Dimethylol Propionic Acid Content Research Articles

Surface characteristics of UV-irradiated chitin-based shape memory polyurethanes

Shape memory polyurethanes (SMPUs) were prepared from polycaprolactone diol 4000 (PCL 4000), 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (BDO), chitin, dimethylol propionic acid (DMPA), and triethylamine (TEA). The synthesized samples were irradiated for 50, 100, and 200 h in an UV exposure unit. The effects of chitin and DMPA contents in the polyurethane (PU) formulation on surface properties of the UV-irradiated PU samples were investigated by contact angle measurements, surface free energy and water absorption (%), total work of water adhesion to polymer and equilibrium degree of swelling. Results of the aforementioned surface techniques revealed that the UV-irradiated PU samples were affected by varying the UV exposure period. The interactions of the PU films with solvents on the surface were clearly related to the contents of DMPA and chitin in the final polyurethane formulation and UV-irradiation time.

Surface characteristics of chitin-based shape memory polyurethane elastomers

Shape memory polyurethanes (SMPUs) were prepared from polycaprolactone diol 4000 (PCL 4000), 1,4-butanediol (BDO), chitin, dimethylol propionic acid (DMPA), triethylamine (TEA) and 4,4′-diphenylmethane diisocyanate (MDI), and the structures of the synthesized materials were verified by infrared spectroscopy. The effects of chitin and DMPA contents in the polyurethane formulation on surface properties were investigated. DMPA provides function of making hydrophilic polyurethanes. The crystalline structure of chitin enhanced the hydrophobicity of the synthesized materials. Contact angle, water absorption, surface free energy, work of water adhesion and swelling behavior of the synthesized polyurethanes were affected by varying the DMPA and chitin contents. The interactions of the PU films with solvents on the surface were clearly related to the contents of DMPA and chitin in the final polyurethane formulation.

Synthesis and characterization of novel biodegradable and biocompatible poly(ester-urethane) thin films prepared by homogeneous solution polymerization

Novel biodegradable and biocompatible poly(ester-urethane)s were synthesized by in situ homogeneous solution polymerization of poly(ɛ-caprolactone) diol, dimethylolpropionic acid (DMPA), and methylene diphenyl diisocyanate in acetone followed by solvent exchange with water. The effects of the DMPA content and hard segment content on the properties of the polyurethanes were measured by DSC, TGA, and hydrolytic degradation measurements. The results showed that DMPA had a dramatic effect on the particle size; the particle size decreased rapidly with increasing DMPA content. The hydrolytic degradation test showed that the degradation rate was little affected by the DMPA content in the range investigated, but was observed to be influenced by the hard segment content. Cell toxicity analysis showed that the biodegradable poly(ester-urethane)s synthesized in this study did not exhibit any detectable toxicity to human umbilical vein endothelial cells and mouse embryonic stem cells. Both types of cells can effectively adhere to and spread on the surface of pure poly(ɛ-caprolactone) or poly(ester-urethane)s. The present study demonstrates the feasibility of a facile synthesis of biodegradable polyurethanes and of their aqueous dispersions with prescribed properties for biomedical applications.

Preparation and characterization of aqueous polyurethane dispersions containing ionic centers

AbstractAqueous polyurethane dispersions were prepared from toluene di‐isocyanate, polytetramethylene glycol, and 1,4‐butanediol, with different weight percent of dimethylol propionic acid (DMPA) as anionic center. IR Spectroscopy was used to follow the polymerization reaction as well as the polymer characterization. The effect of DMPA content on the state of dispersion, particle size distribution, mechanical, and thermal properties of the emulsion‐cast films were studied. Average particle size of the prepared emulsion polyurethanes decreased with increasing DMPA content. Tensile strength and hardness increase and elongation at break and contact angle decrease by increasing the ionic content. Glass transition temperature (Tg) shifted toward higher temperature and thermal stability decreased by increasing the DMPA content. The increased Tg and tensile properties are interpreted in terms of the increased hard segments and coulombic forces between ionic centers. The decreased contact angle is ascribed to the increase in the hydrophilicity of the polyurethanes because of the incorporation of more hydrophilic moiety in polymer backbone. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3931–3937, 2007

Effect of polyisocyanate hardener on waterborne polyurethane adhesive containing different amounts of ionic groups

Waterborne polyurethane (WBPU) adhesive with varying amounts of dimethylol propionic acid (DMPA) was synthesized by prepolymer process and blended with polyisocyanate hardener. The mean particle size of the WBPU dispersion decreased with increasing DMPA content.1H NMR spectroscopy confirmed the formation of allophanate bonds and biuret bonds due to the reaction of hardener NCO with urethane/urea groups. The optimum NCO content with the greatest adhesive strength was dependent on the total content of urethane/urea groups in the WBPU molecules. The optimum NCO content increased with increasing number of urethane groups (DMPA content). The adhesion strength of WBPU adhesives was maximized at a molar ratio of hardener NCO to urethane/urea of about 0.28.

Structural characterization and mass transfer properties of nonporous segmented polyurethane membrane: Influence of hydrophilic and carboxylic group

An attempt has been made to investigate the influence of hydrophilic and carboxylic groups on structure and mass transfer properties of polypropylene glycol (number average molecular weight of 1000 g mol −1, PPG 1000) based segmented polyurethane (SPU). Polyethylene glycol (number average molecular weight of 3400 g mol −1, PEG 3400) (hydrophilic segment) or dimethylol propionic acid (DMPA) (carboxylic group) or combination of PEG 3400 and DMPA were used to modify the SPU. For comparison, SPU without hydrophilic/carboxylic group was also synthesized. Structures were investigated by Fourier-transform infrared (FT-IR), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and tensile tester. Mass transfer properties were investigated by equilibrium sorption and water vapor permeability measurements. FT-IR spectra of C O stretching was indicated that with the introduction of hydrophilic or acid groups in the polymer backbone, the hydrogen bonding of urethane groups were became weaker or stronger respectively. Nearly amorphous structures of all SPU samples were evidenced by WAXD and DSC results. The presence of DMPA increases the interaction between the polymer chains, which increases the glass transition temperature ( T g) and make the polymer tough. In contrast flexible PEG 3400 segment decreases the T g and increases the percent strain at maximum load. Experimental results revealed that the mass transfer properties not only influenced by amorphous region but also on the interaction between the polymer chains. Presence of hydrophilic group enhances the sorption as well as water vapor permeability (WVP). Abrupt changes of mass transfer properties were observed for SPU with PEG 3400 due the presence of more polar group and longer flexible chains of PEG 3400 which will originates holes in the polymer membranes. The membrane with DMPA content, lowest permeabilities was characterized by a higher degree of physical cross-linking imposed by carboxylic functionality.

Characterization of waterborne polyurethane adhesives containing different amounts of ionic groups

Waterborne polyurethane adhesives are an interesting alternative to the current solvent-based polyurethane adhesives used in footwear industry. In this study, different aqueous polyurethane dispersions were prepared by using the prepolymer mixing process. The ionic groups content in the polyurethane ionomer structure was varied by changing the amount (5 and 8 wt% (with respect to the prepolymer weight) of the internal emulsifier—dimethylolpropionic acid (DMPA). The decrease in the DMPA content slightly increased the particle size in number due to the decrease in both the hydrophilicity of the polyurethane ionomer, and the electrolytic stability of the aqueous polyurethane dispersion. Furthermore, the lower the DMPA amount, the lower the hard segment content in the ionomer and the higher the crystallinity of the polyurethane; however, the resistance to flow under temperature (i.e. thermoplasticity) was reduced. The resistance to thermal degradation of the polyurethane ionomer increased by decreasing the DMPA content due to the lower hard segment content. Finally, high initial adhesive strength was obtained and the adhesion to PVC increased as the DMPA content in the polyurethane ionomer decreased.

Seeded emulsion polymerization of methyl methacrylate using aqueous polyurethane dispersion: effect of hard segment on grafting efficiency

Seeded emulsion polymerization of methyl methacrylate (MMA) using aqueous polyurethane dispersion as seed particle was undertaken to investigate the effect of hard segment on the grafting efficiency. The hard segment consists of isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA), where the portion of hard segment varied from 19.6 to 35.4%. The effects of IPDI and DMPA contents on the grafting efficiency were confirmed by both FT-IR and thin layer chromatograph equipped with flame ionization detector (TLC/FID). The grafting efficiency increased with increasing hard segment content, i.e. IPDI and DMPA. From the quantitative results of FT-IR spectra and TLC/FID analysis, it was found that the relative area of NH peak (1550 cm −1 ) varied significantly against the contents of IPDI. These results suggested that NH bonds in the hard segment play an effective role of grafting reaction with MMA.

Effect of process variables on molecular weight and mechanical properties of water-based polyurethane dispersion

Water-based polyurethane dispersions (PUD) were prepared by polyaddition reaction using poly (hexamethylene adipate) glycol (polyol 66), isophorone diisocyanate (IPDI), dimethylol propionic acid (DMPA), and 1,6-hexane diamine (HDA) as chain extender. Various formulations were designed to investigate the effects of process variables such as molar ratio of NCO to OH (NCO/OH), DMPA content, and neutralization degree on molecular weight and mechanical properties. Universal testing machine (UTM) was used for the mechanical properties of emulsion cast film of the PUD. The molecular weights were measured by gel permeation chromatography (GPC). Evolution of the weight average molecular weight ( M ̄ w ) and mechanical properties were significantly affected by the neutralization degree during the chain extension. It was found that the M ̄ w increased when the NCO/OH molar ratio increased, subsequently mechanical properties such as tensile strength and 100% modulus improved dramatically. However, the elongation decreased as the NCO/OH increased.

The effect of DMPA units on ionic conductivity of PEG–DMPA–IPDI waterborne polyurethane as single-ion electrolytes

The waterborne polyurethane (WPU) dispersions synthesized from poly(ethylene glycol) (PEG), dimethylol propionic acid (DMPA), and isophorone diisocyanate (IPDI) with various DMPA contents were prepared from our modified acetone process. Differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FT-i.r.), and wide-angle X-ray diffraction spectroscopy (WAXD) were utilized to characterize WPU films for the behavior of their crystallinity and H-bonding. Alternating current (AC) impedance experiments were performed to determine the ionic conductivities of WPU films and their corresponding gel electrolytes. One of the investigated WPU gel electrolytes exhibits an ionic conductivity as high as ∼10 −5 S/cm at room temperature.

Preparation and Properties of Water-borne Polyurethanes

Department of Polymer Science and Engineering, Pusan National University, Pusan 609-735, Korea(Received 22 July 1996; accepted 6 August 1996)Abstract: Following a prepolymer mixing process, polyurethane (PU) aniono-mer dispersions were prepared from polyethylene adipate glycol (PEA), iso-phorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI) and dimethylolpropionic acid (DMPA) as a potential ionic centre. E†ects of prepolymer molec-ular weight, PEA molecular weight, hard segment content, DMPA content,degree of neutralization and mixed diisocyanates have been studied in terms ofparticle size and viscosity of emulsion, and surface, mechanical and dynamicmechanical properties of the emulsion-cast Ðlms. Particle size decreased andemulsion viscosity increased with increase in prepolymer molecular weight andPEA molecular weight, DMPA content, the degree of neutralization and IPDIcontent in mixed isocyanate systems. The decrease in particle size was due toincreased chain Nexibility and/or hydrophilicity of the PU. The mechanical anddynamic mechanical properties of the PU ionomer dispersions were interpretedin terms of soft segmentEhard segment phase separations, hard segment content,chain Nexibility and coulombic forces.Key words: polyurethanes, anionomer dispersions, structureEproperty corre-lation, mechanical properties, dynamic mechanical properties.

Structure-property relationships of polyurethane anionomer acrylates

Abstract Polyurethane (PU) ionomer acrylates and non-ionomer acrylates were synthesized from poly(propylene glycol) (PPG), isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), 2-hydroxyethylacrylate (HEA), and N-vinylpyrrolidone (NVP), tripropyleneglycol triacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), and were characterized in terms of water swell, mechanical, and dynamic mechanical properties in response to their structure. At fixed DMPA content (PPG/DMPA 8/2), neutralization caused an inward migration of soft segment glass transition (Tgs) and hard segment glass transition (Tgh) in PU acrylate without diluent. However, with increasing DMPA (ionized) content, Tgh increased keeping Tgs constant, together with an increase in equilibrium swell, tensile modulus, tensile strength, and the rubbery plateau modulus. At a fixed diluent level (20%), tensile strength and Tgh increased in the order of no diluent

Aqueous Dispersion of Polyurethane Anionomer from Aliphatic Diisocyanates and Poly(Hexamethylene Carbonate) Diol

Abstract Water dispersible polyurethanes (PUs) were prepared from poly(hexamethylene carbonate) (PHC) diol, isophorone diisocyanates (IPDI), hexamethylene diisocyanate (HDI), and dimethylolpropionic acid (DMPA) as latent anionic sites. After neutralization of the carboxyl group from the DMPA unit with triethylamine (TEA), the PU anionomers were dispersed by adding water, following by crosslinking using triethylenetetramine (TETA). The particle size of the dispersion decreased with the content of DMPA and increased with HDI in the HDI-IPDI system, and it exhibited a minimum when the number-average molecular weight (M n) of the prepolymer was 3000 and 4500, respectively. PUs with a higher content of hard segments from DMPA or TETA, or with a higher content of IPDI rather than HDI, had higher tensile moduli and storage moduli at room temperature. Ultimate tensile properties increased with an increase of the prepolymer molecular weight and the DMPA and HDI content.

Polyurethane Anionomer Dispersion from Ether-Type Polyols and Isophorone Diisocyanate

Abstract Polyurethane (PU) anionomer dispersions were formulated from polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), dimethylol propionic acid (DMPA), and isophorone diisocyanate following a prepolymer mixing process. Effect of ionic content, mixing ratio of polyols (PPG/PTMG), and polyol molecular weight on the emulsion characteristics and the dynamic mechanical and tensile properties of the emulsion-cast films were studied. Particle size decreased with increasing DMPA, PPG content, and the molecular weight of PTMG. The glass transition temperature of the soft segment was almost independent of the DMPA content and the molecular weight of PTMG, but increased with PPG content in the mixed polyol system, due probably to the increased phase mixing between soft and hard segments.