Tprinciple of wet spinning process-Part 7 Affects solubility about structure

   Affects solubility about stucture

(一）Infuence of macromolecular chain structure

1. The stronger the intermolecular force,the less likely the polymer is to dissolve.The intermolecular force is t,If the solution can weaken the forces between the macromolecules,it will increase the solubility of the polymer.For example, monomers with low polar functional groups such as methyl acrylate and methyl methacrylate are copolymerized with acrylonitrile, and the solubility of the acrylic copolymer obtained is much greater than that of the acrylonitrile homomer.

2.The more hydrophilic the functional groups on the main of macromolecules are,the more soluble the polymer is.On the polyvinyl alcohol molecular chain,If it contains 3% ~ 15% mol of residual acetate group, its solubility is higher than that of completely saponified polyvinyl alcohol. Furthermore, the longer the hydroxyl group and the residual acetate group are distributed alternately in the macromolecular chain, the lower their solubility is.  A small amount of ethyl, ethoxyl and ester groups were added to the hydroxyl group of cellulose, which significantly increased the solubility of cellulose in alkali and even in water.  

Effect of degree of esterification on solubility of cellulose carbamate

Table 4.2 Dissolution of cellulose carbamate with different nitrogen content

3.The worse the homogeneity of functional group distribution on the main chain of macromolecules,the higher the solubility.Polyvinyl alcohol with irregular spatial arrangement of residual acetate group has high solubility.  This is because the molecular chain with irregular structure has poor crystallization ability, and the polymer has low crystallinity and high solubility.

4.The more flexiblle the polymer chain,the more soluble it is.For example, polymers with rigid molecular chains have limited swelling in a solvent at room temperature and can only dissolve at high temperatures.  

Arlene: poly (p-benzoyl p-benzoediamine) is only soluble in fuming sulfuric acid.  

5. The higher the polymer crosslinking degree,the lower the solubility.Introducing a few chemical crosslinking points into the polymer chain will decrease the solubility obviously  

6. The higher the molecular weight of polymer,the lower the solubility,The intermolecular force ratio of polymers with higher molecular weight is larger, so the solubility of polymers decreases with the increase of molecular weight.  The presence of oligomer is beneficial to weaken the intermolecular forces and improve the solubility  

Protein is a peptide bonded linear polar polymer compound formed by condensation and dehydration of a variety of amino acids. Its molecular structure can be expressed as follows:  

- HNCHCO - HNCHCO - HNCHCO - HNCHCO -  

Ri Rj R3  

The molecular weight of soybean protein is unevenly distributed, ranging from 8000-600000.  

Hydrogen bonds can be formed between amino and acyl groups in the same polypeptide chain of a protein.