How do you polymerize styrene?
Styrene readily polymerizes to polystyrene by a relatively conventional free radical chain mechanism. Either heat or initiators will begin the polymerization. Initiators thermally decompose, thereby forming active free radicals that are effective in starting the polymerization process.
How can you prevent polymerization of styrene?
Some compounds known to inhibit the polymerization of styrene are tert-butylcatechol (TBC), hydroquinone (HQ) and, the methyl ether of hydroquinone (MEHQ); elemental sulfur has also been employed.
How does raft polymerisation work?
RAFT is a type of living polymerization involving a conventional radical polymerization which is mediated by a RAFT agent. Monomers must be capable of radical polymerization. There are a number of steps in a RAFT polymerization: initiation, pre-equilibrium, re-initiation, main equilibrium, propagation and termination.
What is runway polymerization?
A runaway polymerization is a potentially dangerous reaction in which chemical products form with excessive speed, producing heat that may lead to an explosion or other hazards.
What is polymerization of styrene?
Polymerization of Styrene. Polystyrene (PS) is one of the largest volume vinyl polymers, used in countless products from food-packing and plastic cutlery to house insulation. The most common method is free radical polymerization, using benzoyl peroxide as initiator.
What happens if polymerization is inhibited?
This polymerisation is undesirable, as it can foul the fractionating tower, it is also typically exothermic which can lead to a runaway reaction and potential explosion if left unchecked.
Why does living polymerization occur?
Living polymerization is a popular method for synthesizing block copolymers since the polymer can be synthesized in stages, each stage containing a different monomer. Additional advantages are predetermined molar mass and control over end-groups.
What is meant by polymerization?
polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three, or more different compounds.
How does Nitroxide Mediated Polymerization ( NMP ) work?
Nitroxide mediated polymerization (NMP) is another controlled radical polymerization method. It allows the preparation of well-defined polymers with controlled molecular weight and narrow distribution and to extend chains with different monomers to produce multi-block copolymers. A combination of a nitroxide and a free radical initiator
Can a NMP be used to synthesize gradient copolymers?
Using NMP, it is also possible to design and synthesize well-defined polymer architecture such as star, comb, and gradient copolymers as well as polymers with a wide range of functionality. NMP is relatively easy to perform since it requires only the addition of a stable radical nitroxide compound to an otherwise conventional FRP.
How is NMP used to prepare biomaterials?
NMP allows the preparation of very well-defined polymers with controlled molecular weight and narrow molecular weight distribution and to extend chains with different monomers to obtain multiblock copolymers. V. Hasirci, N. Hasirci, in Comprehensive Biomaterials II, 2017
What are some of the limitations of NMP?
The main limitation of NMP is the availability of a range of monomers that can be effectively controlled. Some alkoxyamines and nitroxides are able to control most of the conjugated vinyl monomers.