Molecular weight distribution and average molecular weight of polymers obtained by radiation induced solid state polymerization were calculated.
In the calculation, effective monomer concentration was introduced, and the annealing of crystal monomers during polymerization has been taken into consideration.
In overall differential molecular weight distribution, it was shown that there appear two peaks in the distribution curve only when the chain transfer coefficient and the monomolecular termination coefficient are in a limited range. On the other hand, it was also shown that the shape of lower peak is much influenced by the nucleation phenomenon. Then, the average molecular weight was calculated on the basis of these molecular weight distribution functions, as a function of polymerization period for both post and in-source polymerizations. Although the results of the calculation agree well with the reported experimental results qualitatively, it is difficult to discuss it quantitatively, since the average molecular weight is less influenced by the various parameters.

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The homopolymerizations of N-(4-substituted phenyl) maleimides, _??_(X: OCH₃, CH₃, H, Cl, OCOCH₃, COOC₂H₅, COCH₃) were carried out with azobisisobutyronitrile as an initiator in dimethylformamide.
In the equation which expresses the initial rate of polymerization,
R_p=k[AIBN]^x[M]^v
the values of x and y were found to be in the range of 0.6-0.9 and 1.0-1.5, respectively, according to the monomer. Also the over-all activation energies and the frequency factors were measured to be 23.8-29.1 kcal/mole and 6.6×10¹³-6.6×10¹⁷.
The relationship between logarithm of initial rate of polymerization (R_p) and σ of Hammett's equation did not give a straight line, the initial rates being greater than expected from the equation for electron releasing substituents and smaller for electron attracting substituents. The above curve was converted to a straight line by applying the Yamamoto- Otsu's equation, which contains a correcting term concerning resonance effects as compared with Hammett's equation. Thus the relationships between the reactivities of N-(4-substituted phenyl) maleimides in the copolymerization with vinyl acetate or methyl methacrylate and those in the homopolymerizations were explained.
The anionic polymerizations of the above monomers were carried out with n-BuLi or C₂H₅ONa as initiator in tetrahydrofuran. With n-BuLi initiator the polymeryield was high but the reduced viscosity was found to be about 0.07 which corresponded to oligomers.

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Three maleimide derivatives which were characterized by the presence of hydroxyl radical in N-substituent, i. e. N-4-Hydroxyphenyl maleimide (HPMI), N-2-Hydroxyethyl maleimide (HEMI) and N-Methylol maleimide (MMI) were synthesized. Their polymerizations, 1) initiated with potassium persulphate in water or water-dioxane mixture solution, 2) initiated with azobisisobutyronitrile in dimethylformamide solution, and 3) initiated with n-butyllithium in tetrahydrofuran solution were studied. In 1), the relatively low conversion and the presence of maximum conversion in the polymerization curve were ascribed to the properties of initiator. In 2) the square root law of the polymerization did not hold for any monomer. The rate of polymerization of HPMI was the highest but the reduced viscosity of the polymer decreased with increase in the conversion. These phenomena were explained by the high activity of hydroxyl group in HPMI monomer. In 3) some oligomers containing a trace of lithium were obtained and it was ascertained that the hydroxyl group in the monomers did not entirely stop the anionic polymerization. The acetalizing reaction of HEMI polymer with formaldehyde and the adsorption of iodine by the acetalized polymer were briefly examined.

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Methyl methacrylate (MMA) was polymerized by n-butyllithium in toluene solution at -50, -30, 0, and 30°C. A kinetic treatment concerning the effect of the polymerization conditions on the molecular weight of polymer showed that the monomer transfer reaction existed in the present systems, and the monomer transfer constant ratio (k₄/k₂) was evaluated. The addition of methyl propionate lowered the molecular weight of polymer, and the ester transfer constant ratio (k₅/k₂) was determined. k₄/k₂ was very close to k₅/k₂. Similar experiments were carried out with n-butyl methacrylate, and similar results as for MMA were obtained. The present investigation established that the molecular weight of the polymer is controlled by the monomer transfer reaction, and suggested that the mechanism of monomer transfer reaction is an interaction between the growing anion and the ester group of monomer.

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The average distribution of carboxyl groups within ethyl acrylate-acrylic acid copolymer latex particles was measured. The latex particles were stepwise dissolved from their surfaces toward the center by adding increment of alkaline solution. The dissolved polymer hereby was separated by a high speed centrifuge, and then the carboxyl group content of the polymer was determined. The result showed that the concentration of carboxyl groups was approximately 2-3 times higher at particle surface than average value and the concentration decreased rapidly toward the inside, in good agreement with the distribution infered from the properties of carboxylated polymer latices.

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The distribution of carboxyl group within poly (ethyl acrylate) latex particles car boxylated with two different series of unsaturated acid monomers, α-alkyl substituted acrylic acid and monoalkyl itaconates was determined. Furthermore, the partition coefficients between monomer and aqueous phase and the copolymerization rates of the unsaturated acid monomers were determined, and an attempt was made to relate the results to relate to the carboxyl group distribution data. It was found that the homogeneity of carboxyl group distribution was improved in accordance with the increasing tendency of the partition coefficient caused by the increase of the length of substituted alkyl chain in the unsaturated acid monomer. On the other hand, the copolymerization rate of the unsaturated acid monomer could not be related to the carboxyl group distribution state.

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