ML

biomaterials exam 3

  1. Nature of chemical bonding associated with thermoplastics, thermosetting plastics, and elastomers:

    • Thermoplastics: These have weak, secondary bonds like van der Waals forces holding their polymer chains together. They soften when heated and can be reshaped.

    • Thermosetting plastics: They have strong covalent bonds between polymer chains and are cross-linked, becoming rigid and non-meltable once set.

    • Elastomers: These have a combination of weak secondary bonds and covalent bonds, allowing them to stretch and return to their original shape due to the reformation of these weak bonds.

  2. Structures of repeat (monomer) units of common polymeric biomaterials:

    • Examples include polyethylene (PE), polylactic acid (PLA), polyvinyl alcohol (PVA), and polyurethane (PU). Each has its own specific chemical structure and properties.

  3. Thermal behavior of thermoplastics and thermosetting plastics:

    • Thermoplastics soften when heated and can be remolded.

    • Thermosetting plastics undergo irreversible chemical changes when heated, becoming rigid and non-meltable.

  4. Influence of molecular weight and morphology on mechanical properties and chemical resistance:

    • Higher molecular weight generally leads to increased strength and toughness but may decrease flexibility.

    • Molecular weight also affects chemical resistance, with higher molecular weight polymers often being more resistant to chemical degradation.

  5. Molecular weight determination based on monomer type and degree of polymerization:

    • Molecular weight can be determined using techniques like gel permeation chromatography (GPC) or by calculations based on the monomer type and degree of polymerization.

  6. Influence of altering the surface of polyethylene/UHMWPE on surface structure and properties:

    • Altering the surface of polyethylene or ultra-high molecular weight polyethylene (UHMWPE) can affect properties like surface roughness, wettability, and biocompatibility.

  7. Types of Copolymers:

    • Copolymers are polymers composed of two or more different monomers. They can be random, alternating, block, or graft copolymers.

  8. Attributes and limitations of silicone elastomers/rubber for biomedical applications:

    • Attributes include biocompatibility, flexibility, and durability.

    • Limitations may include poor adhesion to tissues and susceptibility to degradation over time.

  9. Possible questions on the use of polymerics in vascular, orthopedic, and dental applications:

    • Questions could cover biocompatibility, mechanical properties, wear resistance, and long-term stability of polymer-based medical devices in these applications.

  10. Types of Biodegradable/Resorbable thermoplastic polymers:

    • Examples include polylactic acid (PLA), polyglycolic acid (PGA), and their copolymers (PLGA), polydioxanone (PDO), and polycaprolactone (PCL).

  11. Factors or polymer properties affecting their relative rates of degradation:

    • Factors include chemical groups susceptible to degradation, crystallinity, morphology, environmental conditions (pH, temperature), and the presence of enzymes.

  12. Types of hydrogels and their differences in chemical structure:

    • Hydrogels can be physically or chemically cross-linked and can be natural (e.g., collagen, alginate) or synthetic (e.g., polyethylene glycol, polyacrylamide).

  13. Surface erosion versus bulk erosion in hydrogels:

    • Surface erosion involves degradation starting from the outer surface, while bulk erosion involves uniform degradation throughout the material.

  14. Physical versus chemical hydrogels:

    • Physical hydrogels are reversible and rely on physical interactions for cross-linking, while chemical hydrogels have covalent bonds for cross-linking and are more stable but less reversible.

  15. Categories/types of bioceramics:

    • Bioinert ceramics (e.g., alumina, zirconia) and bioactive ceramics (e.g., hydroxyapatite, tricalcium phosphate) are common types.

  16. Significance of ionic and covalent bonding on properties/behavior:

    • Ionic bonding can lead to ion release and influence biocompatibility, while covalent bonding provides stability and strength.

  17. Mechanical properties of bioceramics relative to metallics and polymerics:

    • Bioceramics are often harder and stiffer than polymers but may be more brittle. They can have excellent wear resistance and biocompatibility.

  18. Influence of pore size within ceramic/ceramic coating on cell/tissue ingrowth:

    • Larger pores may facilitate cell infiltration and tissue integration, while smaller pores can enhance mechanical properties and support vascularization.

  19. Possible questions involving the use of bioceramics in tissue regeneration, orthopedic, or dental applications:

    • Questions could focus on biocompatibility, mechanical compatibility, degradation rates, and osseointegration properties.

  20. Chemical composition of bioglass to make it bioactive:

    • Bioglass typically contains silicon dioxide (SiO2), calcium oxide (CaO), sodium oxide (Na2O), and phosphorus pentoxide (P2O5), which promote bioactivity and bone bonding.

  21. Assessment and testing for FDA approval of medical devices with biomaterials:

    • This involves biocompatibility testing, mechanical testing, sterilization validation, material characterization, and often clinical trials to demonstrate safety and efficacy.