the surface of macro-scale objects of different materials,and brought surface functionalization and antibacterial properties to the objects.In addition,the(co-)polymer can also be used as a surface modifier for microscopic colloidal nanoparticles,which brought excellent colloid stability,low biotoxicity and functionalized surface for colloidal nanoparticles of different materials,shapes and sizes.It is proved that the on-surface(co-)polymerization of MA-11-2-11-MA is an effective surface modification strategy for both macro-and nanomaterials.