物理化学学报
物理化學學報
물이화학학보
ACTA PHYSICO-CHIMICA SINICA
2015年
1期
128-136
,共9页
碱木质素%乙酰化%微结构%聚集%分子量
堿木質素%乙酰化%微結構%聚集%分子量
감목질소%을선화%미결구%취집%분자량
Alkali lignin%Acetylation%Microstructure%Aggregate%Molecular weight
通过对比碱木质素(AL)和乙酰化碱木质素(ACAL)在四氢呋喃(THF)中溶液行为和物理化学性质的差异,揭示了乙酰化处理对碱木质素在THF中微结构的影响。分别采用动态光散射、凝胶渗透色谱(GPC)、透射电子显微镜(TEM)、特性粘度、荧光光谱仪、耗散型石英晶体微天平(QCM-D)和自组装技术等研究了AL和ACAL在聚集形态、聚集机理以及吸附特性等方面的特征。研究发现,乙酰化处理会降低碱木质素在THF中的分子间和分子内聚集程度。 AL在THF中以单分子和聚集体的形式共同存在,分子较为蜷曲; ACAL在THF中则更多地是以单分子形式存在而几乎不存在大聚集体,分子较为伸展,其流体力学半径要比相同绝对分子量的AL更大。 THF中的AL聚集体会在液固界面上发生强烈的吸附,但ACAL由于与溶剂间的相互作用较强而几乎不会吸附在液固界面上。由于AL 分子在THF中较为蜷曲且吸附能力较强,因此利用以THF为流动相的GPC直接测量AL的分子量时所得结果并不准确,为保证GPC的测量结果更加全面可靠,需要在测量前对碱木质素进行乙酰化处理。
通過對比堿木質素(AL)和乙酰化堿木質素(ACAL)在四氫呋喃(THF)中溶液行為和物理化學性質的差異,揭示瞭乙酰化處理對堿木質素在THF中微結構的影響。分彆採用動態光散射、凝膠滲透色譜(GPC)、透射電子顯微鏡(TEM)、特性粘度、熒光光譜儀、耗散型石英晶體微天平(QCM-D)和自組裝技術等研究瞭AL和ACAL在聚集形態、聚集機理以及吸附特性等方麵的特徵。研究髮現,乙酰化處理會降低堿木質素在THF中的分子間和分子內聚集程度。 AL在THF中以單分子和聚集體的形式共同存在,分子較為踡麯; ACAL在THF中則更多地是以單分子形式存在而幾乎不存在大聚集體,分子較為伸展,其流體力學半徑要比相同絕對分子量的AL更大。 THF中的AL聚集體會在液固界麵上髮生彊烈的吸附,但ACAL由于與溶劑間的相互作用較彊而幾乎不會吸附在液固界麵上。由于AL 分子在THF中較為踡麯且吸附能力較彊,因此利用以THF為流動相的GPC直接測量AL的分子量時所得結果併不準確,為保證GPC的測量結果更加全麵可靠,需要在測量前對堿木質素進行乙酰化處理。
통과대비감목질소(AL)화을선화감목질소(ACAL)재사경부남(THF)중용액행위화물이화학성질적차이,게시료을선화처리대감목질소재THF중미결구적영향。분별채용동태광산사、응효삼투색보(GPC)、투사전자현미경(TEM)、특성점도、형광광보의、모산형석영정체미천평(QCM-D)화자조장기술등연구료AL화ACAL재취집형태、취집궤리이급흡부특성등방면적특정。연구발현,을선화처리회강저감목질소재THF중적분자간화분자내취집정도。 AL재THF중이단분자화취집체적형식공동존재,분자교위권곡; ACAL재THF중칙경다지시이단분자형식존재이궤호불존재대취집체,분자교위신전,기류체역학반경요비상동절대분자량적AL경대。 THF중적AL취집체회재액고계면상발생강렬적흡부,단ACAL유우여용제간적상호작용교강이궤호불회흡부재액고계면상。유우AL 분자재THF중교위권곡차흡부능력교강,인차이용이THF위류동상적GPC직접측량AL적분자량시소득결과병불준학,위보증GPC적측량결과경가전면가고,수요재측량전대감목질소진행을선화처리。
The effect of acetylation on the microstructure of alkali lignin (AL) in tetrahydrofuran (THF) was studied. The physicochemical properties of AL and acetylated alkali lignin (ACAL) were compared. Dynamic light scattering, gel penetration chromatography (GPC), transmission electron microscopy (TEM), intrinsic viscosity, fluorescence spectrophotometry, quartz crystal microbalance with dissipation (QCM-D) measurements, and layer-by-layer (LbL) self-assembly were used to investigate the aggregation and adsorption of AL and ACAL. Intermolecular and intramolecular associations in AL decreased fol owing acetylation. AL in THF existed mainly as mono-molecules and intermolecular associations and had a more compact conformation. ACAL existed mainly as mono-molecules with a more stretched conformation. ACAL had a larger hydrodynamic radius than AL (of the same absolute molecular mass), because of its stretched conformation. QCM-D and LbL self-assembly measurements suggested that AL aggregates have a strong tendency to adsorb at the liquid-solid interface, but ACAL hardly adsorb at this interface because of its stronger interaction with THF. The compact conformation and strong adsorption property of AL resulted in inaccurate molecular weights of non-acetylated AL, as measured by GPC with a THF mobile phase. In order to get more reliable molecular weights from GPC measurements, acetylation for AL should be used in the sample pretreatment.