A series of waterborne polyurethanes (WBPU) containing different amount of 2,2-bis(hydroxymethyl) propionic acid (DMPA) were synthesized using prepolymer mixing process. Relationships between the DMPA content and physical, mechanical, and thermal properties as well as adhesive behavior at different condition were investigated. Stable aqueous dispersions of WBPU were obtained when the DMPA content was more than 10 mol %. At higher DMPA content, the particle size of the WBPU dispersion was lower but the viscosity of the dispersion was higher. Water swelling and tensile strength of the films increased with increasing of DMPA content. The optimum adhesive strength of WBPU adhesives was found to be depended on the DMPA content, pressing temperature, and pressure on adhesion process. The adhesive strength of WBPU adhesives increased with increasing DMPA content. The optimum pressing temperature decreased with increasing DMPA content. The adhesive strength of WBPU adhesives increased with increasing pressure up to 15 kg f/cm 2 and then leveled off. The optimum pressing temperature of WBPU adhesives samples containing 24.02, 22.05, and 17.05 mol % DMPA was about 100, 120, and 1408C, respectively.

A series of waterborne polyurethane (WBPU)/multiwalled carbon nanotube (CNT) and WBPU/nitric acid treated multiwalled carbon nanotube (A‐CNT) composites were prepared by in situ polymerization in an aqueous medium. The optimum nitric acid treatment time was about 0.5 h. The effects of the CNT and A‐CNT contents on the dynamic mechanical thermal properties, mechanical properties, hardness, electrical conductivity, and antistatic properties of the two kinds of composites were compared. The tensile strength and modulus, the glass‐transition temperatures of the soft and hard segments (Tgs and Tgh, respectively), and ΔTg (Tgh − Tgs) of WBPU for both composites increased with increasing CNT and A‐CNT contents. However, these properties of the WBPU/A‐CNT composites were higher than those of the WBPU/CNT composites with the same CNT content. The electrical conductivities of the WBPU/CNT1.5 and WBPU/A‐CNT1.5 composites containing 1.5 wt % CNTs (8.0 × 10−4 and 1.1 × 10−3 S/cm) were nearly 8 and 9 orders of magnitude higher than that of WBPU (2.5 × 10−12 S/cm), respectively. The half‐life of the electrostatic charge (τ1/2) values of the WBPU/CNT0.1 and WBPU/A‐CNT0.1 composites containing 0.1 wt % CNTs were below 10 s, and the composites had good antistatic properties. From these results, A‐CNT was found to be a better reinforcer than CNT. These results suggest that WBPU/A‐CNT composites prepared by in situ polymerization have high potential as new materials for waterborne coatings with good physical, antistatic, and conductive properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3973–3985, 2005

Nitric acid treated multiwalled carbon nanotubes (A-CNTs) were dispersed in a waterborne polyurethane (WBPU) matrix to obtain WBPU/A-CNT nanocomposite films (99.99/0.01-98.5/1.5) with enhanced thermal, mechanical, and electrical properties. By X-ray photoelectron spectroscopy (XPS), the oxygen content of the carbon nanotube (CNT) surface was found to increase with increasing acid treatment time. With increasing acid treatment time, the contact angle of the CNT surface was significantly decreased from 15 to 0°. The mean particle sizes of the raw CNT and A-CNT aqueous solutions were 404.2 and 17.2 nm, respectively, indicating that the acid treatment led to a reduced agglomeration of CNTs. The electrical conductivity of raw CNT was 23 S/cm, and that of A-CNT significantly increased with increasing acid treatment time up to 30 min and then decreased a little. By dynamic mechanical thermal analysis, the storage modulus and loss tangent peak temperature (the glass-transition temperature) of the WBPU/A-CNT nanocomposites were found to increase with increasing A-CNT content. The initial tensile moduli and tensile strengths of the nanocomposite film with 1.5 wt % loading of A-CNT were enhanced by about 19 and 12%, respectively, compared to the corresponding values for the original WBPU film. The WBPU/A-CNT1.5 nanocomposite film containing 1.5 wt % of A-CNT exhibited a conductivity of 1.2 ϫ 10 Ϫ4 S/cm, which was nearly eight orders of magnitude higher that of the WBPU film (2.5 ϫ 10 Ϫ12 S/cm). The antistatic half-life ( 1/2 ) of the WBPU film was about 110 s, indicating that pure the WBPU film was a typical electrostatic material. However, those of the WBPU/A-CNT nanocomposites decreased exponentially with increasing A-CNT content. The WBPU/A-CNT1.5 sample, containing 1.5 wt % of A-CNT and with a 1/2 of 1 s, had good antistatic properties.

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To accomplish ideal wound healing dressing, a series of waterborne polyurethane (WBPU) hydrogels based on polyethylene glycol (PEG) were synthesized by polyaddition reaction in an emulsion system. The stable WBPU hydrogels which have remaining weight of above 85% were obtained. The effect of the soft segment (PEG) content on water absorbability of WBPU hydrogels was investigated. Water absorption % and equilibrium water content (%) of the WBPU hydrogel significantly increased in proportion to PEG content and the time of water-immersion. The maximum water absorption % and equilibrium water content (%) of WBPU hydrogels containing various PEG contents were in the range of 409-810% and 85-96%, respectively. The water vapor transmission rate of the WBPU hydrogels was found to be in the range of 1490-3118 g/m(2)/day. These results suggest that the WBPU hydrogels prepared in this study may have high potential as new wound dressing materials, which provide and maintain the adequate moist environment required to prevent scab formation and dehydration of the wound bed. By the wound healing evaluation using full-thickness rat model experiment, it was found that the wound covered with a typical WBPU hydrogel (HG-78 sample) was completely filled with new epithelium without any significant adverse reactions.