Poly(N‐aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. These include N‐(2‐fluoro phenyl), N‐(3‐fluoro phenyl), N‐(4‐fluoro phenyl), N‐(2,4‐difluoro phenyl), N‐(2,5‐difluoro phenyl), N‐(2,3,5,6‐tetrafluoro phenyl), and N‐(pentafluoro phenyl). The polymerization of N‐(fluoro phenyl) maleimides by free‐radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by γ‐ray irradiation with that by free‐radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x‐ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free‐radical polymerization initiated by AIBN in bulk or in solution and by the self‐initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly[N‐(fluoro phenyl) maleimide]s have been analyzed by using a multiple‐heating‐rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. On the basis of the comparison between the overall activation energy of the thermal degradation of poly[N‐(fluoro phenyl) maleimide]s and NMR spectra of their corresponding monomers, it can be concluded that the 1H shifts due to ethylenic protons are so characteristic in sign and magnitude as to be useful in thermal stability elucidation. Some qualitative explanations were given on the stability of these polymers as affected by the type and size of the substituent. The x‐ray diffractograms of all samples show two rather broad peaks indicative of noncrystalline structures. The location of the peaks does not depend upon preparation conditions and temperature. Poly(N‐maleimide)s of fluoroanilines have not been hitherto described.

A series of nine poly(N-n-alkylma1eimide)s (PMIs) with the n-alkyl side chain ranging in length from ethyl to octadecyl and including only the even members of the series was studied by differential scanning calorimetry (DSC) from 100 K to above the glass transition temperature. The nine members of the PMI series generally were found to exhibit a glass transition temperature (Tg), a sub-glass transition temperature (sub-T, = Ty), and, but only the four higher homologs a melting point (T,) with the respective melting enthalpy (AHf). The glass transition of the amorphous members is directly related to the number of methylene groups (including terminal methyl) of the n-alkyl side chain of the repeating unit. The values of T, estimated according to a semi-empirical equation are in good agreement with the experimental data. The melting points of the members of the series presenting crystallinity in the n-alkyl side chain were analyzed. A good fit of a Garner plot by a least-mean-squares procedure is obtained with = 408,O K, a = -6,26 and b = -2,03. The contribution to the heat of melting per methylene unit clearly demonstrates that the hexagonal paraffin crystal structure is present in the crystalline members, in agreement with X-ray data. The data when analyzed by Jordan's procedure show that only part of the n-alkyl side chain is forming a crystal lattice.

The glass transition temperatures (T,s) of a series of poly N-(n-alkyl) maleimides covering only the even members with side chains ranging in length from ethyl to n-octadecyl have been studied from room temperature to above T,. T,s and thermal quantities have been determined from the specific volume-temperature relations only for the higher (n = 8, 10, 12, 14, 16 and 18, where n = n o of CH2) members of the series. However for the lower ones (n = 2 , 4 , 6 , 8 and 10) T,s have been detected from heat capacitytemperature traces of differential scanning calorimetry diagrams by extrapolation to zero rate of heating. Accurate consistency was found in the values (n = 8 and 10) determined by both experimental methods. T,s of these polymers continuously decrease as the number of methylene groups in the side chain is increased, and they have been correlated with the size of the n-alkyl group in the side chain. The results are in accord with a previously studied series concerning the effect of a long side chain on the T, of a comb-like polymer in the amorphous state. T,s of poly N-(n-alkyl) maleimides encompassing a wide range of methylene group content (n = 2 , 4 , 6 , 8 , 10 and 12) have been examined according to the Gordon-Taylor-Wood extrapolation with the objective of ascertaining the T, of polyethylene (PE). Our approach of ignoring higher members of the homologous series in this extrapolation appears to be old and well known and it has been variously ascribed to d i f p n t authors. Extrapolation of T, values t o 100% amorphous PE gives a T, of 200 f 10 K in complete agreement with recent predictions made by Boyer from different sources of data.The Simha-Boyer free volume quantity Au . T, decreases slowly with the methylene group content in the longer terms (n = 8, 10, 12, 14, 16 and 18) of the series presumably because of a reduction in the polarity or an in-chain crankshaft loss mechanism which generates free volume in the glassy state, as stated by Boyer. T,s do not correlate very well with the contributions of the atomic groups to the cohesive energy density (c.e.d.) so it can be concluded that c.e.d. is not the only factor determining T,. However, a somewhat improved relationship might be obtained by taking into account the steric hindrance effect according to an approach made by Hayes.

This work deals with some features of the reaction of organic acid chlorides with poly(viny1 alcohol). The structure of the modified polymers was determined by means of IR, UV and NMR spectroscopy as well as by chemical analysis. Vinyl alcohol-vinyl butyrate copolymers were obtained by reaction of poly(viny1 alcohol) with n-butyryl chloride without any catalyst. The reaction appeared to satisfy a second order kinetics for conversions no higher than 50%. The activation energy found was of 9.9 kcal/mol. The use of pyridine as a catalyst involved a noticeable increase of the reaction rate, but this effect was found to be independent of the acid chloride used. When triethylamine was used as a catalyst, b-keto ester groups were found t o be grafted onto the polymer chain. The steric hindrance of these groups were thought to be sufficiently important for the conversion to reach a limit of about 30%. The observed swelling in water of vinyl alcohol-vinyl butyrate copolymers made it reasonable to conclude that the hydrophilic character of the copolymers decreased progressively when the ester group content increased. ZUSAMMENFASSUNG:Die Reaktion von Carbonsiurechloriden mit Polyvinylalkohol wurde untersucht. Die Struktur der modifizierten Polymeren wurde durch IR-, UV-, NMR-Spektroskopie und chemische Analysen bestimmt. Durch die Reaktion des Polyvinylalkohols mit n-ButtersPurechloride entstehen Vinylalkohol-Vinylbutyrat-Copolymere. Wenn der Umsatz dieser Reaktion kleiner als 50% ist, findet man eine Kinetik zweiter Ordnung mit einer Aktivierungsenergie von 9.9 kcal/mol. Wenn Pyridin als Katalysator venvendet wird. nimmt die Reaktionsgeschwindigkeit bemerkenswert zu, unabhhgig von dem verwendeten Siurechlorid. Wenn man Triithylamin als Katalysator verwendet, dann erscheinen aufgepfropfte P-Ketoester-Gruppen in den Polymerketten. Wegen der sterischen Hinderung dieser Nebengruppen wird der Umsatz nicht hOher als 30%. Je grOkr der Gehalt an Estergruppen ist, um so weniger hydrophil ist das Polymere, wie durch Quellungsmessungen der Vinylalkohol-Vinylbutyrat-Copolymeren in Wasser festgestellt wurde.

This work deals with the modification reaction of dextran with ethyl and butyl chloroformate using tertiary amines as catalyst/acceptor systems and the DMF/LiCl system as solvent. The structure of the resulting polymers was determined by means of IR, 'H and "C NMR spectroscopy as well as by chemical analyses. The reaction rate was found to'increase in the following order: N,N'-dimethylaniline < pyridine < triethylamine. The presence of cyclic carbonates was observed when triethylamine was used as catalyst. A linear dependence of the reaction rate on polymer and pyridine concentrations and a more complex dependence on the n-alkyl chloroformate concentration were found. Reaction rate and yield decrease with increasing amount of LiCl in the solvent medium and increase with increasing chain length of the n-alkyl chloroformate. The activation energy was found to be 64 kJ/mol (15,3 kcal/mol). The equilibrium water content (EWC) values decreases progressively when either the content of carbonate groups or the side chain length increases. The hydrolysis in the heterogeneous phase showed that the time required for the polymer solubilization is dependent upon the nature of the carbonate groups, the temperature as well as the pH value of the medium. Dextranase was found to be inactive in the hydrolysis of water-insoluble modified dextrans. However, the hydrolysis takes place when water-soluble modified dextrans were used. a) Part I: ~f .~) .