To synthesis poly(Styrene methylmethacrylte) I took 14.065g (135mmole) of styrene and 4.515g (45mmole) of methylmethacrylate in 70ml of methanol and 0.303g of AIBN initiator to do solution polymerization. From the proton NMR of Poly(S-MMA) i found ration of Styrene and MMA part is 1:1.18 total product amount is 9.4896g. How can I calculate percentage of yield? and what type of copolymer ( alternatating, random, bolock) form and how to calculate reactivity ratio ?
Dear Muhammad,
1) you realy cannot determine reactivity ratios of monomers from a single experiment.
2) reaction in methanol had to proceed as precipitative polymerization, not as solution polymerization,isn¨t it so? .
3) Published values of the reactivity ratios for radical polymerization of the couple MMA/Sty are both around 0.5 to 0.6, the value for styrene being slightly higher. From it follows that your copolymer should be a statistical copolymer with features towards alternating copolymers - in particular, Styrene units should be mostly isolated (ca 85 %), and built in dyads (ca 12.5 %), the rest triades and longer sequences being seldom. (Valid for monomer ratio of 3 that you mentioned in your question).
You cannot calculate the reactivity ratio from a single composition pair. You are supposed to use the Lewis-Mayo or the Kelen-Tüdős equation to perform the fitting.
Please find attached some literature:
http://www.iasj.net/iasj?func=fulltext&aId=63346
http://www.nature.com/pj/journal/v33/n1/pdf/pj20015a.pdf?origin=publication_detail
http://web.stanford.edu/class/cheme160/lectures/lecture8.pdf
https://www.researchgate.net/publication/230529299_Some_monomer_reactivity_ratios_of_styrene_and_methacrylates_in_the_presence_of_TEMPO
http://nopr.niscair.res.in/bitstream/123456789/17861/1/JSIR%2058(9)%20678-688.pdf
Article Some monomer reactivity ratios of styrene and (meth)acrylate...
Dear Muhammad,
1) you realy cannot determine reactivity ratios of monomers from a single experiment.
2) reaction in methanol had to proceed as precipitative polymerization, not as solution polymerization,isn¨t it so? .
3) Published values of the reactivity ratios for radical polymerization of the couple MMA/Sty are both around 0.5 to 0.6, the value for styrene being slightly higher. From it follows that your copolymer should be a statistical copolymer with features towards alternating copolymers - in particular, Styrene units should be mostly isolated (ca 85 %), and built in dyads (ca 12.5 %), the rest triades and longer sequences being seldom. (Valid for monomer ratio of 3 that you mentioned in your question).
I agree with prof. Jiri vohidal and prof. Gyorgy Banhegyi. However, to find the reactivity ratio of the any monomer pairs, the polymerization must be stooped at 10 % conversion. After that its easy to find the reactivity ratio from the kinetic chain.
The solvents (i.e., DMF, methanol, methyl ethyl ketone) also effects on the values of reactivity ratios of the monomers.
Take DMF as solvent instead of methanol. For reactivity ratio, polymerization is carried out for only 10 to 15 minutes. Before pour into any non solvent, check whether polymer follow out in non solvent or not. If follow out than pour it into larg amount of non-solvent. If not follow out than carried out the reaction for more few minutes and again checked for same. Choose nano-solvent carefully, which soluble the unreacted monomers. Normally, for acrylates solvent as DMF or methyl ethyl ketone and non-solvent as methanol is preferable.
- Badges
- Science topic