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Experimental Determination of Reactivity Ratios in Alternating Copolymerization

Learn how to experimentally determine reactivity ratios in Block Copolymerization, understand the impacts of reaction conditions on structure and reactivity, and analyze relative reactivities in polymerizations.

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Experimental Determination of Reactivity Ratios in Alternating Copolymerization

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  1. Alternating Copolymerization Drift: r1, r2 > 1 block azeotrope r1, r2 <1 alternating finally Block COPOLYMERIZATION , HW #6. Solve S.S. expression for a monomer concentration and substitute into the original composition equation which contains the active center. You can get eq. in terms of active center concentrations and if necessary define new kind of new reactivity ratio in eq.

  2. Experimental Determination of r1 & r2 Experimental Determination of r1 & r2 • Mayo and Lewis rearrange copolymer eq. and can get monomer comp copolymer comp.     then vary r1 value (put) and iterate

  3. Experimental Determination of r1 & r2 2. Finemann and Ross Recall B A at low conversion

  4. Relationship Between ξand F1, f1 Relationship Between ξand F1, f1 Material Balance for M1 where [M] = total moles of monomers decrease of M1 monomer

  5. Effect of Reaction Condition Reaction medium Depend on Solubility, PH, Viscosity, Polarity Temperature But the effect of temperature on r is not large Pressure But the effect of pressure on r is not large Reactivity Next page

  6. Effect of Reaction Condition Structure and Reactivity I. Resonance Stabilization II. Polar Effects III. Steric Effects • I.Resonance Stabilization * Walling’s “Free Radicals in Solution”

  7. Structure and Reactivity Define rA, rB : monomer reactivity ratios RA, RB : active center reactivity ratios

  8. Structure and Reactivity TABLE I. Propagation Rate Constants, Monomer Reactivity Ratios, and Active Center Reactivity Ratios for Radical Chain-Growth Polymerizations1 1-All values are based on data collected at 60℃ 2-AN=acrylonitrile; MA=methylacrylate; MMA=methylmetacrylate; STY=styrene; VA=vinyl acetate

  9. Structure and Reactivity Active Center Reactivity Ratios vs. Monomer Reactivity Ratios Relative reactivity of the monomer when then when The effect in relative reactivity of the active center is more stronger than that of monomer. The monomer reactivity gets affect in opposite way comparing to the active center reactivity.

  10. Structure and Reactivity Table 6-3. Relative Reactivates(1/r) of Monomers

  11. Structure and Reactivity Substituent Effects Φ, CH2=CH- > -C≡N, -COR > -COOH, -COOR > -Cl > -O-COR, -R > -OR, -H monomers increase relative reactivity by resonance stabilization. The resonance stability of the monomer increases the reactivity of the monomer. The resonancestability of the radical is weakened reactivity of the radical. Table 6-4 Rate Constant(k12) for Radical-Monomer Reactions

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