回转半径
化学
特性粘度
壳聚糖
持续时间
水溶液
静态光散射
水动力半径
维里系数
聚合度
高分子化学
结晶学
位阻效应
聚合
立体化学
动态光散射
聚合物
物理化学
热力学
有机化学
材料科学
胶束
纳米技术
物理
纳米颗粒
作者
Guillaume Lamarque,Jean-Michel Lucas,Christophe Viton,Alain Domard
出处
期刊:Biomacromolecules
[American Chemical Society]
日期:2005-01-01
卷期号:6 (1): 131-142
被引量:167
摘要
Physicochemical properties of four different homogeneous series of chitosans with degrees of acetylation (DA) and weight-average degrees of polymerization (DP(w)) ranging from 0 to 70% and 650 to 2600, respectively, were characterized in an ammonium acetate buffer (pH 4.5). Then, the intrinsic viscosity ([eta](0)), the root-mean-square z-average of the gyration radius (R(G,z)), and the second virial coefficient (A(2)) were studied by viscometry and static light scattering. The conformation of chitosan, according to DA and DP(w), was highlighted through the variations of alpha and nu parameters, deduced from the scale laws [eta](0) = K(w)and R(G,z) = K', respectively, and the total persistence length (L(p,tot)). In relation with the different behaviors of chitosan in solution, the conformation varied according to two distinct domains versus DA with a transition range in between. Then, (i) for DA < 25%, chitosan exhibited a flexible conformation; (ii) a transition domain for 25 < DA < 50%, where the chitosan conformation became slightly stiffer and, (iii) for DA > 50%, on increasing DP(w) and DA, the participation of the excluded volume effect became preponderant and counterbalanced the depletion of the chains by steric effects and long-distance interactions. It was also highlighted that below and beyond a critical DP(w,c) (ranging from 1 300 to 1 800 for DAs from 70 to 0%, respectively) the flexibility of chitosan chains markedly increased then decreased (for DA > 50%) or became more or less constant (DA < 50%). All the conformations of chitosan with regards to DA and DP(w) were described in terms of short-distance interactions and excluded volume effect.
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