影响NIPAAm原子转移自由基聚合因素的探讨

Effect Parameters in Atom Transfer Radical Polymerization of N-Isopropylacrylamide

分别以H2O、i-PrOH、二甲亚砜(DMSO)和N,N-二甲基甲酰胺(DMF)与H2O的混合溶剂为反应介质,氯化亚铜(CuCl)、溴化亚铜(CuBr)为催化剂,α-溴代丙酸乙酯(EPN-Br)、α-氯代丙酸乙酯(ECP)为引发剂,N,N,N′,N″,N″-五甲基二亚乙基三胺(PMDETA)、三-(2-二甲氨基乙基)胺(Me6TREN)为配体,使N-异丙基丙烯酰胺(NIPAAm)进行原子转移自由基聚合(ATRP),考察了催化剂、配体、引发剂、溶剂类型对ATRP反应的影响。相关测定表明,在40℃,以i-PrOH为反应介质,保持ECP∶CuCl∶Me6TREN=1∶1∶2,可得到分子量分布窄、分子量可控的PNIPAAm,说明其聚合过程符合ATRP反应的特征。

Poly（N-isopropylacrylamide） （PNIPAAm） was synthesized by atom transfer radical polymerization （ATRP） using ethyl-2-chloropropionate （ECP） or ethyl-2-bromopropionate （EPN-Br） as initiator,CuCl or CuBr as catalyst,N,N,N′,N″,N″-pentamethyl diethylenetriamine （PMDETA） or tris[2-（dimethylamino）ethyl]amine （Me6TREN） as ligand in different solvents （2-propanol,dimethyl sulfoxide （DMSO）,H2O,VDMF/VH2O=1∶1,VDMF/VH2O=1∶2）. The effects of catalyst,ligand,initiator,solvent types on ATRP reaction were discussed. Structure and number-average molecular weight of the PNIPAAm were characterized by means of nuclear magnetic resonance （^1H-NMR） and gel permeation chromatography （GPC）. It is found that the molecular weight distribution of the resulted PNIPAAm is low in 2-propanol at 40 ℃ under n[ECP]∶n[CuCl]∶n[Me6TREN]=1∶1∶2 condition. The low critical solution temperature （LCST） of PNIPAAm is dramatic decrease with increasing number-average molecular weight.