Electrochemical reduction of an exemplary ATRP catalyst, C 11 Br 2 /Me 6 TREN, is shown to be an efficient process to mediate and execute an ATRP. The onset of polymerization occurs only through passage of a cathodic current achieved under a reductive potential to form Cu 1 Br 2 /Me 6 TREN, within the reaction medium. Unprecedented control over the polymerization kinetics can be attained through electrochemical methods by modulating the magnitude of the applied potential allowing polymerization rate enhancement or retardation. Additional polymerization control is gained through electrochemical “dials” allowing polymerization rate enhancements achieved by larger applied potentials and the ability to successfully switch a polymerization “on” and “off between dormant and active states by application of multistep intermittent potentials.

https://science.sciencemag.org/content/sci/332/6025/81.full.pdf

Electrochemically mediated atom transfer radical polymerization

The invention concerns a process for the preparation of a hardening accelerator composition by reaction of a water-soluble calcium compound with a water-soluble silicate compound and a process for the preparation of a hardening accelerator composition by reaction of a calcium compound with a silicon dioxide containing component under alkaline conditions, in both cases the reaction of the water-soluble calcium compound with the water-soluble silicate compound being carried out in the presence of an aqueous solution which contains a water-soluble comb polymer suitable as a plasticizer for hydraulic binders. The invention concerns also a composition of calcium silicate hydrate and comb polymer, its use as hardening accelerator and for the reduction of the permeability of hardened compositions.

Plasticizer-Containing Hardening Accelerator Composition

We present an in-depth study of the formation of stable suspensions of low density aggregates of calcium silicate hydrate (C–S–H) particles stabilized by comb-like copolymers. These suspensions exhibit fundamentally interesting properties such as gel formation at 1.4 vol% of particles. Furthermore, they constitute a novel class of hardening accelerators for cementitious systems. Stabilization of C–S–H particles by polyelectrolytes is essential for the synthesis of stable and active C–S–H suspensions. Comb-polymers consisting of charged monomers (acrylic acid or 2-(phosphonooxy)-ethyl-methacrylate) and poly(ethylene glycol) monomers direct C–S–H particle aggregation into fractal structures. The fractal nature of the aggregates has been characterized by TEM and SAXS. Based upon (U)SAXS data of different C–S–H suspensions, it is demonstrated that two-dimensional initial C–S–H particle aggregation favours the creation of structures with a high specific surface area which are particularly active as cement hardening accelerators.

/pdf/oriented-aggregation-of-calcium-silicate-hydrate-platelets-2x2re9jmr1.pdf

Oriented aggregation of calcium silicate hydrate platelets by the use of comb-like copolymers

Claimed is a formulation containing a) at least one component having dispersing properties and being selected from branched comb polymers having polyether side chains, a naphthalene sulphonate-formaldehyde condensate and a melamine sulphonate-formaldehyde condensate, and b) a polycondensation product. Typical representatives of component a) are polycarboxylate ether, polycarboxylate ester and uncharged copolymers. In addition to the main components a) and b) further additives such as anti-forming agents and tensides or polymers having a low Charge, neutral polymers or polyvinyl alcohol can be comprised by the formulation that is suitable for Controlling the flowability of aqueous suspensions of construction Chemicals.

Formulation and its use

Process for the production of paper, board and cardboard having high dry strength by addition of an aqueous composition comprising a nanocellulose and at least one polymer selected from the group consisting of the anionic polymers and water-soluble cationic polymers, draining of the paper stock and drying of the paper products.

Method for producing paper, paperboard and cardboard having high dry strength

Disclosed is a polycondensation product comprising A) an aromatic or heteroaromatic compound containing 5 to 10 C atoms or heteroatoms, said compound being provided with an average of 1 to 300 oxyethylene groups and/or oxypropylene groups per molecule which are linked to the aromatic or heteroaromatic compound via an O atom or N atom, and optionally B) an aromatic compound selected among the group comprising phenols, phenol ether, naphthols, naphthol ether, anilines, furfuryl alcohols, and/or an aminoplast former selected among the group comprising melamine (derivatives), urea (derivatives), and carboxylic acid amides, and C) an aldehyde selected among the group comprising formaldehyde, glyoxylic acid, and benzaldehyde or mixtures thereof, the benzaldehyde optionally containing acid groups in the form of COOMa, SO3Ma, and PO3Ma, wherein M = H, akali metal or alkaline earth metal, ammonium, or organic amine radicals and a = 1/2, 1, or 2. Surprisingly, the inventive polycondensation product causes very good liquefaction of hydraulic binding agents, e.g. cement, resulting in substantially improved liquefaction of the construction material at a lower dose while pourability can be maintained over a longer period of time as opposed to naphthalene sulfonates or melamine sulfonates.

Polycondensation product based on aromatic or heteroaromatic compounds, method for the production thereof, and use thereof

The invention relates to a phosphate polycondensation product which can be used as flow promoter for hydraulic binders and which contains a structural element (I) having an aromatic or heteroaromatic and one polyether side-chain, a phosphate structural element (II) having an aromatic or heteroaromatic and a structural element (III) having an aromatic or heteroaromatic, wherein structural element (II) and structural element (III) differ exclusively in that the OP(OH)2-group of structural element (II) is replaced by H in structural element (III) and structural element (III) is not the same as structural element (I).

Phosphated polycondensation product, method for production and use thereof

Copolymers which are obtained by free radical copolymerization of a vinylic poly(alkylene oxide) compound (A) with an ethylenically unsaturated monomer compound (B), and the use thereof as dispersants for aqueous solid suspensions, in particular hydraulic binders based on cement, lime, gypsum and anhydrite, are described. With very good water reduction power, the copolymers according to the invention scarcely retard the hardening of the concrete and ensure long processability of the concrete.

Phosphorus-containing copolymers, method for the production thereof, and use thereof

Pulverulent polycondensation products are described, comprising a) from 5 to 95% by weight of a polycondensation product based on an aromatic or heteroaromatic compound (A) having from 5 to 10 carbon atoms or hetero­atoms having at least one oxyethylene or oxypropylene radical and an aldehyde (C) selected from the group of formaldehyde, glyoxylic acid and benzaldehyde or mixtures thereof, and b) from 5 to 95% by weight of a finely divided mineral support material having a specific surface area of from 0.5 to 500 m2/g (according to BET to DIN 66 131). The inventive pulverulent polycondensation products are outstandingly suitable in building material mixtures in an amount of from 0.1 to 5% by weight, based on the weight of the building material. The pulverulent polycondensation products have a number of advantages in this context, for example excellent storage stability, good liquefying action at low dosage and technically simple production.

Alexander Kraus

Papers

Polycondensation product based on aromatic or heteroaromatic compounds, method for the production thereof, and use thereof

Formulation and its use

Phosphated polycondensation product, method for production and use thereof

Phosphorus-containing copolymers, method for the production thereof, and use thereof

Pulverulent polycondensation products