Polymers 1

Flashcards based on lecture notes about polymers, covering definitions, properties, and applications.

What is a polymer?

A large molecule (macromolecule) composed of repeating structural units connected by covalent bonds.

Give examples of polymer usage in pharmacy.

Drug delivery, Formulation, Tableting, Solubilisers, Emulsifiers, Flocculating agents, Gels, Coatings, Wound dressing, Packaging, Recyclable materials, Devices, Inhalers, Injectors/syringes.

What are some applications of polymers?

Tablet matrices, Cell-growth scaffolds, hydrogels, adhesives, Film coating, Surgical devices, micelles, nanoparticles, Colloid stabilisers, Microcapsules/ microspheres, biosensors, membranes, Support for immobilized biomolecules, implants, sutures, Skin-substitutes

List four differences between polymers and small molecules.

State of matter, Dissolution, Solution properties, Mechanical properties

In what states of matter can small molecules exist?

Solid, liquid, and gas.

In what states of matter can polymers exist?

Solid and liquid only (no gas state).

Why don't polymers exist in a gas state?

Polymers are too large/heavy to vaporize, and covalent bonds prevent conversion to gas.

How does the dissolution of small molecules differ from that of polymers?

Small molecules dissolve quickly (seconds to minutes) and disperse immediately, while polymers dissolve slowly in a multi-stage process involving swelling, gel formation, and chain disentanglement.

What are the stages of polymer dissolution?

Swelling, gel formation, and chain disentanglement.

Why do polymers increase solution viscosity more than small molecules?

Due to their large size and chain entanglement.

1.Higher polymer concentration → More entanglements → Higher viscosity.

What properties do some polymers exhibit, which allow them to stretch and return to their original shape?

Elastic properties

Are all polymers elastic?

Not all polymers are elastic—this depends on chemical structure and molecular flexibility.

What are three key features of polymers summarized in the lecture notes?

Polymers can never be in the gas state

The first stage of polymers dissolution is swelling

Polymer solutions have higher viscosity compared to solutions of low molecular weight substances of the same concentration.

Define 'monomers'.

The small repeating units that make up a polymer.

Define 'oligomers'.

A molecule made up of a few monomers.

Define 'macromolecule'.

A very large molecule, such as a polymer.

What is a polymer chain?

A sequence of monomers linked together.

What is meant by the 'degree of polymerisation'?

The number of repeating units linked together in a polymer.

Why do polymers have much higher molecular weights than small molecules?

Due to their repeating unit structure.

On what does the molecular weight (MW) of a polymer depend?

The degree of polymerization (n)—the number of repeating units linked together.

How is the Molecular weight of a polymer calculated?

Mw (polymer) = Mw (repeating unit) × Degree of Polymerisation

What is polydispersity?

A measure of how broad the molecular weight distribution is in a polymer sample.

What does 'configuration' refer to in polymer chemistry?

The fixed molecular architecture of a polymer, determined by covalent bonds.

What is a homopolymer?

A polymer made from only one type of monomer.

What are copolymers?

Polymers made from two or more monomers.

Name four different types of copolymers.

Statistical (random) copolymers, Alternating copolymers, Block-copolymers, Graft-copolymers

Name six different molecular architectures of polymers.

Linear, Ladder, Branched, Dendrimer, Star, Cross-linked

Name some examples of natural polymers.

Polysaccharides (cellulose, starch), Polynucleotides (DNA), Proteins (BSA)

Give examples of polysaccharides and their relevance to pharmacology.

Cellulose, starch, chitosan, alginate, hyaluronic acid are widely used as excipients (binders, disintegrants, gels).

Give examples of proteins and their relevance to pharmacology.

Collagen, gelatin, albumin are used in drug delivery (e.g., albumin nanoparticles) and tissue engineering.

How are polynucleotides relevant to pharmacology?

DNA and RNA are relevant to gene therapy (e.g., mRNA vaccines).

What aspects of solid-state polymers are analyzed?

Intrinsic material properties without solvent interactions.

Name properties that dictate the behavior of polymers.

Chemical identity of the repeat units, molecular weight and on how monomers are built up into the polymer.

Explain how synthetic and natural polymers are designed/modified to produce desired properties.

Synthetic polymers can be designed to produce desired properties, and natural polymers can be chemically modified.

What are the two phases of solid-state polymers?

Amorphous and crystalline.

Describe the structure of crystalline polymers.

OEDERED STRUCTURE: Chains align in regular, parallel arrangements (e.g., folded chains in polyethylene).

Describe the structure of amorphous polymers.

DISORDERED STRUCTURE: Chains are randomly arranged (e.g., rubber, PMMA).

What properties do crystalline polymers exhibit?

High strength, rigidity, and melting points.

What properties do amorphous polymers exhibit?

Flexibility, transparency, and lower density.

What are semi-crystalline polymers?

Polymers exhibit both crystalline (ordered) and amorphous (disordered) regions.

What is the glass transition temperature?

The temperature at which a polymer transitions from a glassy/brittle state to a flexible/plastic state.

What happens to a polymer below its glass transition temperature (Tg)?

It becomes rigid and brittle.

What happens to a polymer above its glass transition temperature (Tg)?

It becomes flexible and deformable.

What impact does molecular weight have on the phases of polymers?

Low MW polymers can melt into a liquid state at higher temperatures, while high MW polymers transition to rubbery or viscous flow states.

What are some different states in which polymers can exist?

Gel State, solution, and solid state.

Name applications of water-soluble polymers.

Increase viscosity of solvents, swell in solution, adsorb at surfaces, form gels and films, to stabilise drug formulations and control release

Give applications of insoluble polymers.

Film-coating materials, surgical dressings, membranes for dialysis or filtration, matrices to envelop drugs and as packaging materials

What is the initial state of polymer dissolution?

Solid polymer (powder/pellet) with amorphous + crystalline regions.

What is the second stage of polymer dissolution?

Water molecules slowly diffuse into the polymer matrix.

Chains begin to swell

What is the third stage of polymer dissolution?

A swollen gel phase forms at the interface.

Chains are partially hydrated but still entangled

What is the fourth stage of polymer dissolution?

Over time, water fully hydrates individual chains resulting in complete dissolution.

What is the difference in dissolution between a polymer and small molecules?

Dissolution process for a polymer is much more complex than small chemical entities

What three layers exist during the dissolution of polymers?

Infiltration layer, Gel layer, and Diffusion layer

Describe the infiltration layer of polymer dissolution.

Water penetrates the solid polymer.

Describe the gel layer of polymer dissolution.

Swollen, viscous barrier (chains partially hydrated).

Describe the diffusion layer of polymer dissolution.

Dissolved chains slowly detach.

Describe dissolution in small molecules.

1.Diffusion layer only: Water penetrates → ions immediately disperse.

1.Fast (seconds/minutes), no intermediate phases.