Department of Chemistry and Biochemistry, Georgia Institute of Technology, 901, Atlantic Dr., Atlanta, GA 30332, USA.
Carbohydr Polym. 2013 Oct 15;98(1):276-81. doi: 10.1016/j.carbpol.2013.05.081. Epub 2013 Jun 6.
The methyl and hydroxypropyl substituents in hydroxypropyl methylcellulose (HPMC) affect the resulting gel properties. These substituents in five HPMC gels were characterized using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, small-amplitude oscillatory shear measurements, and differential scanning calorimetry (DSC). In FT-IR spectra, the most intense peak appeared at 1053 cm(-1), denoting the presence of the glucose ring. The ratio of peak intensities at 1452 cm(-1), which represents -C-H absorptions, and at 1053 cm(-1) (I1452/I1053) and percent methylation from gas chromatography exhibited a linear association (r(2)=0.6296). The broadening of the Raman spectra indicated that the relative crystallinity of HPMC decreases with increasing hydroxypropyl contents. DSC showed no linear relationship between the percent hydroxypropylation in HPMC and the percentage of free water in an HPMC gel. Small-amplitude oscillatory shear measurements revealed that the formation of an entanglements networks and/or weak gel depends on substituent contents.
羟丙基甲基纤维素（HPMC）中的甲基和羟丙基取代基会影响所得凝胶的性能。使用傅里叶变换红外光谱（FT-IR）、拉曼光谱、小振幅振荡剪切测量和差示扫描量热法（DSC）对五种 HPMC 凝胶中的这些取代基进行了表征。在 FT-IR 光谱中，最强烈的峰出现在 1053 cm(-1)，表示葡萄糖环的存在。代表-C-H 吸收的 1452 cm(-1)处的峰强度与 1053 cm(-1)处的峰强度之比（I1452/I1053）和气相色谱法测定的甲基化百分率呈线性关系（r(2)=0.6296）。拉曼光谱的变宽表明 HPMC 的相对结晶度随羟丙基含量的增加而降低。DSC 显示 HPMC 中的羟丙基百分率与 HPMC 凝胶中游离水的百分比之间没有线性关系。小振幅振荡剪切测量表明，缠结网络和/或弱凝胶的形成取决于取代基含量。
