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Polycarboxylic ethers or polycarboxylate (PCEs) are one of the most employed superplasticizers in construction. However, the understanding of their microstructure–property relationship is still incomplete. Recently, a theoretical model was proposed that relates the microstructure–conformation of the PCE to its effect on the adsorption onto cement particles and cement hydration time. In this work, the effects of a wide range of PCEs with different side chain lengths (P = 5, Group 1; P = 20, Group 2; and P = 45 and 113, Group 3) having flexible backbone worm conformation except one which has stretch backbone worm conformation (P = 113) were experimentally investigated for their effect on adsorption and cement hydration. It is found that PCEs from Group 1 show electrostatic repulsion as dispersing mechanism, unlike PCEs from Groups 2 and 3. Furthermore, the prediction of the theoretical model is also assessed for all the studied PCEs. Only Group 1 PCEs (shortest side chains) showed deviation from the theoretical predictions, and it was attributed to their different behaviors from the standard PCEs for which the theoretical model was developed.

Methacrylic acid-co-poly(ethylene glycol methacrylate) (MAA-co-PEGMA) copolymers (MPEG-type polycarboxylate ether (PCE) superplasticizers) are characterized by a comb-like structure. Although they have been used for years as dispersants in cementitious formulations, their structure–property relationship is still not fully understood. In this work, PCEs with uniform composition and different charge-density (N) or different side chain lengths (P) are synthesized by free-radical copolymerization varying the MAA/PEGMA ratios and ethylene oxide units in the PEGMA macromonomers. The effect of these copolymers on the hydration kinetics of an Ordinary Portland Cement (OPC) is analyzed, and it is observed that by increasing the PCE concentration the hydration is delayed. For a given PCE concentration, the delay is longer as the MAA/PEGMA ratio increases or the side chain length of the PEGMA decreases. The hydration delay is proportional to the carboxylate dosage and all PCEs fit in a master curve proving that the microstructure of the PCEs synthesized by free-radical copolymerization can be correlated with the hydration delay of a commercial OPC.

Water-soluble copolymers of methacrylic acid and poly(ethylene glycol) methacrylate (poly(MAA-co-PEGMA)) present a comb like structure. These macromolecules under alkaline conditions present an anionic backbone and uncharged side chains. The control of their microstructure is of paramount importance for application as cementitious admixtures. With this in mind, open-loop control strategies including monomer starved and optimal addition policies were employed to obtain homogeneous composition copolymers. A detailed mathematical model was developed for the copolymerization of MAA and PEGMA5 and was used to develop optimal feeding strategies. The mathematical model provides a good representation of the experimental data sets and copolymers with desired homogeneous copolymer compositions were synthesized within the shortest possible reaction times.

Microwave (MW) irradiation has arisen as a more sustainable alternative to conventional heating (CH) for chemical reactions because it provides non-contact, volumetric equal and fast heating. However, in free-radical polymerization, the MW effect is still quite controversial, probably due to the lack of reliable, comparable experimental data of both CH and MW assisted polymerization processes. In this work, taking advantage of technically superior MW reactor design, similar temperature profiles and conditions of CH and MW assisted polymerization reactions were enabled. Copolymerization of various monomer couples with different polarity and dielectric properties was studied in solution of different organic solvents in the presence of different initiators. As a result, it was concluded that the interaction of the reaction components with the MW irradiation is essential and will determine if any effect of MW irradiation on the reaction and products occurs. On the contrary to some reported studies, for the typical monomers used in free radical polymerization studied here (acrylates, methacrylates, styrene) no difference in reaction rates, copolymer composition and properties were observed between the MWH and CH processes, independently of the solvent and initiator used. However, in the case of the presence of an organometallic monomer within the monomer couple, an observable reaction rate enhancement was obtained under MW irradiation, along with changes in the reactivity ratios and differences in the copolymer composition. This effect is considered a specific microwave effect, for the first time demonstrated in free-radical solution polymerization process and was explained by the principles of selective heating of the organometallic reaction components in solution.

Methacrylic acid‐co‐polyethylene glycol methacrylate (MAA‐co‐PEGMA) copolymers (also known as MPEG‐type polycarboxylate ether (PCE) superplasticizers) present comb‐shaped microstructure and they are generally used as dispersants of inorganic particles in cementitious formulations. Application properties of the PCEs strongly depend on the molecular structure and therefore accurate characterization of the microstructure is necessary to fully understand the structure–property relationship. In this work, MAA‐co‐PEGMA copolymers with various lateral size chain lengths and homogeneous copolymer compositions are synthesized by starved‐feed semibatch copolymerization. Molar mass and radius of gyration distributions and monomer sequence distribution are measured using size exclusion chromatography coupled with multi angle light scattering (SEC/MALS/refractive index, RI) and 1H and 13C NMR, respectively. Furthermore, it is proved that the experimental radius of gyration compares well with the prediction of a theoretical model for the radius of gyration that uses characteristic parameters of the microstructure of the PCEs (e.g., average molar masses). This confirms the accuracy of the measurements of the absolute molar masses for the MPEG‐type PCEs synthesized by free‐radical (co)polymerization.