丙烯酰胺-甲基丙烯酸共聚物的NMR研究

NMR Studies on AM-MAA Copolymer

用FT-IR光谱,1H-NMR谱,质子弛豫时间等方法研究了在热引发条件下甲基丙烯酸和丙烯酰胺的共聚合反应,讨论了甲基丙烯酸(MAA)、丙烯酰胺(AM)在不同配比,不同反应时间下的共聚合转化率,以及单体配比与聚合物链运动的关系。结果表明,随着甲基丙烯酸(MAA)含量增大,共聚合转化率呈先增大后减小趋势。当AM与MAA物质的量之比为2∶1,热引发共聚合反应时间为3 h,共聚合转化率可达90.2%。从自旋-晶格弛豫时间(T1)和自旋-自旋弛豫时间(T2)的测定得出,当单体配比中MAA含量增加,大分子运动的相关时间(τ)变长,大分子中质子的平均间距变小,链段运动变慢,而高频短程运动则变化不明显。

AM-MAA copolymer have been prepared by treating the aqueous solution of monomers with heat initiators, ^1H-NMR spectra, proton spin-spin relaxation time（T2）, spin- lattice relaxation time（ T1 ） was used to analyze percent conversion and segmental motion. The results indicate that the percent conversion increase, then decrease with the content of MAA increasing. The longer the reaction time was, the larger the percent conversion. From the dates we can know that AM： MAA = 2 ：1（mol/mol） and 3 h is the best reaction condition. The values of T1 and T2 gave us very important information about segmental motion of molecule.