Synthesis Of Comb-like Functional Macromolecule Via Combination Of ROMP And RAFT Living Polymerization And Their Application In Surface Hydrophobic Improvement

Self-assembly is the process of component constructed as a group or structure, self-assembly process enables the disordered state into ordered state. Self-assembling of single macromolecule is superior to that of multi macromolecules in enhancing functionalities due to stability of structure and insensitivity of assembling to concentration. The special structure formed by macromolecular self-assembly plays an important way in enhancing its functionality.In the polymerazation methods, ring-opening metathesis polymerization（ROMP） is a living polymerization in which size and property of side-groups in ring monomers has little effect on polymerization behavior. In macromolecules synthesized by ROMP, unsaturated double bonds are retained and therefore polymer chains have better stiffness. R and Z groups are always retained in the end of the polymer chain, so graft polymerization can be carried out in a continiuous process and the grafting process does not introduce metal ion during RAFT living polymerization. As various living polymerization methods are developed, functional macromolecules of well-defined structure are synthesized and applied to self-assembling. Here, “well-defined” structure includes star, dendrimer and other topologies. The current researches about single chain self-assembly of macromolecules just focus on that of block copolymers and hyper-branched macromolecules. The single chain self-assembly of comb-like macromolecules has little research.In this paper, branched comb-functional polymer was synthesized via combination of ROMP and RAFT polymerization. The main chain of the polymer polymerized via ROMP polymerization, branched chains respectively via the polymerization of 4-vinyl pyridine and tert-butyl acrylate from the RAFT. The self-assembling of single comb-like macromolecules on different substrates and the impact on substrate’s hydrophobic property were explored. The main research contents and results are as follows: 1、First of all, trithiocarbonate chain transfer agent T′ was synthesized and applied to control the homopolymerization behavior of 4-vinylpyridine（4VP）、 tert-butyl acrylate（tBA） and acrylic acid（AA）. Thin layer chromatography（TLC） and 1H NMR analysis were used to confirm the chain transfer agent T′, the yield is 89%. 2、The RAFT living polymerization kinetics of monomer 4VP、 tBA and AA controlled by chain transfer agent T was explored. In the linear increase range of the polymer molecular weight, so the polymerization was terminated after 3h 、3h and 2h respectively. But the separation of PAA is difficult. 3、Chain transfer agent T’ containing norbornene functional groups was synthesized with CH₂Cl₂ as solvent and the 2nd generation Grubbs catalyst through ring-opening metathesis polymerization. The yielded was 80.8% and the degree of polymerization was 104. According to 1H NMR, Mn was calculated as 24529g/mol. 4、Comb-like macromolecule was synthesized with DMF as solvent and V501 as initiator through the RAFT living polymerization of monomer 4VP、 tBA controlled by big macromolecule chain transfer agent T′. In the linear increase range, the polymerization was terminated after three hours. NMR characterization results show that graft ration was 50% and 55.6% respectively, and the average graft length was 306 and 245 respectively. 5、In order to explore the application of polymer’s self-assembly, P4 VP and PtBA were dissolved into 0.001wt% in DMF solution, then different substrates, such as copper, iron, silicon, aluminum foil, glass flakes were dipped in the solution. After evaporation of the solvent, AFM was used to characterize single molecules self-assembled on solid surface. The array morphology was similar to the microstructure of the lotus leaf surface. To test their hydrophobicity application, water droplets were dropped onto the substrate, the dynamic phenomenon was similar as the self-cleaning of lotus leaf surface, then the contact angle of water was measured, the results show that the surface hydrophobic improvement is not only dependent on branched chain composition, but also is affected by substrate materials. Self-assembling of single comb-like macromolecules with improved branches on surface provides a potential feasible method to modify surface hydrophobic property.