A method of preparing a stable dispersion in an aqueous medium of particles of polymer in which stabilisation of the particles against flocculation is effected by a steric mechanism. The method comprises (i) forming a sterically stabilized dispersion in a non-aqueous liquid of a first polymer insoluble in the non-aqueous liquid and in water; (ii) polymerizing monomer in the same non-aqueous liquid in the presence of the particles of the first polymer and of a steric stabilizer, so as to form a second polymer which is soluble in the chosen aqueous medium; (iii) transferring the resulting particles to the aqueous medium. There may be prepared in this way aqueous dispersions of polymers incorporating units of water-soluble monomers, which are diffiult to make by known aqueous emulsion polymerization techniques.

A fluidized flocculant being a dispersion of from about 5 to 60 weight percent of finely ground polyacrylamides in a fluid, water soluble polyhydric alcohol carrier. The fluidized flocculant is prepared as a dispersion having a particle size of less than 75 microns and can be metered and pumped into a water stream and mixed therewith to form a flocculant solution that can be readily metered and pumped into water to be clarified.

A solid-phase method for the synthesis of N-substituted oligomers, such as poly (N-substituted glycines) (referred to herein as poly NSGs) is used to obtain oligomers, such as poly NSGs of potential therapeutic interest which poly NSGs can have a wide variety of side-chain substituents. Each N-substituted glycine monomer is assembled from two "sub-monomers" directly on the solid support. Each cycle of monomer addition consists of two steps: (1) acylation of a secondary amine bound to the support with an acylating agent comprising a leaving group capable of nucleophilic is displacement by --NH.sub.2, such as a haloacetic acid, and (2) introduction of the side-chain by nucleophilic displacement of the leaving group, such as halogen (as a resin-bound .alpha.-haloacetamide) with a sufficient amount of a second sub-monomer comprising an --NH.sub.2 group, such as a primary amine, alkoxyamine, semicarbazide, acyl hydrazide, carbazate or the like. Repetition of the two step cycle of acylation and displacement gives the desired oligomers. The efficient synthesis of a wide variety of oligomeric NSGs using automated synthesis technology of the present method makes these oligomers attractive candidates for the generation and rapid screening of diverse peptidomimetic libraries. The oligomers of the invention, such as N-substituted glycines (i.e. poly NSGs) disclosed here provide a new class of peptide-like compounds not found in nature, but which are synthetically accessible and have been shown to possess significant biological activity and proteolytic stability.

Coating compositions containing copolymers of ethylenically unsaturated aromatic monomers and ethylenically unsaturated nitrile monomers are useful for coating paper, plastics, metals and other packaging materials. These compositions, when blended with vinyl polymers, show improved flexibility and adhesion.

Stable dispersions of halogen-containing addition polymers, such as polyvinylidene fluoride, in water-dilutable liquid media, for example 2-butoxyethanol, are produced by dispersing pre-formed particles of the polymer, of a number-average size in the range 0.1-10 microns, in the liquid medium in the presence of a polymeric dispersant containing in the molecule a hydrophobic polymer chain and strongly ionized groups, in particular quaternary ammonium groups, the strongly ionized groups being present in such a proportion as to provide a charge density of from 0.05 to 6.0 milliequivalents per gram of the total dispersant. The dispersions thus obtained are valuable as a basis for water-borne coating compositions.