Aqueous-based Polyurethane Dispersions Research Articles

Polyurethane coating with thin polymer films produced by plasma polymerization of diglyme

Aqueous-based polyurethane dispersions have been widely utilized as lubricants in textile, shoes, automotive, biomaterial and many other industries because they are less aggressive to surrounding environment. In this work thin films with different thickness were deposited on biocompatible polyurethane by plasma polymerization process using diethylene glycol dimethyl ether (Diglyme) as monomer. Molecular structure of the films was analyzed by Fourier Transform Infrared spectroscopy. The spectra exhibited absorption bands of O-H (3500-3200cm-1), C-H (3000-2900cm-1), C=O (1730-1650cm-1), C-O and C-O-C bonds at 1200-1600cm-1. The samples wettability was evaluated by measurements of contact angle using different liquids such as water, glycerol, poly-ethane and CMC. The polyurethane surface showed hydrophilic behavior after diglyme plasma-deposition with contact angle dropping from 85° to 22°. Scanning Electron Microscopy revealed that diglyme films covered uniformly the polyurethane surfaces ensuring to it a biocompatible characteristic.

A new curing agent for self-curable system of aqueous-based PU dispersion

Anionic aqueous-based polyurethane (PU) dispersion consists of carboxyl group that served as an internal emulsifier stabilizing aqueous PU dispersion and also a reactive site toward curing agent. A model reaction of a mono-azetidine-containing compound and trimethylacetic acid (TMAA) demonstrated that an amino ester bond formation between azetidine and carboxylic acid. A di-azetidine containing compound (HDDA–AZT) was prepared and served as a curing agent, which was synthesized by a Michael addition reaction of azetidine (AZT) to hexanediol diacrylate (HDDA). Anionic aqueous PU dispersion was treated with HDDA–AZT as a latent curing agent and becoming a self-curable aqueous PU system. A cross-linked PU resin was obtained from this self-curing PU system on drying at ambient temperature. The performance properties of these self-cured PU resins proved that cross-linking behaviors with this new curing agent, HDDA–AZT.

Self-curable system of an aqueous-based polyurethane dispersion via a ring-opening reaction of azetidine end groups

An azetidine (AZT) containing compound, 3-azetidinyl propanol was synthesized from methyl acrylate with 3-amino-1-propanol in a four-step reaction. It was introduced into an isocyanate-terminated carboxylic acid containing polyurethane (PU) prepolymer as the end group. A single-component, AZT-terminated self-curable aqueous-based PU dispersion was obtained from the water dispersion process after it was neutralized with triethylamine. Its carboxylic groups served not only as the internal emulsifier stabilizing the aqueous PU dispersion but also as PU self-curing sites toward its AZT end groups via a ring-opening reaction. The curing reaction took place on drying and resulted in polymeric network structure formation among the polymers. The performance properties of this self-cured PU were evaluated in this study. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4383–4393, 2006

Dual-curing of anionic aqueous-based polyurethanes at ambient temperature

Polyurethane (PU) prepolymers are prepared by a polyaddition of isophorone diisocyanate, polypropylene glycol-1000, and 2,2-dimethylolpropanic acid. The anionic aqueous-based PU dispersions are derived from a water dispersion process of these NCO-terminated PU prepolymers together with a neutralization and a chain extension. They have both terminal amino and pendent carboxylic groups which are potentially reactive sites toward a di-functional epoxy and a tri- or di-aziridinyl compound of a dual-curing PU system, respectively. The stabilities of the resulting PU dispersions on zeta potential and particle size distributions are investigated. The improvements on mechanical, physical, and thermal properties of these dual-cured PU systems are also evaluated.