t‐Butyl‐Oxycarbonylated Diamines as Building Blocks for Isocyanate‐Free Polyurethane/Urea Dispersions and Coatings

Abstract

t-Butyl-oxycarbonylated diamines ("di-Boc-carbamates") are investigated as dicarbamate monomers for diamine/dicarbamate polymerizations. Polyureas (PUs) and polyurethanes (PURs) with high molecular weights are prepared from stoichiometric polymerizations of diamines or diols with N-N'-di-t-butyl-oxycarbonyl isophorone diamine (DiBoc-IPDC) using KOt-Bu as a catalyst, while gelation is observed when an excess of DiBoc-IPDC is used with respect to the diamines or diols. Stable dispersions are obtained from PUs and PURs with 3,3'-diamino-N-methyldipropylamine (DMDPA) as internal dispersing agent. The corresponding PU-based coatings exhibit superior mechanical properties and solvent resistances compared to the polyurethane urea coatings synthesized from diols, DiBoc-IPDC, and DMDPA.

Water-based non-isocyanate polyurethane-ureas (NIPUUs)

“…In 2018, Ma et al published a series of studies exploring nonisocyanate strategies for the production of waterborne polyurea dispersions for coatings. 60,61 Their approach consisted in utilizing a transurethanization-like process in bulk under vacuum. To do so, they copolymerized a bis-alkylcarbamate monomer with two diamines, one of them playing the role of internal dispersing agent (IDA) to form a pre-polymer, that was further dissolved in methanol.…”

“…The authors demonstrated that during the preliminar transurethanization-based step, the nature of the alkyl-leaving group of the bis-carbamate as well as the process conditions (such as high vacuum) were of outmost importance to obtain polyureas of high molar masses. 60,61 The successful implementation of this process thus strongly depends on the ability of the transurethanization reaction to proceed without too many side-reactions. The nucleophilic attack of the diamine onto the bis-carbamate to yield the corresponding urea moiety is in competition with the Nalkylation reaction that can proceed through a decarboxylation mechanism -Scheme 9.…”

“…Ma et al demonstrated that the N-alkylation reaction could be mitigated by changing the alkyl moiety located on the biscarbamate compound. 60,61 Bulkier alkyl-groups reduced the rate of the decarboxylation process, thus favoring the polyurea formation. Indeed, the tert-butoxyl moiety was more selective towards urea formation than the ethyl groups, which itself was more selective than methyl groups.…”

Self‐assembled polyurea macromer nanodispersion and resulting hybrid polyurea‐acrylic emulsions and films

“…To facilitate hybridization, developing a dispersion of PU or PUr is a critical first step. The development of PUDs and PUr dispersions (PUrD) have gained interest due to the significantly lower volatile organic compound (VOC) content relative to their solvent borne equivalents. In both PUD and PUrD systems, an internal dispersing agent (IDA) is included to impart colloidal stability through neutralized carboxylic acid or cationic functionality.…”

Light‐Responsive Serinol‐Based Polyurethane Nanocarrier for Controlled Drug Release

“…The nanocarriers are advantageous for improving the solubility of hydrophobic drugs, releasing the payload in a controlled manner, and reducing toxic side effects . Polyurethanes (PUs) are an important family of biocompatible polymers and have been widely applied in biomedical areas, such as drug delivery, tissue engineering, and adhesives, due to their good physical and thermal properties, and good biocompatibility . Recently, PU nanoparticles with stimuli‐responsive properties, including pH, redox, and temperature sensitivity have been widely investigated as drug carriers.…”