polymer assignment 1 – exclusivewritings.com

Need help with questions below. Please free plagiarism and no chegg, try to make it as short as you can (typed in word doc please)

1.Ethylene (CH2═CH2) and propylene (CH2═CHCH3) are each separately polymerized to yield polymer A and B respectively. Which of the polymers would have a higher glass transition temperature? Which would more likely be crystalline? Explain your answers. (only answer the crystalline portion)

2.Explain the difference between branched and cross-linked polymers. Which would be expected to be more stiff? Why?

3. What is the difference between isotactic, syndiotacytic, and atactic forms of polymers? Which are more likely to be crystalline in nature?

4.You are given two samples of the same polymer. One is amorphous and the other is mostly crystalline. Which will be more difficult to dissolve in a solvent? Which is more likely to be opaque?

5.The average molecular weight of a sample of PMMA (Figure 6.8) is 75 650. What is the degree of polymerization for the specimen?

6.Three polymer samples with the following properties are mixed together to get 1 kg of polymer mixture. What is overall Mn?

7.Poly(ε-caprolactone) is being considered as a potential material for a vascular graft. After a particular batch has been made, someone gives you the following fractional distribution data and asks you to calculate M n , M w and PI for this polymer.

Wi0.100.100.300.40 0.10

Mi (kg/mol) 25304070 100

8.You are examining a copolymer for its potential as a material for a vascular graft. You are trying to determine whether you want a high or low degree of crystallinity in the material. What type of structures for copolymers have a higher probability for crystallization?

9.How do polyesters such as PLA and PGA degrade? What are some properties that affect their rate of degradation? Explain how autocatalysis can influence their degradation.

10.What is the difference between protein-based and polysaccharide-based materials?

11.In general, what is the molecular difference between collagen and elastin?

12.List the different criteria that natural materials need to satisfy in order for them to be used in biomedical applications.

13.Receptor binding motifs such as RGD have highly selective recognition for cell adhesion. Outline a strategy for incorporating a cell adhesive recognition domain to a biomaterial. Address the problems surrounding domain quantity, type, and affinity in your discussion. (Outline a strategy discussed in class to attach RGD protein to the surface of a polystyrene material and address issues such as domain quantity type, and affinity of the protein for your chosen surface modification)

14.Concisely describe the differences between focal contacts and hemidesmosomes. What would be the implications of excessive formation of either at a biomaterial surface taking into consideration normal cell functions such as motility and mitosis?