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Synthetic Polymers As Biomaterials - Coggle Diagram
Synthetic Polymers As Biomaterials
Synthetic Polymers
that are used in Biomedical Applications
Synthetic Polymers play an important role in medical therapy, used for various applications
Implantable Devices
Prostheses
Bone Repair
Dentistry
Opthamology
Drug Deliver Systems
Wound Healing
Tissue Engineering
Artificial Organs
Inert in nature & have many fabrication options
Produced by chemically linking monomers into long molecular chains
Monomers can be:
Gaseous
Ethylene
Gives Polyethylene
Liquids
Methyl Methacrylate
Gives Polymethyl Methacrylate (PMMA, Perspex)
Hydrocarbon chains (OH)
Called "Fake Glass"
Solids
Terephthalic Acid
Gives PET when combined with ethylene glycol
Polymer Structure
Basic makeup is Carbon & Hydrogen
Other Elements can also be involved
Oxygen
Polyester & Polycarbonates
Chlorine
PVC
Desirable for use in sterile environments, such as hospitals
Fluorine
Teflon
Nitrogen
Nylon
Silicon
Polysiloxanes & Polyphosphazenes
Phosphorous
Sulfur
Should understand repeating units, but don't need to know polymer chains verbatim
Types of Polymers
Thermosets
Strengthens when heated, can't be remolded
Thermoplastics
Can be reheated, remolded, and cooled w/o causing chemical changes (glass transition temp)
Elastomers
Classification based on mechanical properties
Hydrogels
Classification based on chemical properties
Polyelectrolytes
Classification based on chemical properties
Biodegradable
Classification based on biostability
Breakdown under certain conditions
Cleavage of chains, cross-links, or both
Subverts long-term biocompatibility issues
Also called bioerosion, bioabsorption, biorespoption
Erosion
Water insoluble, but breaks down to water soluble products
Absorption/Resorption
Cellular activity such as phagocytosis
Polymer Source of Origin
Naturally Ocurring
Proteins
Starches
Cellulose
Semisynthetic
Cllulose
Diacetate
Synthetic
Plastics
Polystyrenes
Polyethylene
Properties
Important Characteristics
Thermal & Electrical Insulators
Silicone rubber
Ethylene Propylene Rubber
Resins & Polytetrafluoroethylene (Teflon)
Generally have very light mass w/ varying degrees of strength
Can be processed in various ways to produce thing fibres or very intricate parts
Polycarbonate (PC) is a thermoplastic polymer known for its exceptional transparency, high impact resistance, and thermal stability. These properties make it a popular choice in various choice, including aerospace manufacturing.
Resistant to Chemicals
Mechanical
Rubbery
Extension of several hundred %
Free motion
Low modulus
Glassy or Semicrystalline
Higher Modulus
Often Brittle
Crystal structure & % define mechanical properties
Thermal
Tg = Glass Transition Temp
Below, polymers are glassy & hard
Above, polymers are rubbery
Tm = Melting Temp
Point at which crystalline regions melt
Modulus Varies w/ Temp
Response depends on crystallity & cross-linking of polymer
Biocompatibility & Biostability
Depends on materials & cellular activity of host implantation site
Biocompatibility depends on Protein Binding
Biocompatibility
Ability of a material to perform with an appropriate host response in a specific application
Biostability
Ability of a device to resist undesirable effects by normal host biological defence mechanisms
Material Applications
Polyethylene (PE)
Most consumed in the world
5 Major Grades
High Density (HDPE)
Low Density (LDPE)
Linear Low Density (LLDPE)
Very Low Density (VLDPE)
Ultra High Molecular Weight (UHMWPE)
PE Implants
Porous synthetic polymers that are bioinert & non-degradable in the body
Porosity allows for soft tissue & vascular growth
Joint Reconstruction
Gold standard for hip & knee
MEDPOR Implants
Use HDPE
Replace/Augment underlying bone & soft tissue of face & head
Polyvinylchloride (PVC)
Amorphous & rigid due to large Cl side group
Plasticizers are used to make it flexible
Used for blood/solution storage bags, surgical packaging, tubes, catheters, cannulae
Features
Ideal for blood contact
Good transparency
Flexible & resilient
Non-wetting surface
Polymethylmethacrylate (PMMA)
Amorphous, light, transparent, high biocompatibility
Uses
Used for dentures, bone cement, wrinkle reduction
Can be used for intraocular lens replacement in eye
Vertebral Augmentation (Vertebroplasty)
Vertebroplasty = Fixing the Vertebral Body
Metal needle is passed into vertebral body & cement mixture containing PMMA are injected
Cement hardens rapidly & walls