AIM: The aim of the experiment was to prepare three different polymers, namely nylon 66, Agar Gel and slime, being able to differentiate between the configuration and analysis among the three structures, noting the physical characteristics of each polymer and the chemical reactions that occur during the formation of the polymer.
Pre- lab questions
1. Is Nylon 66 a step or chain – growth polymer? Define both types of polymerization in your answer. Nylon 66 is a step-growth polymer
Step-growth polymerization, also known as condensation polymerization, eliminates one small molecule when two monomer units are joined together. Chain-growth polymerization, also known as addition polymerization, joins monomer units without loss of atoms. (Blackman et al. 2012)
2. Draw the repeat unit in polyvinyl alcohol (PVA)
3. What do you understand by the term ‘cross-link’? Draw the structure of slime and circle the cross-links. Cross-links refer to the bonds formed when polymer chains are joined together.
Figure 1: Borax forming slime (Source: www.gcsescience.com)
4. Name a biopolymer and identify its monomer unit(s).
Cellulose is a biopolymer formed from joining monomers of glucose.
Polymers basically are macromolecular substances that are joined by large quantities of small similar looking units called monomers. This process is called polymerization. (Blackman et.al, 2012) There exist two types of polymerization, step growth also known as condensation polymerization and chain growth polymerization, also known as addition polymerization. Polymers are of large sizes; therefore, adding or removing rows of atoms does not really affect the properties of the macromolecules. (Blackman et.al) It may be difficult to know the molar mas of a polymer since polymers contain several individual chains that occur in different lengths and sizes. The most important properties of polymers are their shape and size. Polymers tend to crystallize upon precipitation or when they are cooled from a molten state. Different polymers observe different degrees of crystallinity, such as having hydrogen bonds. As the degree of crystallinity of a polymer increases, the melt transition temperature (Tm) increases. There is also an increase in stiffness and strength (Blackman et al. 2012). During this experiment, 3 polymers having different properties were made. Their physical properties and chemical properties were observed and recorded. Nylon, agar and slime were prepared.
Part A: Synthesis of Nylon 66
1. 10ml of Nylon solution A (5% adipoyl dichloride in hexane) was placed in a 50 ml beaker. 2. 10 ml of Nylon solution B (5% hexanediamine in water) was poured into a second beaker. 3. The beaker containing solution B was tipped at a slight angle, then solution A was slowly added by gently pouring it down the side of beaker B. Solution A formed a separate layer on top of solution B. A film of nylon formed between the layers. 4. The walls of the polymer strings were gently freed using a wooden skewer. The nylon film was touched at the interface of the two layers and the tip gently agitated. This made the nylon stick to the wood. It was gently pulled out of the beaker, by wrapping the film around a test tube by slowly rotating the tube and pulling the thread from the beaker. 5. The nylon was thoroughly washed under a gentle stream of water and then slid off the test tube. 6. The properties of the nylon were observed and recorded in table 1 7. Some of the nylon strands were dried by being spread on a piece of paper towel. Once they were dried, their properties were observed and recorded. 8. At the end of the experiment, the solid strands of nylon were thrown in the bin.
Part B: Formation of the 4% Agar Gel
1. 2g of agar was weighed in a 250ml beaker.
2. 50ml de-ionized water was added to the beaker and the resulting solution was heated on a steam bath...