Deuteration-Induced Volume Phase Transition Temperature Shift of PNIPMAM Microgels
Deuteration-Induced Volume Phase Transition Temperature Shift of PNIPMAM Microgels
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DOI：
10.3390/polym11040620
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发表时间：
2019-04-01
期刊：
影响因子：
5
通讯作者：
Hellweg, Thomas
中科院分区：
文献类型：
--
作者：
Cors, Marian;Wiehemeier, Lars;Hellweg, Thomas
通过红外光谱和光子相关光谱（PCS）测定了氘代对聚（N-异丙基甲基丙烯酰胺）（pNIPMAM）微凝胶在水悬浮液中的体积相变（VPT）温度的影响。我们研究了氢化和氘代溶剂（H2O/D2 O），氢化和（部分）氘代单体的效果。氘代单体或与氘代单体的共聚使体积相变温度（VPTT）偏移高达8.4 K至更高的温度，与pNIPAM微凝胶的已知结果良好一致。此外，膨胀曲线的形状被发现取决于氘化，最高的氘化导致最尖锐的VPT。最后，FTIR光谱与PCS之间的定量一致性证明了微凝胶颗粒的空间均匀性。我们的结果是合理化的氘代氢键的影响。对于任何接近VPT的实验测量，包括同位素替代，特别是对比度变化小角中子散射，它们都是至关重要的。
The effect of deuteration on the volume phase transition (VPT) temperature of poly (N-isopropylmethacrylamide) (pNIPMAM) microgels in aqueous suspension is determined via IR spectroscopy and size measurements by photon correlation spectroscopy (PCS). We study the effect of a hydrogenated and a deuterated solvent (H2O/D2O), and of the hydrogenated and (partially) deuterated monomer. Deuteration of the monomer or copolymerization with deuterated monomers shifts the volume phase transition temperature (VPTT) by up to 8.4 K to higher temperatures, in good agreement with known results for pNIPAM microgels. Moreover, the shape of the swelling curve is found to depend on deuteration, with the highest deuteration leading to the sharpest VPT. Finally, the quantitative agreement between FTIR spectroscopy and PCS evidences the spatial homogeneity of the microgel particles. Our results are rationalized in terms of the effect of deuteration on hydrogen bonding. They shall be of primary importance for any experimental measurements close to the VPT involving isotopic substitution, and in particular contrast variation small angle neutron scattering.