Name: Chun Ka Yuen (52180145) Group: C
Date of experiment: 30/3/2012 Date of report: 3/4/2012
Experiment 5: Polymers
Aim:
This experiment is to prepare polymeric materials including polystyrene, Nylon6, 10, and cellulose triacetate.
Introduction:
A polymer consists of repeating subunits in the form of –A-A-A-A-A- or A-B-A-B-A-B-, where A and B are different subunits. These sub-units are typically connected by covalent chemical bonds. Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network. Each monomer is incorporated into the polymer is known as a repeat unit or monomer residue. The physical properties of a polymer are strongly dependent on the size or length of the polymer chain. Some of the polymers and their precursors are via radical mechanism or nucleophilic substitution.
In this experiment, polystyrene, nylon 6, 10, and cellulose triacetate were prepared by different mechanisms. Polystyrene was generated via radical mechanism from styrene. Nylon 6, 10 was generated from 1, 6-hexanediamine and sebacoyl chloride with the loss of HCl via nucleophilic substitution. Cellulose triacetate was generated by mixing cotton balls and acetic anhydride with acidic condition under heating.
Materials:
Styrene, 1 M NaOH solution, CaCl2(s), xylene, t-butyl peroxybenzoate, methanol, 5% aqueous solution of 1, 6-hexanediamine, NaOH(s), 5% sebacoyl chloride in hexane, glacial acetic acid, concentrated H2SO4, cotton balls, acetic anhydride, CH2Cl2
Procedure:
For the synthesis of polystyrene, 10 ml styrene and 20 ml of 1 M NaOH solution was placed in separatory funnel and they were shaked for several times. Aqueous layer was discarded. The styrene layer was washed with water and dried with CaCl2(s). The styrene was placed in 100 ml flask and 25 ml xylene and 7-8 drops of the t-butyl peroxybenzoate was added. The