POLYMERIZATION IN THE CRYSTALLINE STATE. II. ALKALI ACRYLATES AND METHACRYLATES
Alkali acrylates and methacrylates were irradiated with gamma rays at - 78 deg C and their subsequent polymerization was studied in vacuo at 0 to l55 deg C. Potassium acrylate proved to be the most rapidly polymerizing solid monomer studied; it reacted at 0 deg C faster than the lithium salt at l01 deg C or the sodium salt at l20 deg C. The reaction rate of the acrylates decayed rapidly at low polymer yields which were, for long polymerization times, linear in the logarithm of time. The activation energy for the polymerization of potassium acrylate was l6.7 kcal/mole. The chain length of the polymer was, in all kinetic runs except one, independent of the polymer yields and was an order of magnitude higher for potassium acrylate than for the sodium or the lithium salt. Sodium methacrylate was more reactive than potassium metbacrylate; the lithium salt of methacrylic acid was entirely inert. The sodiuni methacrylate polymerization had an initial accelerating phase. Studies of x-ray diffractlon of the polymerizing potassium ucrylate showed only minor changes in tbe diffraction pattern of the monomer, with the size of the unit cell remaining almost unchanged. Poly(potassium acrylate) produced in the solid state showed four diffuse diffraction rings whicb were not observed in samples prepared from poly'(acrylic acid) obtained by polymerizing a benzene solution of tbe monomer. While the x- ray data indicated the existence of a separate polymer phase in tbe polymerizing salts, tbe pronounced difference in tbe characteristics of the polymerization process of different salts of the same monomeric anion pointed to a control of the reaction by the geometry of the crystal lattice. The evidence suggests that the polymer lies in an amorpbous phase but that the reactive ends of growing chains are anchored in the monomer lattice. Electron spin rescnance spectra are similar for irradiated potassium acrylate and sodium methacrylate, but the potassium acrylate spectrum changes gradually froin a tbree peak to a single peak structure when tbe sample is heated to 100 deg C, wbile the other two salts have spectra which are not affected by a similar beating cycle. The absence of the characteristic ESR spectrum of polymethacrylatc radicals in irradiated sodium methacrylate suggests that under the experimental conditions used few of the primary radicals were able to initiate cbains.A five-peak ESR spectrum was observed in irradiated sodium acrylate. (auth)
- Research Organization:
- Brooklyn. Polytechnic Inst. Polymer Research Inst.
- NSA Number:
- NSA-16-001809
- OSTI ID:
- 4833681
- Report Number(s):
- TID-14086
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALKALI METALS
AMORPHOUS STATE
ANIONS
BENZENE
CHEMICAL REACTIONS
CHEMISTRY
CRYSTALS
DECAY
DIAGRAMS
DIFFRACTION
EFFICIENCY
ELECTRONS
GAMMA RADIATION
IRRADIATION
LATTICES
LITHIUM COMPOUNDS
LOW TEMPERATURE
MATHEMATICS
METHACRYLATES
METHACRYLIC ACID
NUCLEAR MAGNETIC RESONANCE
ORE PROCESSING
POLYMERIZATION
POLYMERS
POTASSIUM COMPOUNDS
REACTION KINETICS
RESONANCE
SALTS
SAMPLING
SODIUM COMPOUNDS
SOLUTIONS
SPECTRA
SPIN
TESTING
URANIUM ORES
VACUUM
VELOCITY
X RADIATION