Xiongfei Zhang,Chuang Ma,Peiyu Liu,Dan Huang,Pengyun Li
Because of its high crosslinking density, compact structure and stable performance, epoxy resin is difficult to be degraded, which leads to serious environmental pollution problems. In this work, using dipropylene glycol dimethyl ether as swelling agent and nitric acid as oxidant, the degradation of amine cured epoxy resin was studied. Results are as follows: The degradation rate obtained by swelling agent assisted oxidation degradation method is much higher than that obtained by oxidation degradation method only. And the degradation rate of the epoxy resin even reached 100 % at 100 °C only in an hour under the condition of swelling agent assisted nitric acid. FT-IR and GC–MS showed that the degradation was mainly caused by that the C N bond in the molecular chain was gradually weakened and fractured finally. The molecular weight of the degradation product was relatively dispersive, which was composed of low molecular polymer and small fragments, and the molecular weight of low molecular polymer was about 2167. And the degradation products primarily contain 4-isopropylphenol and (allyloxy)benzene rings. This work provides a new way to solve the problem about the degradation, recycling and pollution of epoxy resin.
Jiemei Zhou,Xiang Ying,Daiwen Li,Mingjie Wei,Xiangyue Ye,Yong Wang
Nanoporous polymers are extensively coated on various substrates to deliver optical, permselective, or other functions. However, it remains desired to fast produce uniform nanoporous polymer coatings on substrates with complex surfaces. Herein, by manipulating the interactions between block copolymers and selective solvents, we prepare repairable nanoporous polymers on arbitrary substrates. This is realized by an extremely simple sequential coating process: sequential coating of block copolymers and their swelling agents on substrate surfaces. The swelling agents are comprised of two solvents that swell the constituent blocks of the copolymers to different degrees, rapidly producing polymer coatings with uniform, interconnected, sub-50 nm pores. This sequential coating process is able to conformally build nanoporous polymers on nonplanar substrates with large lateral sizes and complex surface features, and also to in situ repair defects arising during usages. We further demonstrate that the nanoporous coatings show excellent antireflective and membrane separation performances. This sequential coating process is dictated by polymer–solvent interactions, and is expected to find applications in diverse fields for its simplicity, adaptability, and the capability to produce well-defined nanoporosities.
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