Name: Jeff Chudakoff Partners: Alejandra Garcia Date: 2 December 2011 TA: Mengbin Chen Skill Building Exercise #2 Answer the following questions: 1. What does it mean when a polymer is crosslinked? Crosslinked is one manner in which monomers link together. In this method, separate polymer chains are connected via bonds between the individual polymer chains. 2. We discussed how polymer linking and structure contribute to its properties. How would you expect the density, elasticity, and rigidity of a polymer that is branched to compare to one that is linear?
I would expect the density of the linear polymer to be much higher than the density of the branched polymer, which I would expect to have low density. The branched structure, though, would be more elastic than the linear structure. The linear polymer would be expected to have more rigidity than the branched structure. 3. Consider the following polymer: a. Identify and draw the chemical formula of the monomer from which this polymer is made of. Clearly explain the criteria you used to identify the monomer. State how many carbons, oxygens, and hydrogens can be found in one monomer of this polymer. This is the monomer. C2H4O) In this monomer there are two carbons, four hydrogens, and one oxygen. I identified this as the monomer by looking for the repeating component of the polymer. b. This polymer is hydrophilic. Give a plausible reason for this behavior. Your explanation should be based on the molecular structure of the polymer, the molecular structure of water, and the interactions between molecules of these two substances. You should use terms such as polarity, polar bond, charge, interactions, attractions, repulsions or hydrogen bonds. However, you should use only those terms that apply to this situation.
The polymer is surrounded by hydrogens via hydrogen bonds between the hydrogens and the carbons. This is a polar bond, resulting in hydrogen being relatively positively charged. Water molecules are also polar molecules. The oxygen has a relatively negative charge and, thus, would interact with the polymer. There would be attraction between the oxygen of the water and the hydrogens of the polymer, characterizing a hydrophilic property of the polymer. 4. Nylons are named with two numbers. c. What do the 6 and 10 represent in the name of your product?
The 6 and 10 represent the number of carbons in the two polymer chains that are connected to construct the nylon. The first chain [N(CH2)6N] has six carbons, while the second [C(CH2)8C] has ten carbons. d. Draw the structure of nylon 5-12. 5. We did not calculate the percent yield for our nylon synthesis because we did not have time to fully dry the product, but it is an important aspect of synthesis. Another difficulty is that the polymer chain length can be variable, so the molecular weight of the monomer is used. e. Assume you began with exactly 20. 00 mL of each reactant.
What is the limiting reagent? Show your work. 20. 00mL ? 1L1000mL ? 0. 5mol1L=0. 01mol Hexamethylenediamine 20. 00mL ? 1L1000mL ? 0. 2mol1L=0. 004mol Sebacic Acid Since the mole ratio is 1:1, the one with less is the limiting reactant. Therefore, Sebacic Acid is the limiting reactant. f. What is the theoretical yield in grams of Nylon 6-10? The mole ratio is 1:1; so, we would expect to get the same amount of moles as the limiting reactant (0. 004mol) of Nylon 6-10. 0. 004mol Sebacoyl chloride ? 1 mol 6-10 nylon monomer1 mol Sebacoyl chloride? 282. 42g1mol 6-10 nylon monomer=1. 13 grams 6-10 nylon