2.4 Bioeconomy Resources

Plants and animals produce a handful of building blocks such as:

Structural polymers: proteins and polysaccharides

Energy Storage polymers: starch

Energy storage molecules: triglycerides aka fats

Defense compounds and pigments: terpenoids, natural rubber, carotenoids

Examples of biomass composition (dry matter)

lignin

starch

cellulose

protein

hemicellulose

oil/fats

ash (minerals)

sugar

Estimation of the relative composition of different biomass in the biosphere top 3 (part of lignocellulose >90%)

50% is cellulose→polymer of glucose
24% is hemicelluloses

20% lignin

Estimation of the relative composition of different biomass in the biosphere that consist of the <10% in the food category

Starch

sugar

vegetable oils

proteins, other ingredients

Chemical composition of wood

Carbon 50%

Oxygen 43%

Hydrogen 6%

Nitrogen 1%

What type of material is wood?

A lignocellulosic material composed of cellulose, hemicelluloses and lignin

Most sources of lignocellulose materials come as what?

Most sources of lignocellulose materials come as polymers.

poly

meros

meaning

many

parts

=

polymers

Another name for polymers

macromolecules because they consist of extremely large molecules

Simple definition for polymers

large molecule composed of “simple” repeating units

Large molecule made up of many smaller building blocks called monomers.

molecular weight/molar mass is an important parameter impacting properties

degree of polymerization

number of repeating units

How do you get the degree of polymerization?

Adding the total number of repeating units and chain ends.

eg. if there are 6 chains, the DP= 6

Molecular weight

mass of one mole of molecules, g/mole

for small molecules or monomers

1 mole of water = 18g

1 mole of NaCl= 58.44g

1 mole of glucose = 180g

For polymers

Molecular weight = Mw of repeating unit x degree of polymerization

Molecular weight— Distribution

Average molecular weight

A way to describe the polymer sample as a whole.

Molecular weight— Distribution

Polydispersity

Different chain lengths and molecular weights

How are repeating units in a polymer chain linked?

linked by covalent bonds (sharing electrons; intermolecular interactions); process of forming polymers = POLYMERIZATION

Water bottle: polyethyline terephthalate (PET)

Water: no
Glass: no

dough yes (gluten)

Sucrose no → small molecule

cellulose → yes

Monomers

• “Mono” + “mer” means “one” + “part”

• Small molecules that can react (form covalent bond) to form polymers

The small molecule that joins with other molecules to form a polymer.

Monomers

Can one polymer contain only one type of monomer?

No, you can react 2 compounds together to have a monomer

What happens when monomers join together?

They form a polymer through chemical bonds.

Repeating unit

The group of atoms that repeats along the polymer chain.

The structural unit that repeats along a polymer chain.

Think of it like building a necklace:

• Monomers = individual beads.

• Polymer = the entire necklace.

• Repeating unit = the pattern of beads that repeats.

Multiple polymer chains entangle together to form:

“stuff” at a molecular level

What is the difference between homopolymers and copolymers?

Homopolymers contain one monomer type; copolymers contain two or more.

Classification of copolymers

Random copolymer

Alternating copolymer

Block copolymer

Graft copolymer

What does stereochemistry describe in polymers?

The 3D arrangement of atoms and groups along polymer chains.

What is polymer topology?

Polymer architecture

polymer topology

Linear

polymer topology

branched

polymer topology

star

polymer topology

comb

polymer topology

ladder

polymer topology

semi-ladder

polymer topology

network or crosslinked

polymer topology—Branching affect physical properties

examples of linear polymer plastics

higher density

polymer topology—Branching affect physical properties

examples of branched polymer plastics

less density, more flexible, little crystallinity due to spacing of the branches

Polymer Morphology

What is an amorphous polymer?

A polymer with no long-range order or regular molecular packing.

Polymer Morphology
What happens to polymer chains when a melt cools?

Molecular movement slows down until the chains become frozen in place.

Polymer Morphology

What does atactic mean in polymer structure?

irregular microstructure

Polymer Morphology

Why are atactic polymers generally amorphous?

Random side groups prevent chains from packing regularly

Polymer Morphology

What is the difference between crystalline and amorphous regions?

Crystalline regions are ordered; amorphous regions are disorganized.

What is a semi-crystalline polymer?

A polymer containing both ordered crystalline and disordered amorphous regions.

Crystalline polymers
2 types:

StereoREGULAR polymers → can crystallize, eg. polyethaline

StereoIRREGULAR polymers → cannot crystallize eg. atactic polystyrene, polycarbonate

What are polymer additives? Give an example.

Substances that change polymer properties. Plasticizers increase flexibility.

Examples of polymer terms

Molar mass and dispersity

Polymer architecture “topology”

Polymer morphology — internal packing of chains

Polymer chemistry — co-polymers; block and random

Some analogies

examples of polymers

DNA & RNA

polyethaline

Polyesters

PET

PLA

Classification of polymers — Natural polymers

Polymers produced by living organisms, including plants and animals.

Classification of polymers

What are polysaccharides made of?

Many monosaccharides (simple sugar units) joined together.

Classification of polymers

What is the difference between homo- and heteropolysaccharides?

• Homo = one sugar type;

• hetero = two or more different sugar types.

Classification of polymers

What are the functions of cellulose and starch?

Cellulose provides structural support; starch stores energy in plants.

Classification of polymers

Name three hetero-polysaccharides found in plant cell walls.

Hemicelluloses, pectins and xyloglucans.

Classification of polymers

What are chitin and alginate, and where are they found?

Chitin: insect exoskeletons and fungi.

Alginate: brown seaweeds.

Classification of polymers

What are proteins made of?

Amino acids connected by peptide bonds.

Classification of polymers

Match natural proteins to their sources.

• Collagen: connective tissue;

• Keratin: hair;

• Albumin: egg;

• Fibroin: silk;

• Casein: milk.

Classification of polymers

Match natural proteins to their sources.

COLLAGEN—major amino acids

Glycine

Proline

Hydroxyproline

Classification of polymers

Match natural proteins to their sources.

COLLAGEN—role of glycine in collagen

Glycine's small size allows tight packing and helps form the triple helix.→ gives the helix’s twist.

Classification of polymers

Match natural proteins to their sources.

COLLAGEN—what structure do the three collagen chains form?

A stable, intertwined triple helix.

Classification of polymers

Match natural proteins to their sources.

COLLAGEN—what structure do the three collagen chains form?

Bone, tendons, and soft tissues such as the intestine. Different collagen types (I, II, etc.) occur in different tissues.

Classification of polymers

Match natural proteins to their sources.

SILK PROTEIN (Fibroin)—How many amino acids are found in silk?

approx. 17 different amino acids

Classification of polymers

Match natural proteins to their sources.

SILK PROTEIN (Fibroin)—Which three amino acids make up approximately 86% of silk?

Glycine, alanine, serine

Classification of polymers

Match natural proteins to their sources.

SILK PROTEIN (Fibroin)—How does spider silk compare to silkworm silk?

Spider silk is approximately 2 times stronger than silkworm silk.

Classification of polymers

Match natural proteins to their sources.

SILK PROTEIN (Fibroin)—Which species produces the silk cocoon used in commercial silk production?

Bombyx mori (silkworm)

Classification of polymers

Match natural proteins to their sources.

SILK PROTEIN (Fibroin)—How long can silkworm silk filaments be?

One continuous filament can be 300–900 m long; 1 lb of silk can represent about 1,000 miles of thread.

Classification of polymers

Match natural proteins to their sources.

KERATIN—What is keratin the primary constituent of?

Hair, wool, nails, hooves, horns, and the epidermal layer of skin.

Classification of polymers

Match natural proteins to their sources.

KERATIN—What is the primary structure of keratin?

A superhelix (coiled-coil) made of two alpha-helices bundled together

Classification of polymers

Match natural proteins to their sources.

KERATIN—Which amino acid in keratin contains sulfur?

Cysteine, which contains a sulfur-containing thiol (-SH) group.

Classification of polymers

Match natural proteins to their sources.

KERATIN—What do disulfide bonds do in keratin?

Crosslink chains, making keratin stronger and less soluble (insoluble).

Classification of polymers

Match natural proteins to their sources.

KERATIN—How are alpha-keratin chains strengthened?

Alpha-helical chains are crosslinked through disulfide bonds.

Classification of polymers

Match natural proteins to their sources.

KERATIN—Besides cysteine, which amino acids are abundant in keratin?

Proline and serine.

Protein vs Cellulose

Protein

Monomer → amino acids

Primary Structures → polypeptide chain, Amide/peptide linkage

Secondary structure → alpha helix, Beta-sheet, Intra and inter - molecular H bond

Tertiary Structure → The three dimensional structure, globular structure, hydrophobic interactions

As they go further, they turn into 3D complex structures.

Protein vs Cellulose

Cellulose

Monomer → glucose

Primary Structures → Cellulose chain, ether linkage

Secondary structure → Elementary fibrils, 36 chains Intra- and Inter- molecular H-bond, Van de Walls Interactions

Tertiary Structure → Microfibers

As they go further, they get bigger.

Proteins and Amino Acids

how are proteins composed?

Amino acids are linked to form polypeptides through the peptide bond.

→ The reaction of the formation of the peptide bond, in which a carboxyl group and an amine group are joined together with the exclusion of a water molecule.

Proteins are made up of amino acid building blocks

Proteins and Amino Acids
Some examples of amino acids encoded in proteins

Glycine

Serine

Cysteine

What does it mean for amino acids to be zwitteronic?

Amino acids can be both negatively and positively charged; it may also depend of pH levels.

Amino groups can be either hydrophobic or hydrophilic

What types of structures can polypeptides and proteins form?

helices and sheets

What determines the properties and characteristics of helices and sheets?

amine and carboxyl acid

alpha helix

B sheets

polypeptides

aminoacids, dipeptide, tripeptide…