RAFT Polymerization Of DAAM And The Post-polymerization Modification

With a span as long as the history of polymer science itself,post-polymerization modification represents a versatile platform for the preparation of diversely functionalized polymers from a single precursor.Diacetone acrylamide(DAAM) is an important vinyl monomer which played an important role in the chemical industy, and has been used in various fields involving coatings, adhesives, photosensitive resin additives, medical materials. Polydiacetone acrylamide(PDAAM),having reactive keto carbonyl groups pendant to the polymer backbone, is very suitable to prepare reactive and functional polymers through post-polymerization modification. The polymerization of DAAM has been reported by conventional free-radical polymerization and ionic polymerization. While, PDAAM synthesized by conventional radical polymerization lacks accurate structural control due to the nonliving nature of the polymerization technique, while well-defined polymer architectures are required for many applications of the reactive polymers.Meanwhile, the stringent polymerization conditions of ionic polymerization significantly restrict the applicability of this synthetic route. Throughout the past decade, living radical polymerization(LRP)has become one of the most powerful synthetic tools for the preparation of well-defined polymers. While, the polymerization of DAAM through LRP method has rarely reported.In this article, PDAAM was synthesized via reversible addition-fragmentation chain transfer(RAFT) polymerization. Kinetic studies indicated a well-controlled behavior of this RAFT polymerization.The characteristics of this RAFT polymerization was also confirmed by a well-controlled chain-extending RAFT polymerization using the above-synthesized PDAAM as a macromolecular chain transfer agent.Base-catalyzed aldol condensation of PDAAM with benzaldehyde was also used to obtain poly[N-(1,1-Dimethyl-3-oxo-5-phenyl-pent-4-enyl)-acrylamide](PDMOPPEAM) having cinnamoyl groups, and the photoreactivity of polymer with cinnamoyl group was studied by UV-visible and IR absorption spectroscopy. Also, the PDMOPPEAM-b-PNIPAM was synthesized via aldol condensation, and the photoreactivity of the copolymer with cinnamoyl group was studied by UV-visible and IR absorption spectroscopy. Moreover, the micelles of the copolymer could be effectively stabilized in DMF on irradiating for180 min.Acid-catalyzed ketalization of PDAAM with trimethylol propane(TMP) was carried out to obtain the polymer containing pendant cyclic ketal groups and hydroxyl groups, PDAAM-TMP. PCL was grafted from PDAAM-TMP by ring-opening polymerization(ROP) in the presence of tin 2-ethylhexanoate as catalyst to obtain cylindrical polymer brushes.And both of these two polymers prepared from PDAAM werecharacterized by FT-IR and 1H NMR spectroscopy.