The Relationship between Intrinsic Viscosity and Algebra of Dendritic Polymers

Xu Min i*2 Yan Xiaohu1 Cheng Shi1 Yu Xuehai (College of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093) (2 Analysis and Test Center, East China Normal University, Shanghai 200062) Intrinsic relationship between intrinsic viscosity and algebra of dendrimer, analysis The intrinsic cause of the intrinsic viscosity-specific behavior of dendrimers makes it possible to predict the intrinsic viscosity of dendrimers.

Dendrimers are a hotspot in polymer research in recent years. They have a highly regular molecular structure, close to functional groups on the sphere surface, and a large number of cavities in the interior. These special structures lead to many of their properties and linearity. There are big differences in the molecules. Solution properties are one of the basic properties of polymers, and intrinsic viscosity is an important parameter of dendrimers. Therefore, people have conducted many studies on the solution properties of dendrimers, and found that the nature of the dendrimer solution One of the biggest differences with conventional linear polymers is their intrinsic viscosity. Relative to linear polymers with the same molecular weight, dendrimers have lower intrinsic viscosity, the absolute value is generally below 10; and g is not equal to lgM. The linear relationship 1341 was observed. The intrinsic viscosity of the sample increased with the addition of algebra and then increased. It can be expected that with the addition of algebra, the closeness of the molecule increases, and the final intrinsic viscosity should tend to be a limiting value that does not change with changes in molecular weight. Crosby15 has reported that the intrinsic viscosity of each generation of lysine-based dendrimer is 0.025dL/g. These phenomena originate from the unique structure of the dendrimer, and there is no mature theory to explain it. Lescanec 161 and Mansfiled 171 tried to simulate the growth of a dendrimer and gave the upper and lower limits of the intrinsic viscosity, but the reasons for this are still not clear. We also studied the solution properties of dendrimers and hyperbranched polymers, and qualitatively described the specific behavior of intrinsic viscosity of dendrimers from the point of view of the flow model. 18. We believe that dendrimers are algebraic. Addition, the flow pattern in the solution will change from the "through-flow model" to the "no flow-through model", and this change has an important effect on the behavior of the intrinsic viscosity. However, there is no quantitative formula for calculating the intrinsic viscosity of a dendrimer solution. The purpose of this paper is to discuss the relationship between the intrinsic viscosity of a dendrimer and its structure, and to obtain the intrinsic viscosity of a dendrimer. A more quantitative relationship between algebras.

1 Theoretical calculations Due to the near-spherical shape of dendrimers, their high degree of branching makes them unable to produce chain entanglement and can therefore be approximated as rigid sphere molecules. Thus, according to Einstein's ratio of viscosity to volume and molecular weight: For a dendrimer, its molecular radius can be expressed by the following formula: where Rc represents the radius of the inner molecule, Db represents the diameter of the branching unit molecule, n is Algebra.

The molecular weight of the n-th dendrimer can be represented by the formula: where Me represents the molecular weight of the core molecule, Mb represents the molecular weight of the branching unit, n is the algebraic number, fc is the functionality of the core molecule, and /b is the branching unit molecule The functionality. The above equation can be changed to: The first n terms are: Xu Min et al.: Relationship between the intrinsic viscosity of a dendrimer and the algebra It can be seen from the above figure that the relationship between the intrinsic viscosity of a dendrimer and the algebra does have a The maximum value appears around the 3rd and 4th generations. Since we have simplified the formula, the algebra () for the diameter and molecular weight of the branching unit molecules are given as 71994-2014 China Academic Journal Electronic characteristics. The algebraic number () can be obtained by taking the derivative of equation (8). Divide equation (8) and make it zero. After simplifying, you can get the following formula: you can see that the prediction result is basically consistent with the experimental data. This further proves the credibility of the theory.

In this paper, the intrinsic viscosity of dendritic macromolecules is calculated theoretically using Einstein's viscosity theory, and the intrinsic relationship between intrinsic viscosity and molecular structure parameters of dendrimer is obtained as follows: