Zhihai Hao

Sweet potato starch residue as starting material to prepare polyacrylonitrile adsorbent via SI-SET-LRP.

Sweet potato starch residue (SPSR) was used as starting material to prepare an eco-friendly adsorbent. SPSR was modified by bromoacetyl bromide to obtain a macroinitiator for surface-initiated single electron transfer-living radical polymerization (SI-SET-LRP) of acrylonitrile (AN) catalyzed by La(0)/hexamethylenetetramine (HMTA) in N,N-dimethylformamide (DMF) in the presence of ascorbic acid (VC). The amidoxime (AO) adsorbent was prepared by the reaction of the graft copolymer bromoactylated sweet potato starch (BSPS)/polyacrylonitrile (BSPS-g-PAN) with hydroxylamine. The maximum adsorption capacity for Hg(II) was 4.03 mmol·g(-1). This simple method provided a novel approach to recycle and reuse agricultural residues for controlling heavy metal pollution.

Reverse Atom Transfer Radical Polymerization of Acrylonitrile Catalyzed by FeCl3/Lactic Acid

Reverse atom transfer radical polymerization (RATRP) of acrylonitrile (AN) was carried out using azobisisobutyronitrile (AIBN) as initiator, ferric trichloride anhydrous (FeCl3)/lactic acid (LA) as catalyst system; a ratio of FeCl3/LA was 1:2 gave the best control. RATRP of AN with N,N-dimethylformamide (DMF) as solvent gave the moderate polymerization rate and the narrowest polydispersity index (PDI). When FeCl3 was replaced by CuBr2, RATRP of AN showed a longer induction period. When Cu was added to the CuBr2-based catalyst system, the induction period was reduced. 1H-NMR spectra of PAN verified the possibility of controlled/living polymerization for future chain extension.

Reverse ATRP of Methacrylonitrile with Diethyl 2,3-Dicyano-2,3-Diphenyl Succinate/SmCl3/Lactic Acid

Diethyl 2, 3-dicyano-2, 3-diphenyl succinate (DCDPS) was applied to initiate reverse atom transfer radical polymerization of methacrylonitrile (MAN) in N,N-dimethylformamide (DMF) with SmCl3 and lactic acid (LA) as catalyst and ligand for the first time. The polymerization proceeded in a well-controlled manner as evidenced by kinetic studies. Compared with reverse atom transfer radical polymerization initiated by AIBN, the polymerization initiated by DCDPS not only showed better control of molecular weight, but also provided narrower molecular weight distribution. The slow polymerization rate and the broad polydispersity index were observed using cyclohexanone and toluene instead of DMF as reaction media. There was no apparent variation of the polymerization rate and polydispersity with initial monomer concentration. The block copolymer PMAN-b-PSt was obtained via a conventional ATRP process by using the resulting poly(methacrylonitrile) as macroinitiator.