Biomaterials and Polymer Science

Vocabulary practice flashcards generated from lecture notes covering biomaterials, surface characterization techniques, and polymer chemistry.

Biomaterial

A non-viable material used in a medical device, intended to interact with biological systems.

Biocompatibility

The ability of a material to perform with an appropriate host response in a specific application.

Toxic Host Response

A host response in which the biological tissue surrounding an implanted biomaterial dies.

Non-toxic and Non-bioactive Host Response

A host response that results in fibrous capsule formation around the non-bioactive implant.

Non-toxic and Bioactive Host Response

A host response where native tissue and cells infiltrate the implanted biomaterial.

Non-toxic, Bioactive, and Degradable Host Response

A host response where native tissue progressively replaces the degrading implant over time.

Ionic Bonding Energy

A very strong interactive force in molecular assemblies with a bond energy of $770\,kJ/mol$.

Covalent Bonding Energy

A strong chemical interaction with a bond energy of $350\,kJ/mol$.

Metallic Bonding Energy

A medium-strong interaction with a bond energy of $300\,kJ/mol$.

Hydrogen Bonding Energy

A medium interactive force with a bond energy of $20\,kJ/mol$.

Collagen Hierarchical Structure

Molecular assembly of collagen progressing from weak collagen tripeptides to microfibrils, fibrils, and strong collagen fibers.

Intrinsic Properties

Bulk material properties that depend on composition only, such as density, heat capacity, and metal stiffness.

Extrinsic Properties

Bulk material properties that depend on microstructure only, such as yield strength and stiffness of polymers.

Hooke's Law

States that the extension of a spring is in direct proportion with the load applied to it, expressed as $F = -kx$.

Nominal Stress

The applied force per unit cross-sectional area, given by $\sigma = \frac{F}{A}$ in units of $N/m^2$ or $Pa$.

Nominal Strain

A dimensionless measure of deformation calculated as $\varepsilon = \frac{\Delta l}{l}$.

True Strain

Strain measure that addresses continuous deformation, expressed as $d\varepsilon_t = \frac{dl}{l}$.

Atomic Force Microscopy (AFM)

High-resolution scanning probe microscopy generating 3D topographic images and measuring physical forces at the nanoscale using a flexible cantilever arm.

Isotropic Material

A material whose physical properties are identical in all directions.

Anisotropic Material

A material whose physical properties vary depending on the direction of measurement.

Yield Strength

The specific stress value at which a material begins to undergo plastic deformation.

Resilience

A measure of the elastic energy that can be stored in a unit volume of a stressed material.

Toughness

The total amount of energy per unit volume that a material can absorb prior to mechanical failure.

Fracture Toughness

A measure of how successfully a material resists crack propagation, dependent on the testing environment.

Creep Failure

Failure occurring when a material is subjected to a stress below its yield strength over an extended period.

Fatigue

Progressive and localized structural damage occurring when a material is subjected to cyclic loading.

Refractive Index

An optical property defined as $n = \frac{c_{\text{vacuum}}}{c_{\text{material}}}$, where $c$ is the speed of light.

Interface

An infinitely thin separation plane representing the transition between two distinct phases.

Interphase

The unique compositional phase located between two contacting phases.

Biomaterial Surface Layers

Interphase zones including metal oxides, adsorbed moisture/organics, or surface-reversing polymer layers like pHEMA.

Contact Angle

A property determining surface wettability; larger angles signify greater surface hydrophobicity.

Zisman Method

States that when a liquid spreads freely on a surface, the surface tension of the liquid is lower than or equal to that of the solid surface.

Electron Spectroscopy for Chemical Analysis (ESCA)

Surface analysis technique based on the photoelectric effect, emitting electrons from matter upon absorption of short-wavelength electromagnetic radiation.

Dynamic SIMS

Secondary Ion Mass Spectrometry using high ion doses over time to cause surface damage, used for depth profiling in metals and ceramics.

Static SIMS

Secondary Ion Mass Spectrometry using low ion doses (sputtering $<100\%$ of surface) to analyze large molecular fragments without surface damage.

Scanning Electron Microscopy (SEM)

Microscopy technique focusing a high-electron beam under vacuum to emit low-energy secondary surface electrons and form a 3D surface image.

Environmental SEM (ESEM)

Low-voltage SEM variant permitting the analysis of non-conductive, wet, and uncoated samples.

Fourier Transform Infrared Spectroscopy (FTIR)

Spectroscopic technique measuring bond vibrations with a penetration depth of $1\text{--}5\,\mu m$ to analyze crystallinity and molecular orientation.

Scanning Tunneling Microscopy (STM)

Microscopy technique using quantum tunneling between a conductive surface and a metal tip $0.5\text{--}1\,nm$ away to generate atom-scale electron density images.

Degree of Polymerization

The total number of repeat units in a polymer chain.

Gel Permeation Chromatography (GPC)

The most common analytical method for determining the molecular weight distribution of polymers.

Polypropylene Repeat Unit

The basic repeating chemical structure of Polypropylene (PP), consisting of a carbon-carbon backbone and hydrogen/methyl pendant groups.

Polymer Architectures

Polymer structures categorized by repeat unit sequence (homopolymers, copolymers) or chain configuration (linear, branched, network, star, comb, dendrimer).

Glass Transition Temperature ($T_g$)

The temperature at which single bond rotation becomes impossible and an amorphous polymer transitions from a rubbery state to a glassy state.

Rubbery State

State of amorphous polymers above $T_g$ where random coils continuously change conformation due to single bond rotation.

Semi-Crystalline Polymer State

Polymer structure comprising both disordered amorphous regions and ordered crystalline domains packed into a regular lattice.

Differential Scanning Calorimetry (DSC)

Thermal analysis method measuring heat supplied to a polymer at a constant heating rate to identify $T_g$ and $T_m$.

Dynamic Mechanical Analysis (DMA)

Thermal characterization technique that measures polymer modulus across a temperature range.

Polyurethanes

Elastomeric biomaterials made of crystalline hard segments and amorphous soft segments, frequently used in cardiovascular devices.

Thermoplastics

Polymers that liquefy when heated and solidify when cooled.

Silicones

Biomaterials featuring an inorganic siloxane backbone of repeating silicon-to-oxygen bonds with organic pendant groups.

Polytetrafluoroethylene (PTFE)

Inert, highly lubricious perfluorinated polymer with high molecular weight ($>10^6$) and high crystallinity requiring twisted chains.

Fluorinated Ethylene Propylene (FEP)

Fluorinated polymer with bulky $\text{CF}_3$ groups that introduce crystalline defects to lower melting point and ease processing.

Polyvinylidene Fluoride (PVDF)

Partially fluorinated polymer exhibiting high flexibility due to small hydrogen atoms, high dielectric constant, and polar solvent solubility.

Hydrogel

A crosslinked network of hydrophilic polymer chains containing over $99.9\%$ water, mimicking natural soft tissue flexibility.

Integrated Polymer Structure Overview

Diagrammatic representation linking repeat unit chemistry (backbone and pendant groups) with chain arrangement and copolymer position.