School of Biosystems and Food Engineering, University College Dublin, Belfield, Ireland.
School of Biosystems and Food Engineering, University College Dublin, Belfield, Ireland.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Apr 5;250:119371. doi: 10.1016/j.saa.2020.119371. Epub 2020 Dec 22.
This work investigates the nature of the molecular interactions between water vapor and polymers using time series Fourier transform infrared (FTIR) spectroscopy. A detailed analysis of the frequency shifts and relative peak intensities led to the conclusion that polyvinyl alcohol (PVOH) sorbed a large quantity of water vapor molecules, resulting in swelling and dissolving of polymer crystallites. Difference spectra were calculated to investigate spectral changes occurring upon sorption by dividing the spectra of polymers during the sorption time series by the spectrum of the dry sample and subsequently subtracting the water vapor spectrum. Based on the absorbance area of the OH stretching vibration region (4000-3000 cm) in difference spectra, the amount of water sorbed was significantly higher in poly-L-lactic acid (PLLA) and polyvinyl chloride (PVC) than in polyethylene (PE) and polytetrafluoroethylene (PTFE), increasing with the hydrophilicity of the surface. The OH stretching band of difference spectra shifted from 3499 cm for PVC, to 3416 cm for PE and finally to 3387 cm for PTFE, indicating a more strengthened hydrogen-bonding network in the PTFE matrix upon water vapor sorption.
本工作使用时间分辨傅里叶变换红外（FTIR）光谱研究水蒸气与聚合物之间分子相互作用的本质。对频率位移和相对峰强度的详细分析得出结论，聚乙烯醇（PVAOH）吸附了大量水蒸气分子，导致聚合物微晶溶胀和解离。通过将吸附过程中聚合物的光谱除以干燥样品的光谱，并随后减去水蒸气光谱，计算差谱以研究吸附过程中发生的光谱变化。基于差谱中 OH 伸缩振动区域（4000-3000 cm）的吸光度面积，在聚 L-乳酸（PLLA）和聚氯乙烯（PVC）中吸附的水量明显高于聚乙烯（PE）和聚四氟乙烯（PTFE），随着表面亲水性的增加而增加。差谱中 OH 伸缩带从 PVC 的 3499 cm 移至 PE 的 3416 cm，最后移至 PTFE 的 3387 cm，表明水蒸气吸附后 PTFE 基质中氢键网络得到了增强。
