Synthesis Of Block Polymers With PDMAEMA By ATRP And Study On Their CO₂ Responses

With the greenhouse effect on the environment increasing, people want to find a new way to reduce carbon dioxide which is the main factors of greenhouse effect. Carbon dioxide is a chemical substance which is very stable. It raises the problems on how to deal with carbon dioxide. Meanwhile, kinds of stimulus polymers were developed. But peoples found that those smart polymers had various problems. In this condition, CO2 stimulus appeared. Carbon dioxide response is quite different from the previous pH, thermal response, which essentially has unique advantages. Mai-n stimulus of CO2 response is carbon dioxide, which can change internal structur-es, macroscopic properties of the system. As the stimulation source, gas carbon dioxide stability is very good, at the same time, the general response of carbon dioxide are reversible, In this article, two kinds of block polymers were synthnized by atom transfer radical polymerization (ATRP) with methylamino ethylmethacrylate (DMAEMA) as the CO2 response uints. And polyethylene glycol and polystrene were chosed as hydrophobic and hydrophilic segment. We also studied on the CO2 response of block copolymer and their potential applications.1. CO2 responsive polymer polystyrene-block-poly (2-(dimethylamino) ethyl methacrylate) PS-b-PDMAEMA was synthesized by ATRP. CO2 response was confirmed by the conductivity test. While a special reaction was found that PS-PDMAEMA could react with dodecyl sulfate sodium salt (SDS) under CO2 at room temperature, this reaction was confirmed by NMR, IR, and TGA. The reaction product had stronger crystallization behavior, which was confirmed by TEM, and DSC. SDS is grafted with the protonated tertiary amines induced to the length increase of side chain. The long side chain could arrange regularly and resulted in the improvement of the crystallization performance.2. Triblock polymer PDMAEMA-PEO-PDMAEMA was synthesized by Atom transfer radical polymerization (ATRP). CO2 response was confirmed by the conductivity test and NMR. Then thisl polymer was added into the system of laponite, PF127 and water. The system exhibits a strong response to CO2, changing from a low viscous solution to a strong viscoelastic gel. In the presence of CO2, the DMAEMA units are protonated and the positive charged triblock copolymer bridged the negative charged nanocalys, formation of a physical network. As a consequence, a sol to gel transition is observed at the macro level. Upon removal of CO2 through bubbling with N2, a corresponding gel to sol transition occurs due to the deconstruction of the physical network, which is a result of the departure of the deprotonated PDMAEMA blocks from the nanocalys. This sol to gel transition is fully reversible. Besides, we have successfully demonstrated the viscoelastic gel possess excellent self-healing and delay ability.