Reaction Induced Self-Assembly And Multidimensional Reorganization Of Cystamine-based Reactive Polymer

Reactive polymers represent the development of stimuli-responsive polymer materials, which have wide applications. In complex environment, the multidimensional combination effects between time and space stimulated by the external environment become the essential condition that determines the real applications of reactive polymer materials. It is necessary for us to fundamentally explain the multiple stimuli-responses of reactive polymers and imitate the space-time complexity of protein in order to realize the applications in real life. Besides, in complex aqueous solution, the reactive polymer can secondarily assemble on the initial micelle to realize the building of bottom-up nano hierarchical structure. Therefore, it is needed to prepare environmentally dependent polymers with complete structures by using moderate methods and study their multiple stimuli- responsive assembly behaviors.In this work, reaction induced self-assembly and multidimensional reorganization(RIMDRO) behaviors of a water-soluble reactive polymer of cystamine derivatives are described for the first time and following conclusions are obtained.1. By amidation at low temperatures, we designed and synthesized methacrylamide cystamine derivation functional monomers CysMA, which include highly reactive disulfide bond and ionization primary amine groups.2. Using aqueous RAFT under visible light irradiation at 25 oC, we achieved a controlled polymerization of CysMA monomers. By this polymerization method, we use conventional macromolecular chain transfer agent two-step method to synthesize a block copolymer containing permanently hydrophilic segment; and successfully synthesized full primary amine functional block copolymer by iterative one-pot method. Does not require any separation and purification process, iterative one-pot method can time saving achieved well-defined block copolymer material. At same total feed ratio, by adjusting AEMA and CysMA at different monomer feed ratios, we found that the two monomers are generally ideal random copolymerization, copolymer units statistical distributed in polymer chains. So we got the binary random copolymers and ternary block random copolymers, containing different proportions of ionized primary amine functional group and both highly reactive disulfide and ionization primary amine functional groups on the polymer chains.3. By the titration curve and DLS data of polymers at different pH, we found the pH-liable self-assembly behavior of polymers. Deionization of ionized primary amine group significantly enhanced hydrogen bonding between the polymer structure unit, leading to self-assembly of polymer chains and then phase separation from the aqueous solution. The longer polymers chain length, the more sluggish pH-reliable phase transition behavior.4. 1H NMR results showed that self-assembly of polymer induced the nano-scale confinement of function block at different pH. By the PAEMA67-b-PCysMA98 block copolymers, we got a full primary amine nano-scale aggregates.5. The phase transition can be tuned via statistic incorporation of PAEMA unit into the PCysMA chain to regulate the polymers structure. The hydrogen bond between the structural units of polymers can be regulated. It induced the self-assembly of polymer. So we got nano-scale particles, which include PHPMA/PAEMA permanent hydrophilic shell and PCysMA functional cores including primary amine and highly reactive disulfide bond functional groups.6. We explained the reaction induced self-assembly and multi-dimensional reorganization behavior by 1H NMR and DLS of PHPMA90-b-PCysMA84 at different pH from acidic to alkali water. We found that reaction of reduction of disulfide bond and thiol/primary coordination of polymers was diversity at different solution pH. These selective reactions play vitally crucial roles in control over phase transition thus self-/co-assembly. Both endow the reactive polymer with complexity and diversification in the interactions and thus the vast reorganizations. The intriguing reorganization diversification is thus termed as Reaction Induced Multidimensional Reorganization(RIMDRO).7. Meanwhile, reorganizations are strongly liable to CysMA/AEMA ratio and solution pH. DLS data of PHPMA90-b-P(AEMA16-stat-CysMA78) and PHPMA90-b-P(AEMA77-stat-CysMA18) proved that CysMA/AEMA monomer ratio in polymer structure and the solution pH can effectively regulated the RIMDRO behavior.The structure-tunable reaction induced RIMDRO holds potentials toward chemistry within media-liable and nano-confined environment that exists extensively within proteins.