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BME/ME 4814 Exam 1 LATEST 2025 ANSWERS -
COMPLETE QUESTION AND ANSWERS GRADED
A (Worcester Polytechnic Institute)
Tg of a biopolymer is 55C. At body temperature it is likely to be... hard and brittle polylactide is produced by condensation polymerization...True or false False! its produced by ring opening polymerization starch is a.... homopolymer with alpha glucose mers If G' is greater than G'', is a material a viscoelastic solid or liquid? viscoelastic solid biopolymers undergo creep when subjected to stresses inside the body. During this creep, compliance INCREASES with increasing time. True or false? True
if the pKa is smaller, is the degree of ionization greater or smaller? greater at low pressures, the compliance of a vein is how much relative to the compliance of a large artery? 15 times the compliance of a large artery greatest amount of viscoelastic deformation at body temperature? hydroxyapetite, CP Ti, Co-Cr alloy, ceramic, PMMA? PMMA (also PLLA, PEO, PPO) do crosslinked polymers crystallize? no!!! what is the equation for compliance? strain/stress
What is the DOV for metals and ceramics? 1 What is the DOV of skin?
What structural components would make a polymer more hydrophobic? having more CH2 and hydrocarbons What structural components would make a polymer more hydrophilic? COOH or OH groups If the temperature is greater than the LCST for a pluronic the pluronic will be a ...... a gel What types of polymers are sensitive to pH? Acrylics (PAA and NiPAAM)
What polymer is stress sensitive? PVDF What are the most hydrophilic polymers? PEG, PEO, HEMA Which polymers degrade by surface degradation? Polyorthoester, polyanhydride, PTM What is a popular conducting polymer? PANi What is the structure of a micelle? hydrophobic inner core, hydrophilic outside What are the fastest degrading to slowest degrading polymers? anhydrides carbonates esters
EHMWPE
PCL
polyanhydride Na Alginate What is one of the problems with NIPAAM? It is not resorbable NIPAAM is a stimuli sensitive polymer that is: amphiphilic highly hydrophilic mostly hydrophobic highly lipophylic ampiphilic An example of an electroactive shape memory polymer is: polystyrene filled with glass polypropylene filled with kevlar
polyurethane filled with carbon nanotubes PVC filled with TiO PVC filled with Cu nanoparticles Teflon filled with Ag nanoparticles Polyurethane filled with carbon nanotubes One of the primary advantages of a full IPN is that:
- It can be a solution below LCST and form a gel above LCST
- It can be a gel below LCST and form a solution above LCST
- It can be fully a hydrated gel below LCST and form a collapsed gel above LCST
- it can be a collapsed gel below LCST and form a fully hydrated gel above LCST
- It can form a dendrimer below LCST and an inverse micelle above LCST It can be a hydrated gel below LCST and form a collapsed gel above poly(n-ethylmethacrylamide)(PNEMAM) is a polymer with LCST of 58C. So if a solution of this polymer is injected into a physiological site, it will form a gel because of phase separation. True or false? FALSE!!!
False. Molecular weight is lost first followed by mass Which of the following resorbable polymers does not undergo surface erosion:
- PTMC
- polyorthoester
- polyanhydride
- polyhydroxyvalerate polyhydroxyvalerate The drawbacks of NIPAAM are..... the response time is large, mechanical properties are not as good as a pluronic, not resorbable The bioavailability of orally taken drugs is low primarily because of.... first pass metabolism
Which of the following statements is correct:
- AUC for IV delivery<AUC for oral delivery
- bioavailability of most oral drugs is >90%
- polymer based drug delivery systems are not suited for protein based drugs
- polymer based drug delivery can significantly reduce bioavailability but enhance first pass metabolism
- polymer based drug delivery systems can be used to achieve 0 order release polymer based drug delivery systems can be used to achieve 0 order release When a sample of LINEAR NIPAAM polymer with an LCST of 35C is cooled from body temp to 15C it...... becomes a solution What polymer is osteoconductive? polypropylene fumarate Which polymer is likely to have the highest E:
- PDLLA
Can Ti surfaces be made hydrophilic?
- yes with ion implantation, plasma etching, and pegylation What is the surface pore size for hard tissue fixation? 200 - 400nm What material exhibits the lowest amount of stress shielding:
- CP Ti
- 316LSS
- Ti6Al4V
- Mg alloys Mg alloys What is used to fix orthopedic implants for younger patients? Older patients? younger - bony ingrowth
older - bone cement What is the modulus of resilience? the area under the elastic portion of the curve = amt of energy absorbed when stress is applied, energy released when stress is removed What are some problems with nitinol?
- poor fatigue strength
- nickel is toxic for some people How can you improve the integration of Ti6Al4V with bone?
- coat with bioactive materials(HA or bioglass)
- plasma coating or sol-gel coating
- conductive polymer coatings (polypyrrole)
- coating with bisphosphonate
- biofunctionalization
Material for vena cava filter? Nitinol Will plain plasma treating of Ti alloy surfaces increase osteoblast differentiation? YES - it changes roughness and makes it more hydrophilic What are bulk metallic glasses and why are they beneficial?
- higher strength
- low E
- less corrosion
- better cell interactions What ceramics are nearly inert? Al2O3 and ZrO
What ceramics are bioactive? bioglass and HA What ceramics are resorbable? TCP both alpha and beta
- alpha more resorbable but difficult to manufacture What ceramics are osteoconductive? HA, TCP, and Bioglass What makes synthetic HA different from natural HA? synthetic HA is not resorbable and is 100% crystalline and has a constant grain size What are some applications of bioglasses?
- powder and blood to fill bone defects
What polymer has the highest conductivity? PEDOT What are the advantages of NIPAAM? Temperature and pH sensitive, copolymerize easily LCST still there, can form micelles Which polymer has the lowest E:
- PGA
- PDLLA
- PLLA
- PLGA
- PCL
- PHB
- PHV
PCL
What are some problems associated with PLA? Acidic byproducts, bulk degradation, relatively brittle, too stiff for some tissues, difficult to make bioactive, melt can oxidize, Tg is high Arrange these polymers with increasing degradation time:
- PLLA
- PGA
- PLGA
- PCL
- PDLLA PGA PDLLA PLGA PLLA PCL
