Flashcards in Materials Revolution Deck (28):
what is the structure of ammonia?
3 hydrogen atoms bonded to a central nitrogen atom- lone pair on N
What is the structure of amines?
Same as ammonia but one or more of the hydrogens is substituted for an alkyl group.
What properties is the lone pair on the nitrogen in amines responsible for?
they can act as bases, nucleophiles, ligands
What is a secondary amine?
Where the nitrogen atom is bonded to two alkyl or aryl groups
what is an aryl group?
a benzene ring with one hydrogen substituted eg phenyl, C6H5 -
Name this amine:
Name this amine:
What happens when amines dissolve in water and why?
they form weakly alkaline solutions as they are bases
What can amines accept a hydrogen ion from?
water/ an acid
What is formed when a primary amine reacts with a halogenoalkane?
What is the amine acting as?
A secondary amine
when hydrogen atoms on an amine are replaced by alkyl groups what type of reaction is this?
An alkylation reaction
What type of reaction do amines undergo with acyl chlorides?
What is the product?
An acylation reaction, forming a secondary amide.
what is the general formula of a primary amide?
R group, NH2 group and =O bonded to a carbon
What is different about a secondary amide?
One of the H groups on the nitrogen is substituted for an R group
what bond is broken when amides are hydrolysed?
The C-N bond
what are the products of acid hydrolysis of amides?
a carboxylic acid and an alkyl ammonium ion
what are the products of alkaline hydrolysis?
a carboxylate anion and an amine
What happens in condensation polymerisation?
Two monomers join together to form a condensation polymer and a small molecule such as water or HCl is eliminated.
What must monomers have to form a condensation polymer?
reactive groups at each end
what are crystalline regions and when is there a higher percentage of them?
Parallel strands packed close together that make the polymer stiffer
when it is cooled
what are amorphous regions?
Randomly arranged chains that make it more flexible
What is the glass transition temperature?
when a polymer is cooled this is reached and it becomes brittle and glass like
what imf are between polyesters?
what imf are between polyamides/nylons?
what does copolymerisation do?
adds side groups which pushes chains apart and lowers Tg
what do plasticisers do?
allow chains to slide over each other easily lowering Tg
how does cold drawing make polymers stronger?
as its stretched a neck forms where chains are aligned so more imf can form