Polymers PDF

Polymers Dr. Grissel Trujillo de Santiago  Synthetic Natural Polymers Semisynthetic  Synthetic Natural Examples...

Polymers Dr. Grissel Trujillo de Santiago  Synthetic Natural Polymers Semisynthetic  Synthetic Natural Examples Thermoplastics PET Polymers Thermosets PDMS Semisynthetic Examples Examples Proteins Collagen GelMA Carbohydrates GAG’s MeTro Nucleic acids DNA Modified alginates Natural-derived GelMA  Example of polymeric medical devices Joint separators Sutures Catheters Gloves What is a POLYMER ?  Polymer “Poly” (many) y mer (parts) n Polypropilene  3D Structure Amorphous Crystalline One polymer molecule Examples of molecular structures in polymer o - crosslink sites Copolymers  Polymer molecule - structure influence Flexible Rigid Molecular structure more rigid https://www.youtube.com/watch?v=7tH8Xe5u8A0  Polymers Thermoset Thermoplastic Crosslinked networks Entangled polymers/weak Their shape is held by their forces of attraction between covalent bonds molecules Their shape can be changed when heat or shear stress is applied o - crosslink sites  PLASTIC ≠ POLYMER PLASTIC = DEFORMABLE  Polymers Elastomers Crosslinked networks Amorphous polymers Long chains Elastic (recover their original form when they are deformed) ELASTIC ≠ DEFORMABLE  Check at home Wearable electronics https://www.youtube.com/watch?v=c aQ3kRmQwg8 Molecular weight - Polymers VS Chain entanglement  Molecular weight - Polymers Solve Excel sheet at home Average molecular weight Total weight = # molecules Weight average molecular weight WxMx Polydispersity index Activity in Canvas Molecular weight - Polymers VS Chain entanglement Sum of intermolecular forces Union makes force! Plasticizers Molecular distance Chain mobility  UHMWPE Ultra-high-molecular-weight polyethylene Molecular weight 2,000,000-6,000,000 Da Lineal chains – crystalline structure – More strong Crosslinking with gamma radiation – Wear resistance due to wear  PE (polyethylene) It wears and generates particles (sub-micron size) that trigger inflammation – It causes osteolysis around the implant (activation of osteoclasts/macrophages) – The implant fails to fix in the long term  >20 μm