Polymers

What is a polymer?

A polymer is a substance made of many repeating units (monomers) bonded together.

What are the three basic types of solid materials?

Metals, Ceramics, and Polymers.

What does 'polymer' mean?

'Poly' means many, and 'mer' means unit – thus 'many units'.

What are examples of natural polymers?

DNA, silk, wool, cellulose, proteins.

What are examples of synthetic polymers?

Polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide (PPO).

What are the five main structural types of copolymers?

Block, Random, Alternating, Graft, and Homopolymer.

What are the three types of polymer morphologies?

Linear, Branched, and Network.

What is the importance of polymer arrangement in copolymers?

The structure (e.g., block vs random) affects polymer properties such as hydrophobicity and application-specific behavior.

What types of intermolecular interactions exist between polymer chains?

Hydrogen bonding, covalent bonding, ionic interactions, dipole-dipole, Van der Waals forces, hydrophobic/hydrophilic interactions.

What is Tg in polymers?

Glass transition temperature; the point where amorphous polymers go from rigid to rubbery.

What is Tm in polymers?

Melting temperature; the temperature at which crystalline regions begin to flow.

What is the difference in softening behavior between amorphous and crystalline polymers?

Amorphous polymers soften over a broad range (Tg), while crystalline polymers soften sharply at Tm.

What is the behavior of thermoplastics?

They soften when heated, harden when cooled, and can be reheated.

What is the behavior of thermosets?

They become rigid upon heating and cannot be remelted.

What are the three key environmental factors affecting polymer performance in the body?

Temperature, pH, and water/moisture.

What is a biostable polymer?

A polymer that does not degrade over time in a biological environment.

What is a biodegradable polymer?

A polymer that degrades and is removed from the body over time.

What are the main chemical degradation mechanisms?

Hydrolysis and enzymatic degradation.

What are examples of enzymes involved in degradation?

Trypsin, α-chymotrypsin, papain, esterase, hyaluronidase, chondroitinase.

What is oxidative degradation?

Degradation due to radiation, oxygen attack, or reactive oxygen species from inflammation.

How does increasing hydrophobicity affect hydrolysis?

Decreases the rate of hydrolysis.

How does increasing molecular weight affect hydrolysis?

Decreases the rate of hydrolysis.

How does increasing crystallinity affect hydrolysis?

Decreases the rate of hydrolysis.

How does increasing porosity affect hydrolysis?

Increases the rate of hydrolysis.

How does increasing Tg affect hydrolysis?

Decreases the rate of hydrolysis.

What is a hydrogel?

A water-swollen polymer network held together by various interactions.

What are the primary mechanisms of hydrogel cross-linking?

Covalent bonding, ionic forces, hydrophobic interactions.

What is mesh size in hydrogels?

The distance between cross-links in a polymer network.

What affects swelling in hydrogels?

Cross-linking density, functional group availability, and mesh size.

What are three lab-used hydrogels and their cross-linking types?

PVA (covalent), Alginate (ionic), Pluronics (hydrophobic interactions).

What are common results of polymer degradation?

Decrease in molecular weight, mechanical strength, swelling changes, mass loss, surface cracking, brittleness.