The diacetone acrylamide crosslinking reaction and its control of core‐shell polyacrylate latices at ambient temperature

Abstract

Self crosslinkable core-shell polyacrylate latices (PAs) cured at ambient temperature were synthesized by semicontinuous-seeded emulsion polymerization with diacetone acrylamide (DAAM) and adipic dihydrazide (ADH) as crosslinkable monomers. The influences of DAAM monomer mass content, neutralizer, and curing temperature on the properties of self crosslinkable coreshell latices and the keto-hydrazide crosslinking were discussed. The spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), atomic force microscopy (AFM), transmission electron microscopy (TEM), and contact angle instruments were used to determine the structure and properties of PAs. The water evaporating rate during the film-forming process of self crosslinkable core-shell latices was also investigated. FTIR analyses demonstrate that the keto-hydrazide crosslinking reaction does not occur in the latex environment but occurs at ambient temperature with the evaporation of water during the film-forming process. The results of DSC show that the core-shell crosslinkable PAs have two glass transition temperatures (T g ), and T g s of crosslinked film are higher than that of non crosslinked fim. Moreover, the keto-hydrazide reaction is found to be acid catalyzed and favored by the loss of water and the simultaneous decrease in pH arising from the evaporation of ammonia or amines during filmforming process. Hence, in the volatile ammonia or amines neutralized latices, the latex pH value adjusted to 7-8, which not only ensure the crosslinkable latex with good storage stability but also obtain a coating film with excellent performances by introducing the keto-hydrazine crosslinking reaction.

Fluorine containing self‐crosslinking acrylic latexes with reduced flammability and their application as polymer binders for heterogeneous cation‐exchange membranes

“…It can be seen in both spectra as well that the PN cycle vibration was located at 1168 cm −1 and the stretching vibration and wagging vibrations of the CF bonds were detected at 1280 and 652 cm −1 , respectively, which reveals clearly that HACTP and TFEMA took part in the polymerization. When comparing the spectra of the copolymer without and after ADH crosslinking, the absorption peak at 1652 cm −1 corresponding to NC bonds can be observed in the case of ADH‐crosslinked copolymer (curve b), which confirms that the keto‐hydrazide crosslinking reaction has proceeded …”

“…These latexes can get cured rapidly at ambient temperature and do not need any additional crosslinker to be added before use. The reaction between the carbonyl functionalities of DAAM and hydrazide groups of ADH is favored by the loss of water and the simultaneous decrease in pH arising from the evaporation of ammonia or amines during the film forming process . The network formation mechanism based on the keto‐hydrazide crosslinking reaction is depicted schematically in Figure .…”

Studies on the ambient temperature crosslinking of latex films based on natural rubber grafted with poly(diacetone acrylamide) using DMTA

“…The crosslinking reaction in this system occurs preferentially after the loss of water during drying [7][8][9]. Diacetone acrylamide (DAAM) has generally been the monomer of choice for providing ketone pendant groups in acrylic latexes, since the ketone carbonyl of DAAM reacts rapidly with hydrazide at ambient temperatures [10,11].…”

Characterization of Molecular Structure of Emulsion Acrylic Microgels: Exploring the Impact of Molar Mass on Coating Properties of Self-Cross-Linkable Latexes

“…The reaction between the carbonyl functionalities of DAAM and hydrazine groups of ADH proceeds rapidly at ambient temperature and is favored by the loss of water and the simultaneous decrease in pH arising from the evaporation of ammonia or amines during the film forming process [21]. The network formation mechanism based on the keto-hydrazide crosslinking reaction is depicted schematically in Fig.…”