No abstract

SynopsisThe chemical reaction in aqueous medium of polyacrylonitrile and acrylonitrile-vinyl acetate copolymer using asymmetrical diamines of H2N-(CH2),-NR2 ( m = 2,3) structure was studied. It was found that the nitrile group is modified to an dialkylaminoalkylacrylamide group; also determined were the reaction conditions required to obtain the highest degree of chemical transformation of the nitrile groups. All modified compounds were characterized by analytical spectroscopy (IR and 'H NMR) and by rheological methods. It was also established that glutaronitrile can be used as a low-molecular-weight model to study the chemical transformation of nitrile groups in polyacrylonitrile and related polymers. P-, and y-dinitriles only, where there exists the possibility of a ring-shaped intermediate.7 However, the uncatalyzed reaction also occurs for other nitrile compounds if the nitrile group is activated by certain functional groups.s Also reported is the reaction of PAN with diamines of H2N-(CH2)m-NH2 ( m = 2,3) structure, which leads to poly(viny1amidines) when performed with a catalyst in anhydrous media.g This paper described the reaction in water of PAN and its copolymers with asymmetrical diamines of H2N-(CH2),-NR2 ( m = 2,3) structure. The reaction takes place without a catalyst, perhaps because of the appearance of imide rings during intermediate reaction steps. The macromolecular compounds DRAGAN ET AL studied were PAN and a technical acrylonitrile (9&95%)-vinyl acetate (510%) copolymer (AN-VAc), as fibers.Chemical reactions were investigated in the absence of organic solvents, at atmospheric pressure. EXPERIMENTALThe acrylonitrile was previously distilled. PAN was prepared by polymerization in water using a redox K$320s/K&05 initiator system at 60°C. The polymerization time was about 70 min. Polymer was poured into eight volumes of hot water, then it was filtrated and the precipitate washed with hot water and methanol.The polymer was dried, dissolved into N,N-dimethylformamide, and precipitated in methanol. The average molecular weight was viscosimetrically measured in DMF at 25OC, using the equationlo [q] = 2.43 x 10-4 x Z;0.75 PAN, prepared by us, was of M , = 100,400. AN-VAc fibers were washed with methanol, dried, and cut in small pieces (2-3 cm).

The reaction of chloromethylated polystyrene with tris(2‐hydroxyethyl)amine in N,N‐dimethylformamide is described for the conditions to prepare soluble reaction products. The groups of the quaternary ammonium salt, which appear in the first stage of the reaction, transpose to the amino‐ether groups. The reaction was followed by elementary analysis, IR and 1H‐NMR spectra, and viscosimetric measurements for nondialyzed and dialyzed samples. The presence of the tertiary amine groups on obtained polymers was also shown by titration. The polymers from the reaction of chloromethylated polystyrene with tris(2‐hydroxyethyl)amine reacted easily with benzyl chloride.

Samples of styrene/divinylbenzene/acrylonitrile macroporous copolymers were prepared, using polystyrene as inert medium. The initial viscosity average molecular weight of the polystyrene samples were:Mv ,= 87000, 98000, 117000 and 218000. The polystyrene samples with the initial molecular weights Uv, = 87000 and Rv., = 117000 were reused as inert media, for many times, until they lost their capacity to produce permanent porosity of the copolymers. The macroporous copolymers were characterized by their permanent porosity and volume swelling. If a polystyrene sample is used for many times, the molecular weight of the polystyrene removed (extracted) is gradually diminished and therefore the permanent porosity of the macroporous copolymers decreases step by step. The reasons responsible for this behaviour are:during the copolymerization process a polystyrene with a smaller molecular weight is formed, -polystyrene parts of high molecular weights are included in the network structure of the macroporous co-The evidence for this was given by plotting the differential and integral molecular weight distribution curves polymers.for six samples of polystyrene.(mv) of PS is higher than 50 000 the copolymers formed possess a permanent porosity. Their characteristics (pore volume, pore radius) are dependent on the concentration and mv of PS introduced into the monomer mixture. Unlike the low molecular weight inert media during the copolymerization process, PS undergoes alterations of its polydispersion. This is reflected first of all by the decrease of the molecular weight (Hv) of extracted PS4.5).For the purpose ofestablishing the conditions to reuse extracted PS as diluent in the synthesis of the permanent porous copolymers, the causes that led to the molecular weight decrease of extracted PS in correlation with the molecular weight of initial PS (=",,) were studied. Experimental PartFreshly distilled styrene, technical divinylbenzene (57% by weight divinylbenzene) and acrylonitrile were used as monomers. The copolymerization reaction was initiated by benzoyl peroxide (1.0% by weight referred

SynopsisSeveral macroporous styrene-divinylbenzene copolymers were prepared using different diluents. The copolymers were chloromethylated with monochlor methyl ether and aminated with N,Ndimethyl-2-hydroxyethylamine in order to perform strongly basic anion exchanger, type 11. It was established that the network morphology of anion exchanger determines its ion-exchange rate. It was, also established, by means of transmission electron microscopy, that chloromethylation reaction led to the morphological changes in the macromolecular network of the copolymers.