4.2.3 - macromolecules: proteins, polymers and carbohydrates Flashcards
what are synthetic polymers?
plastics formed through addition reactions
what are 3 types of synthetic polymers?
- LDPE/HDPE
- PP
- PTFE
what factor will effect the strength of the dispersion forces?
- density
How do weak IMF affect LDPE/HDPE?
they make the plastic:
- soft
- flexible
- transparent
- low MP
- low tensile strength
How do strong IMF affect LDPE/HDPE?
they make the plastic:
- rigid
- tougher
- opaque
- higher MP
- higher tensile strength
what conditions cause LDPE/HDPE to become weaker?
- high temperatures
- high pressures
- causing randomness in structure (branching) making the structure more amorphous
what conditions cause LDPE/HDPE to become stronger?
- low temperatures
- low pressures
- causes order in structure (no branching) making the structure more crystalline?
why is the methyl group positioning important on polypropene (PP)?
because changing the packaging will effect the strength of the dispersion forces
define isotactic
strongest IMF being the most rigid and less flexible
what are the properties of polytetrafluoroethene (PTFE)?
- biodegradability
- biodegradability: formed via an addition reaction that is not able to be broken down naturally
define atactic
weakest IMF being the least rigid (lowest strength) and highest flexibililty
define syntactic
not as strong as isotactic but stronger than atactic
define tensile strength
- Depends on the positioning of the methyl side group (tacticity).
- Higher tensile strength is more rigid, stronger and less flexible
order the dispersion forces; isotactic, syntactic and atactic in terms of strength
- isotactic > syntactic > atactic
- due to the small side group
define biodegradability
formed via an addition reaction that is not able to be naturally broken down
define density
depends on the positioning of the methyl side group (tacticity)
what are the properties of polytetrafluoroethene (PTFE)?
- tensile strength
what are the properties of polytetrafluoroethene (PTFE)?
- density
density: high density due to size of fluorine allowing for polymer chain to pack tightly
what are the properties of polytetrafluoroethene (PTFE)?
- reactivity
- high unreactive and chemically inert - good for nonstick as it doesnāt interact with other chemicals
how are polyesters formed?
- reaction between a carboxylic acid and an alcohol to get the original monomer
- condensation reaction
what are the properties of polyester?
- biodegradability
- biodegradability: through a condensation polymer this is not able to be naturally broken down
what are the properties of polyester?
- tensile strength
- the benzene ring will allow tight packing of the polymer increasing the dispersion forces
what are the properties of polyester?
- density
the benzene ring will allow tight packing of the polymer increasing the disperion forces
how are polypeptides formed (1 degree structure)?
- polymerisation occurs by condensation, to form peptide (amide) bonds giving rise to dipeptides and polypeptides
how does the hydrolysis of polypeptides occur?
- identify the amino acids in a peptide link
- identify the -CO-NH- link
- split the protein thorugh the -CN- link
- bring in water and add an OH to the -CO and H to the -NH
- if 3 amino acids you need 2 waters (1 water for every peptide bonds you have to break)
- if provided a chain should be able to name the amino acid (in data book)
answer question in photo
check with answer in photo
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what does the glucose structure look like?
what is the monomer of carbohydrates?
monosaccharide
what is a monosaccharide?
- general formula (CH2O)n where ānā is usually between 3 and 6
- ## eg. glucose, galactose and fructose
what does the galactose structure look like?
what does the fructose structure look like?
recall the disaccharides formed from:
- glucose + glucose
- glucose + fructose
- glucose + galactose
what bond is formed when monosaccharides form disaccharides?
glycosidic
what substance is starch made up of?
alpha glucose units, made up of amylose and amylopectin
what is amylopectin made up of
- 1,4 linked alpha-glucose molecules, and branches via 1,6 linkages
- form spirals or granules that are not tightly packed due to the branching
what is amylose made up of?
- a very long, unbranching chain of several thousand 1,4 linked glucose molecules, and these chains curve to coil up into helical structures for compactness (spirals)
- amylose chains are usually longer than amylopectin
- harder to break down due to the to tighter packing of the molecule
how are glycogen molecules formed?
- condensation reaction forms them
- made of alpha glucose
- branched structure (more than amylopectin)
- allows it to be broken down more readil as it is a temporary energy storage
- bonding between carbon 1,4 and 1,6
how is cellulose formed?
- cellulose is a polymer of beta-glucose
- to form glycosidic 1,4 bonds, subsequent glucose molecules must be at 180 degrees to each other, (upside down to the other) to allow the -OH and -HO groups to bond
- known as syntactic - allows for tighter packing so stronger IMF
how are microfibrils formed from cellulose?
- between 60-70 cellulose molecule become toghtly cross linked to form bundles called microfibrils, which are in turn held together in bindles called fibres by further hydrogen bonding, making the entire structure even stronger
summary of polysacharides
what are the properties of carbohydrates?
- biodegradability
biodegradability: condensation polymer which can be broken down with hydrolysis
what are the properties of carbohydrates?
- tensile strength
tensile strength: this will depend on the degree of branching and packing ability of the carbohydrate
what are the properties of carbohydrates?
- density
density: this will depend on the degree of branching and packing ability of the carbohydrate
how can polymers and disaccharides be broken down into monomers?
hydrolysis reactions - adding water to break the molecule
what makes a substance biodegradable?
- some polymers can be broken down naturally by enzymes in bacteria
what affects the tensile strength of a substance?
- the higher the tensile strenth the more rigid and less flexible
aspects of a polymer that alter tensile strength: - chain length: longer chains = stronger polymer
- side groups: polar side groups give stronger attraction between polymer chains
- branching: straight, unbranched chains can pack together more closely than branched chains
- cross-linking: polymer chains linked toegther by covalent bonds (stronger than IMF)
how does density affect the polymer?
relates to how tightly packed
- eg. LDPE (branched), HDPE (linear)
Influencing factors include:
- chain length (primary structure)
- chain branching (primary sturcture)
- intra/interchain bonding (tertiary and quartnery structures)
- size of side chains
