Polydimethylsiloxane, dihydroxy terminated: Modifier for High-Performance Polyurethanes

Polydimethylsiloxane, dihydroxy terminated is a silicon-basedorganic polymer that is nontoxic, optically clear, inert, and inflammablematerial. It is widely used in heat-resistant lubricants, fire retardants,medical devices, and cosmetics. Polydimethylsiloxane is hydrophobic,cytocompatible, and viscoelastic which can be used to prepare water-repellentcoatings in the textile industry. Effects of surface modification with Polydimethylsiloxane, dihydroxy terminated on the corrosion protection of polyurethane coating: This study investigates the improvement of corrosion resistance in polyurethane coatings through modification with hydroxy-terminated PDMS, highlighting its effectiveness in enhancing protective properties. Fabrication of silicone modified polyurethane matrix superhydrophobic coating with Polydimethylsiloxane, dihydroxy terminated modified SiO2 nanoparticles: The study explores the use of hydroxy-terminated PDMS in creating superhydrophobic surfaces for coatings, showing its utility in advanced material applications. High glass transition temperature shape‐memory materials: Hydroxyl‐terminated polydimethylsiloxane‐modified cyanate ester.

Hydroxyl-terminated polydimethylsiloxane on high-strength biocompatible polycarbonate urethane films

Polyurethanes always have a linear segmented copolymer structure generally composed of a relatively flexible component derived from macrodiols containing two or more hydroxyl groups called the soft segment, and a relatively hard and stiff component derived from a diisocyanate with two or more isocyanate groups and a chain extender, called the hard segment. Among the more recent and novel efforts, our group have incorporated a non-polar Polydimethylsiloxane, dihydroxy terminated macrodiol into the polyurethane backbone in order to further enhance the biostablity and physical performances of TPUs derived from PCDL macrodiols and H12MDI diisocyanate. To the best of the authors’ knowledge, Polydimethylsiloxane, dihydroxy terminated is a kind of the most extensively utilized polymeric raw material for the manufacture of biomedical devices with efficient biocompatibility, excellent hydrolytic and oxidative stability, low toxicity and high resistance to protein and platelet adhesion. Based on the above considerations, in the present study, a unique route was developed to obtain a novel type of polyurethane with relatively stable mechanical behavior and high biocompatibility. Thermal polycarbonate urethanes (TPUs) with small amounts of hydroxyl-terminated Polydimethylsiloxane, dihydroxy terminated were synthesized through a two-step solution polymerization strategy using PDMS–PCDL macrodiols as the soft segment and H12MDI and the chain extender BDO as the hard segment.[1]

When adding more than 20% Polydimethylsiloxane, dihydroxy terminated, the mechanical properties of the membrane decreased by a very large degree. We may ascribe this to the nonpolar chemical bonding of PDMS and the components giving rise to an improved microphase separation. These results indicated that PDMS H12MDI–PCDL-based TPUs have good tensile moduli and ultimate tensile stress (comparable to or even superior to some commercial polyurethane), even though a relatively large content of Polydimethylsiloxane, dihydroxy terminated could probably diminish their physical properties. The objective of this study was to prepare PDMS H12MDI–PCDL-based polyurethane samples with stable mechanical properties and good biocompatibility. By modifying them with different amount of PDMS, the effect of PDMS on the chemical structure, surface morphology, mechanical behavior and biocompatibility was investigated. The results demonstrated polyurethane with a soft segment partially replaced by PDMS could increase the biocompatibility while maintaining relatively high mechanical behavior. The Polydimethylsiloxane, dihydroxy terminated 10%-TPU sample with a Young’s modulus of 9.2  ±  1.2 MPa, tensile strength of 22.5  ±  2.7 MPa and elongation at break of 750%  ±  40% had the best biocompatibility, exhibiting great potential for usage in artificial vessels or other tissue engineering applications.

Polysiloxane foams containing hydroxyl-terminated polydimethylsiloxanes

Polymer foams have been attracting great interest because of their good properties, such as their light weight, low thermal conductivity, high specific surface area, and strong sound absorption. The polysiloxane foam materials exhibited a higher thermal stability than that of conventional polymer foam. It may be obtained from the linear polysiloxanes containing active functional groups. Polydimethylsiloxane, dihydroxy terminated (OH-PDMSs) are the basic component of an SIF material. It is usually synthesized by ring-opening polymerization of hexamethylcyclotrisiloxane or octamethylcyclotetrasiloxane (D4). Cross-linking is based on the polycondensation and polyaddition reaction in the presence of a catalyst. One of the processes occurs between the silanol groups and the Si–H groups of polymethylhydrosiloxane (PMHS) with the evolution of hydrogen. The balance between foaming and cross-linking was obtained by increasing the chain length of OH-PDMS. This process promoted the formation of enhanced cellular structure. The present work is performed to improve the thermal insulation and stability of SIF by controlling the chain length of Polydimethylsiloxane, dihydroxy terminated. This method is easy to operate and avoid the poor compatibility compared with the addition of inorganic particles into the polysiloxane matrix.[2]

The present work presented a method for improving the thermal stability and thermal insulation of polysiloxane foam by regulating the chain length of Polydimethylsiloxane, dihydroxy terminated. A series of SIF was prepared through foaming and cross-linking processes with different cross-linking densities. The balance between foaming and cross-linking was beneficial to produce the uniform cellular structure. The increase in chain length of OH-PDMS accompanied the increase in viscosity of the system, which also contributed to the change in the microstructure. The SIF prepared from the long-chain Polydimethylsiloxane, dihydroxy terminated displayed lower thermal conductivity than the short-chain products. The microstructure and foam density of the foam were both considered as factors that influenced the thermal conductivity of SIFs. However, cell microstructure was the main factor. The higher cell density and smaller cell size enhanced the contribution ratio of gases conduction to the total thermal conductivity. In addition, it interrupted the continuous solid conductivity through the cell wall and struts. The Tg decreased to −40.8 °C, which indicated that the low-temperature resistance of SIFs was enhanced. Although the silicone-based polymer exhibited a certain degree of flame retardancy, no significant improvement in flame retardancy was observed when the chain length of Polydimethylsiloxane, dihydroxy terminated was adjusted. The lower foam density and homogeneous cellular structure were beneficial to improve mechanical property.

Polydimethylsiloxane, dihydroxy terminated-modified epoxy resin

Epoxy resin (EP) constitutes a thermosetting plastic with attributes such as corrosion resistance, robust adhesion, sound chemical stability, and cost-effectiveness. It is evident that siloxane materials can enhance the hydrophobicity of epoxy resin and elevate the protective capabilities the coating. Consequently, in this study, Polydimethylsiloxane, dihydroxy terminated was selected for the modification of epoxy resin, with variations in its ratio to the epoxy resin. KH-550 was employed to enhanced the compatibility between Polydimethylsiloxane, dihydroxy terminated and epoxy resin. The investigation included an assessment of the mechanical properties, swelling degree, and water absorption rate of the HTPDMS/EP composite. Furthermore, the fracture morphology resulting from the tensile test was examined using scanning electron microscopy. Additionally, the coating properties, including impact toughness, adhesion grade, and WCA, were characterized. Furthermore, the polarization curve and electrochemical impedance spectrum (EIS) of the epoxy resin coatings were obtained within 3.5 wt% NaCl solutions at varying immersion durations.[3]

The modification of epoxy resin with Polydimethylsiloxane, dihydroxy terminated has proven to be successful. This modification has resulted in improved elongation at break and impact toughness while reducing pencil hardness. These changes can be attributed to the toughening effect of the Si-O-flexible segment present in HTPDMS. Furthermore, the crosslinking density of the composites gradually decreases with the addition of HTPDMS, leading to an increase in the swelling degree and water absorption rate. Additionally, the introduction of Polydimethylsiloxane, dihydroxy terminated imparts hydrophobicity to the coating; however, it also leads to a decrease in adhesion. The electrochemical results suggest that the coating exhibits the best protective performance when the ratio of EP to HTPDMS is 8:2. Excessive formation of island structures may negatively impact the properties of the composites and coatings.

References

[1]Zhu, Rong et al. “Influence of hydroxyl-terminated polydimethylsiloxane on high-strength biocompatible polycarbonate urethane films.” Biomedical materials (Bristol, England) vol. 12,1 015011. 9 Dec. 2016, doi:10.1088/1748-605X/12/1/015011

[2]Zhang C, Qu L, Wang Y, Xu T, Zhang C. Thermal insulation and stability of polysiloxane foams containing hydroxyl-terminated polydimethylsiloxanes. RSC Adv. 2018 Mar 8;8(18):9901-9909. doi: 10.1039/c8ra00222c. PMID: 35540826; PMCID: PMC9078707.

[3]Xie, Y., Du, X., Tian, Q., Dong, Y., & Zhou, Q. (2024). Investigation of hydroxyl-terminated polydimethylsiloxane-modified epoxy resin. Materials Chemistry and Physics, 313, 128822. https://doi.org/10.1016/j.matchemphys.2023.128822

You may like