It is shown that the block-like structure of the polyampholyte polfimethacrylic acid)block-poly( 1-methyl4vinylpyridinium chloride) considerably influences its conformational behaviour. This specific behaviour is explained by the formation of intra-macromolecular polyelectrolyte complexes stabilized by cooperative ionic contacts between acidic and basic units near the isoelectrlc point (i.e.p.). The structure of the block-polyampholyte at the i.e.p. is suggested to be close to the structure of non-stoichiometric polyelectrolyte complexes. The complex formation ability of the block-polyampholyte with respect to anionic, cationic, and nonionic polymers is also studied. By means of potentiometric, conductometric, and viscometnc methods the composition of interpolymer complexes is determined and the degree of conversion in complex formation reactions is calculated. The water solubility (or insolubility) of interpolymer complexes is determined by the length of acid or basic blocks. It is proposed that a dissociation of interpolymer complexes into their individual components takes place at the i. e. p. of the blockpolyampholyte.

Recentlywe investigated the inter-polyelectrolyte reactions of poly(methacry1ic acid)-block-poly(l-methyl-4-vinylpyridinium chloride) with respect to anionic, cationic and non-ionic polymers. The complexation reactions of a block-polyampholyte with surfactants and dye molecules were also considered ').In the present communication the intra-and interpolyelectrolyte reactions of a nearly equimolar block-polyampholyte poly(methacry1ic acid)-block-poly(1-methyl-4-vinylpyridinium chloride) (1) are studied.

It is well-known that polyelectrolytes interact with various low-and highmolecular-weight substances and form interpolyelectrolyte complexes (PEC) which usually precipitate from aqueous solution The preparation of thin films or membranes from PEC is a multistage process and includes the separation of the precipitate, its dissolution in a ternary mixture consisting of water, organic solvents and neutral salts, casting, removal of solvents and sometimes thermal treatment of the films 5 -8 ) . Polymer-surfactant composite films were prepared by casting the solution of polycomplexes in common halogenated organic solvents g). By means of differential scanning calorimetry (DSC) and electron paramagnetic resonance (EPR) it was shown that the films are composed of lipid multilamellae in which lipids aggregate in a manner similar to lipid bilayers.Reactions in which polyelectrolyte complexes are formed and which proceed on a dimeric interface represent a new method for the synthesis of various types of membranes and thin films and so far have not yet been considered. In the present communication the results of complex formation on a dimeric interface between poly(2-vinylpyridine) (P2VP) and sodium polystyrenesulfonatea) (PSS), sodium dodecylsulfonate (SDS), metal salts are discussed. Experimental partPoly-2-vinylpyridine (weight-average molecular weight a,-= 3,4 . lo') and sodium polystyrenesulfonate (poly[sodium 1 -(4-~ulfonatophenyl)ethylene] (M, = 3 . lo' ) were purchased from "Polyscience" (USA) and used without purification. Reagent-grade sodium dodecylsulfonate (SDS), LiCIO,, LiJ, AgNO, and Cu(NO,), 6H,O were used. Potentiometric and conductometric titrations were carried out on the digital pH-meter OP-211/1 and conductometer OK-102/1 (Hungary) at room temperature. Complex-forming reactions on the dimeric interface were performed as follows:To the aqueous solution of the water-soluble component the benzene solution of poly(2-vinylpyridine) was added gradually at constant stirring with 200 r.p.m. so that the surface of the aqueous solution was fully covered by the organic solution. The formation of thin films or membranes occurs immediately. The thickness of the films depends on the concentration of the a) Systematic IUPAC name: poly[sodiurn 1 -(4-sulfonatophenyl)ethylene].

SUMMARY:The swelling behaviour of a non-ionic poly(N-vinyl-2-pyrrolidone) hydrogel in a linear poly-(acrylic acid) solution upon the influence of chain length, pH, ionic strength, and water/dimethyl sulfoxide composition was studied. The sharp shrinkage of the gel volume within a narrow range of polyacid concentration takes place as a result of the formation of an intermacromolecular gel-polymer complex on the base of hydrogen bonding. According to X-ray diffraction this complex is amorphous. The formation of the gel-polymer complex is a long term process and the system reaches equilibrium within 48 h. The swelling behaviour strongly depends on the chain length of the polyacid whereas it does not depend on the ionic strength. With increasing pH value and changing water/dimethyl sulfoxide composition the gel reswelling is induced. The complex formation with poly(acrylic acid) occurs in the same way for linear and crosslinked poly(N-vinyl-2-pyrrolidone).

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