CHEM3712: Introduction to Polymer Science (2021 S2) - Science Assignment Help

Assessment for Part I

1. Why are the physical properties of polymers drastically different to those small molecular materials? 
2. Describe the different behaviour when linear polymers and crosslinked polymers are placed in good solvents. 
3. Using Gibbs free energy to explain “like dissolve like” of nonpolar polymers. (8 marks)
4. Draw the chemical structure of poly(N-isopropylacrylamide)-block-[poly(styrene-co-methyl
   acrylate)].
5. The higher the molecular weight of polymers, the better mechanical properties. However,why it is not desirable to have an extremely high molecular weight of polymer materials?
6. Size exclusion chromatography (SEC) separates the polymer samples according to their property of? 

• electric charge
• hydrodynamic volume
• specific binding to gel phase
• hydrophobic interactions

7.   Calculate the Mn, Mw and Ð for a polymer mixture sample comprising 2 g of polymer molecules having a molecular weight of 50,000 g/mol, 6 g of polymer molecules with a molecular weight of 100,000 g/mol and 3 g of polymer molecules having a molecular weight of 240,000 g/mol. Show your working out and round your answers off to the nearest thousand.

8. A student uses viscometry to measure the intrinsic viscosity of a polymer. It is found that the intrinsic viscosity [?] is 128 ml/g. If the Mark-Houwink constants (K = 0.92 x 10-2 and a = 0.69)

• Use the Mark-Houwink-Sakudara equation to calculate the Mv of this polystyrene sample.
• Calculate the hydrodynamic radius of the polymer using the Einstein-Simha equation (nm).

9. A PNIPAM was synthesized and measured by THF SEC with polystyrene as standard and gave a molecular weight of 5000. Due to their different conformation of PNIPAM and polystyrene in THF, the measured molecular weight is not accurate. Using a universal calibration equation to calculate the more reasonable molecular weight for this PNIPAM sample. Note: Mark- Houwink parameters: polystyrene K=1.28 x10-2 cm3

10. What are the similarity and differences between dendrimers and hyperbranched polymers?

11. In your polymer lab, after the polymerization, if the monomer conversion is not 100%, we often need to do a dissolution (in good solvent i.e. THF)/precipitation (in poor solvent, i.e., />methanol) to remove the residule monomer. Using the polymer dissolution process and
Huggins solution theory to explain this process. 

12. A student made a PNIPAM sample by RAFT polymerization. It is known that the molar extinction coefficient ? (at ?=310 nm) is 11000. The student prepared a polymer concentration of 1.5 mg/mL and measured the UV-Vis. The absorption at 310 nm was 0.81. Calculate the DP value in the structure. 

13. Choose suitable redox active groups to design a full polymer battery that can deliver an output potential >2.5V. 

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