Search Results (20)

Room-temperature self-healing polyurethanes (PUs) generally show limited mechanical properties. In order to improve the mechanical properties of PUs without sacrificing their self-healing ability, in this study, different amounts of halloysite clay filler were added. Thus, intrinsically self-healing PUs were synthesized using polycarbonate diol polyol, aliphatic diisocyanate, 1,4-butanediol, and different amounts (0.5–10 wt.%) of thermally treated halloysite. During synthesis, the halloysite clay was added to the polyol. The structural, thermal, viscoelastic, and mechanical properties of the resulting halloysite-filled PUs were evaluated. All halloysite-filled PUs retained their room-temperature self-healing capability while exhibiting improved mechanical strength. The PU with 0.5 wt.% halloysite (E0.5) showed the most balanced performance, with well-dispersed halloysite nanotubes intercalated within the soft segments, enhancing chain mobility and soft segment ordering. Higher halloysite loadings (1–3 wt.%) led to increased mechanical properties but also some round clay particle agglomeration and surface migration, leading to limited halloysite–polyurethane interactions. The addition of more than 3 wt.% halloysite did not result in further improvements in mechanical properties. The findings of this study provide new insight into the filler–polymer interaction mechanism and establish a foundation for the design of multifunctional PUs with both autonomous self-repair and enhanced mechanical performance. Full article

A series of PPCDL-PEG₁₀₀₀-TPU were prepared by melting method using CO₂ based biodegradable polycarbonate diol (PPCDL) and polyethylene glycol (PEG1000) as soft segments, and hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) as hard segments. Their structure and properties were characterized to show that the products have nanoscale microphase separation, excellent wear-resistance and high resilience. PPCDL-PEG₁₀₀₀-TPUs have high tensile strength, high elongation at break, controllable hardness and excellent wear resistance when the content of hard segment is about 20%. Compared to PPCDL-TPU with only PPCDL as soft segment, the mechanical properties of TPU increase rather than decrease after the addition of PEG due to the crystallization behavior of PEG units in block copolymers. When the ratios of n_PPCDL:n_PEG are 10:1 and 4:1, the tensile strength of PPCDL-PEG₁₀₀₀-TPU reaches 27.5 MPa and 16.5 MPa (an increase of nearly 200% and 20% than PPCDL-TPU). The elongation at break reaches 1995% and 2485% (an increase of nearly 40% and 75% than PPCDL-TPU). Hardness of the prepared PPCDL-PEG₁₀₀₀-TPUs’ Shore A can be controlled in range of 70~85 by regulating the addition of PEG and their glass transition temperature (Tg) decreases with the increase of the amount of PEG incorporated. All PPCDL-PEG₁₀₀₀-TPUs exhibit good wear resistance with the average Akron wear volume of 12 mm³ after 4000 cycles of experiments according to national standards. PPCDL-PEG₁₀₀₀-TPUs show a high resilience performance with a negligible change in the hysteresis loop area after six cycles of tensile stretching. Furthermore, all PPCDL-PEG₁₀₀₀-TPUs possess high thermal stability, strong hydrophobicity, and low water absorption. This material has excellent application prospects and competitiveness in footwear and shock-absorbing materials. Full article

This study investigates the impact of polycarbonate diol (PCDL)-modified toluene diisocyanate (TDI)-based polyester polyurethane polishing pads on the chemical mechanical polishing of 4H silicon carbide (4H-SiC) substrates. Employing a unique metho, PCDL alters the ratio of polyurethane soft and hard segments, facilitating the one-step synthesis of a polishing pad via chemical foaming. The extent of the reaction of isocyanate groups was characterized by Fourier transform infrared spectroscopy, while the changes in the glass transition temperature of the material before and after modification were evaluated using differential scanning calorimetry. The mechanical properties and surface morphology of the modified pad have been systematically characterized. The results showed that compared with the polyurethane polishing pad without PCDL, tensile strength was augmented by a factor of 2.1, the elastic modulus surged by a factor of 4.2, the elongation at break improved by a factor 1.6, and the wear index decreased by a factor of 0.5 by 40 wt.% PCDL loading. Furthermore, the modified pad demonstrated a 14.5% increase in material removal rate and a reduction in surface roughness of 4H-SiC from 0.124 nm to 0.067 nm. Additionally, the compact surface pore structure and enhanced chemical stability in the strong oxidizing slurry of the modified pad enabled superior polishing performance, achieving an ultrasmooth 4H-SiC surface. The study highlights the potential of tailored polyurethane formulations in enhancing polishing efficiency and surface finish in semiconductor manufacturing processes. Full article

Polyurea (PUR) has been widely used as a protective coating in recent years. In order to complete the understanding of the relationship between PUR microstructure and its energy absorption capabilities, the mechanical and dynamic performance of PURs containing various macrodiol structural units were compared using material characterization techniques and molecular dynamic simulation. The results showed that the PUR polycarbonate diols formed as energy absorbing materials showed high tensile strength, high toughness, and excellent loss factor distribution based on the comparison of stress–strain tensile curves, glass transition temperatures, phase images, and dynamic storage loss modulus. External energy from simple shear deformation was absorbed to convert non-bond energy, in particular, based on fractional free volume, interaction energy, and total energy and hydrogen bond number change from the molecular dynamic simulation. Hydrogen bonds formed between soft segments and hard segments in the PURs have been proven to play a significant role in determining their mechanical and dynamic performance. The mechanical and dynamic properties of PURs characterized and tested using experimental techniques were quantified effectively using molecular dynamic simulation. This is believed to be an innovative theoretical guidance for the structural design of PURs at the molecular level for the optimization of energy absorption capabilities. Full article

The polycondensation of carbon dioxide and diols under atmospheric pressure has significant appeal, thus making the study of catalysts in this process very important. Here, a series of CeO₂-X catalysts (X = 9/11/13) with surface modification by basic sites was synthesized via simple impregnation in KOH solution. The structure and morphology of the CeO₂-X catalysts remained unchanged after KOH treatment. However, the specific surface area of modified catalysts showed a slight decrease compared with the unmodified samples due to the notable enhancement of basic sites on the surface, resulting in improvement of CO₂ adsorption capacity. Furthermore, the catalytic performance of the resultant CeO₂-X catalysts was evaluated by solvent-free polymerization of 1,6-hexanediol (HDO) and CO₂ at atmospheric pressure (0.1 MPa) using a well-designed reaction apparatus. As a result, the modified catalysts exhibited better performance for CO₂ activation due to the existence of abundant basic sites on the surfaces, while CeO₂-11 possessed the most favorable catalytic activity and displayed an enhancement of approximately 50% in production compared with that of unmodified CeO₂. Full article

A series of CO₂-based thermoplastic polyurethanes (TPUs) were prepared using CO₂-based poly(polycarbonate) diol (PPCDL), 4,4′-methylenebis (cyclohexyl isocyanate) (HMDI), and polypropylene glycol (PPG and 1,4-butanediol (BDO) as the raw materials. The mechanical, thermal, optical, and barrier properties shape memory behaviors, while biocompatibility and degradation behaviors of the CO₂-based TPUs are also systematically investigated. All the synthesized TPUs are highly transparent amorphous polymers, with one glass transition temperature at ~15–45 °C varying with hard segment content and soft segment composition. When PPG is incorporated into the soft segments, the resultant TPUs exhibit excellent self-healing and shape memory performances with the average shape fixity ratio and shape recovery ratio as high as 98.9% and 88.3%, respectively. Furthermore, the CO₂-based TPUs also show superior water vapor permeability resistance, good biocompatibility, and good biodegradation properties, demonstrating their pretty competitive potential in the polyurethane industry applications. Full article

Two polyurethanes (PUs) were similarly synthesized by reacting a cycloaliphatic isocyanate with 1,4-butanediol and two polyols of different nature (polyester, polycarbonate diol) with molecular weights of 1000 Da. Only the PU synthesized with polycarbonate diol polyol (YCD) showed intrinsic self-healing at 20 °C. For assessing the mechanism of intrinsic self-healing of YCD, a structural characterization by molecular weights determination, infrared and X-ray photoelectronic spectroscopies, differential scanning calorimetry, X-ray diffraction, thermal gravimetric analysis, and dynamic mechanical thermal analysis was carried out. The experimental evidence concluded that the self-healing at 20 °C of YCD was due to dynamic non-covalent exchange interactions among the polycarbonate soft segments. Therefore, the chemical nature of the polyol played a key role in developing PUs with intrinsic self-healing at 20 °C. Full article

A polyurethane series (PHEI-PU) was prepared via a one-shot bulk polymerization method using hexamethylene diisocyanate (HDI), polycarbonate diol (PCD), and isosorbide derivatives (ISBD) as chain extenders. The mechanical properties were evaluated using a universal testing machine (UTM), and the thermal properties were evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The PHEI-PU series exhibited excellent mechanical properties with an average tensile strength of 44.71 MPa and an elongation at break of 190%. To verify the applicability of different proportions of PU as an electrode binder, PU and Ag flakes were mixed (30/70 wt%) and coated on PCT substrates, the electrodes were evaluated by four-point probe before and after 50% elongation, and the dispersion was evaluated by scanning electron microscopy (SEM). The electrical resistance change rate of PHEI-PU series was less than 20%, and a coating layer with well-dispersed silver flakes was confirmed even after stretching. Therefore, it exhibited excellent physical properties, heat resistance, and electrical resistance change rate, confirming its applicability as an electrode binder for in-mold coating. Full article

Vinyl-capped cationic waterborne polyurethane (CWPU) was prepared using isophorone diisocyanate (IPDI), polycarbonate diol (PCDL), N-methyldiethanolamine (MDEA), and trimethylolpropane (TMP) as raw materials and hydroxyethyl methacrylate (HEMA) as a capping agent. Then, a crosslinked FPUA composite emulsion with polyurethane (PU) as the shell and fluorinated acrylate (PA) as the core was prepared by core-shell emulsion polymerization with CWPU as the seed emulsion, together with dodecafluoroheptyl methacrylate (DFMA), diacetone acrylamide (DAAM), and methyl methacrylate (MMA). The effects of the core-shell ratio of PA/PU on the surface properties, mechanical properties, and heat resistance of FPUA emulsions and films were investigated. The results showed that when w(PA) = 30~50%, the stability of FPUA emulsion was the highest, and the particles showed a core-shell structure with bright and dark intersections under TEM. When w(PA) = 30%, the tensile strength reached 23.35 ± 0.08 MPa. When w(PA) = 50%, the fluorine content on the surface of the coating film was 14.75% and the contact angle was as high as 98.5°, which showed good hydrophobicity; the surface flatness of the film was observed under AFM. It is found that the tensile strength of the film increases and then decreases with the increase in the core-shell ratio and the heat resistance of the FPUA film is gradually increased. The FPUA film has excellent properties such as good impact resistance, high flexibility, high adhesion, and corrosion resistance. Full article

There are no previous studies on the interactions between polyols of different nature as a model for understanding the interactions between soft segments in PUs. In this study, different blends of two polyols of different natures (polyester—PE, and polycarbonate diol—CD) and similar molecular weights were prepared and their structural, thermal, surface, viscoelastic, and self-adhesion properties were assessed. Different experimental techniques were used: infrared spectroscopy (ATR-IR), differential scanning calorimetry (DSC), X-ray diffraction, thermal gravimetric analysis (TGA), and plate–plate rheology. PE showed a larger number of structural repeating units and a higher number of polar groups than CD, but the carbonate–carbonate interactions in CD were stronger than the ester–ester interactions in PE. The blending of CD and PE imparted synergic structural properties, particularly in the blends containing less than 50 wt.% PE, they were associated with the disrupt of the carbonate–carbonate interactions in CD and the formation of new ester–carbonate and hydroxyl–carbonate interactions. CD + PE blends with less than 50 wt.% PE exhibited higher glass transition temperatures, a new diffraction peak at 2θ = 24°, one additional thermal degradation at 426–436 °C, and a less-steep decline of the storage moduli. Furthermore, the different interactions between the polyol chains in the blends were also evidenced on their surface properties, and all CD + PE blends showed self-adhesion properties which seemed related to the existence of ester–carbonate and carbonate–carbonate interactions. Full article

Waterborne polyurethane (WPU) is a waterborne coating with excellent physicochemical properties. Its deficiencies of water resistance, chemical resistance, staining, and hardness have limited the wide application of polyurethane in the wood lacquer market. In this study, polycarbonate diols (PCDL) were used as soft segments and WPCU was modified by cross-linking using Trimethylolpropane (TMP) to prepare polycarbonate type WPU (WPCU) with cross-linked network structure. The new wood lacquer was prepared by adding various additives and tested by applying it on wood board. The successful synthesis of WPCU was determined by FTIR testing, and the cross-linking degree of WPCU was probed by low-field NMR. The viscosity of the cross-linked WPCU emulsion showed a decreasing trend compared to the uncross-linked WPCU emulsion, and WPCU-2 had the smallest particle size. Compared with the uncrosslinked WPCU film, the crosslinked WPCU film had lower water absorption (2.2%), higher water contact angle (72.7°), excellent tensile strength (44.02 MPa), higher thermomechanical, and better water and alcohol resistance. The effect of crosslinker content on the microphase separation of WPCU chain segments on the surface roughness of the film was investigated by SEM. The wood paint prepared by WPCU emulsion has good dry heat resistance, chemical resistance, and adhesion, and the hardness of the wood paint when the TMP content is 3% reaches H. It also has good resistance to sticky stains, which can be used to develop new wood lacquer. Full article

Isosorbide is a bio-based renewable resource that has been utilized as a stiffness component in the synthesis of novel polymers. Modified isosorbide-based bis(2-hydroxyethyl)isosorbide (BHIS) has favorable structural features, such as fused bicyclic rings and a primary hydroxyl function with improved reactivity to polymerization when compared to isosorbide itself. Polyurethane series (PBH PU series) using polycarbonate diol (PCD) and bis(2-hydroxyethyl)isosorbide (BHIS) were polymerized through a simple, one-shot polymerization without a catalyst using various ratios of BHIS, PCD, and hexamethylene diisocyanate (HDI). The synthesized BHIS and PUs were characterized using proton nuclear magnetic resonance (¹H-NMR), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), and mechanical testing. To determine the feasibility of using these PUs as biomedical materials, we investigated the effects of their BHIS content on PBH PU series physical and mechanical properties. The PBH PU series has excellent elasticity, with a breaking strain ranging from 686.55 to 984.69% at a 33.26 to 63.87 MPa tensile stress. The material showed superb biocompatibility with its high adhesion and proliferation in the bone marrow cells. Given their outstanding mechanical properties and biocompatibility, the polymerized bio-based PUs can contribute toward various applications in the medical field. Full article

APCs (aliphatic polycarbonates) are one of the most important types of biodegradable polymers and widely used in the fields of solid electrolyte, biological medicine and biodegradable plastics. Zinc-based catalysts have the advantages of being low cost, being non-toxic, having high activity, and having excellent environmental and biological compatibility. Zinc (II) acetylacetonate (Zn(Acac)₂) was first reported as a highly effective catalyst for the melt transesterification of biphenyl carbonate with 1,4-butanediol to synthesize poly(1,4-butylene carbonate)(PBC). It was found that the weight-average molecular weight of PBC derived from Zn(Acac)₂ could achieve 143,500 g/mol with a yield of 85.6% under suitable reaction conditions. The Lewis acidity and steric hindrance of Zn²⁺ could obviously affect the catalytic performance of Zn-based catalysts for this reaction. The main reasons for the Zn(Acac)₂ catalyst displaying a higher yield and M_w than other zinc-based catalysts should be ascribed to the presence of the interaction between acetylacetone ligand and Zn²⁺, which can provide this melt transesterification reaction with the appropriate Lewis acidity as well as the steric hindrance. Full article

A series of novel modified waterborne polyurethane acrylate (WPU-EA) emulsions were prepared with isophorone diisocyanate (IPDI), polycarbonate diol, 2,2-bis-hydroxymethyl-propionic acid (DMPA), 1,4-butanediol (BDO), epoxy acrylate (EA), and pentaerythritol triacrylate (PETA). The structure of WPU-EA was confirmed by FTIR and ¹H NMR spectroscopy. The effects of different dosages of epoxy acrylate on the cured film were investigated by tensile properties, dynamic mechanical analysis and thermogravimetric analysis. The results indicate that with increasing content of epoxy acrylate, the average particle size of the emulsion gradually increases. With the rise in epoxy acrylate concentration from 0%, 3.0%, 6.0% to 9.0%, the gel fraction of the cured film increases from 83.7%, 92.5%, 93.0% to 93.6%, respectively, and the glass transition temperature rises from 90.3 °C, 107.5 °C, 141.9 °C to 146.6 °C. The tensile strength and the thermal stability of the cured film increases, and the elongation at break decreases. Moreover, the WPU-EA emulsions were sprayed on polycarbonate sheets and exhibited the advantages of high hardness, better gloss and good adhesion, which is promising for the application of plastic coatings. Full article

The new segmented poly(thiourethane-urethane)s (PTURs) based on 1,1′-methanediylbis(4-isocyanatocyclohexane) (HMDI, Desmodur W^®), polycarbonate diol (PCD, Desmophen C2200) and (methanediyldibenzene-4,1-diyl)dimethanethiol were synthesized by one-step melt polyaddition method. The obtained PTURs, with a content of 30–60 wt% of the hard segments (HS), were tested in which the influence of changes in the HS content on their properties was determined. The polymers were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), thermal analysis (DSC, TGA) and thermomechanical analysis (DMTA). Additionally, tensile strength, optical (refractive index, UV-VIS and color) and surface properties of the obtained polymers (contact angle and surface free energy) and adhesion to copper were examined. FTIR analysis verified the supposed structure of the polymers obtained and showed a complete conversion of the isocyanate groups. TGA analysis confirmed the relatively good thermal stability of the polymers. On the other hand, after performing the DSC analysis, it was possible to state that the obtained materials were partially or completely amorphous, and the microphase separation decreased with increasing HS content in the polymer. Similar observations were made from the DMTA data. In addition, the hardness, tensile strength, modulus of elasticity, storage modulus, adhesion to copper, refractive index and total free surface energy increased with increasing HS content in the polymer. Full article