Characterization of polydimethylsiloxane–polyurethanes synthesized by graft or block copolymerizations

Synthesis and characterization of low surface energy thermoplastic polyurethane elastomers based on polydimethylsiloxane

Organosilicon modified polyurethane elastomers (Si-MTPUs) were synthesized in order to improve the anti-graffiti property of thermoplastic polyurethane elastomers (TPUs). Si-MTPUs were prepared from polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) as mixed soft segment, 1,4-butanediol (BDO) and imidazole salt ionic liquid N-glyceryl-N-methyl imidazolium chloride ([MIM_l,g]Cl) used as chain extender, and 4,4'-dicyclohexylmethane diisocyanate (HMDI). The structure, thermal stability, mechanical properties and physical crosslinking density of Si-MTPUs were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), mechanical test and low field nuclear magnetic resonance. Surface energy and water absorption were characterized by static contact angle test and water resistance test, and anti-graffiti and self-cleaning properties were characterized with water, milk, ink, lipstick, oily markers and spray paint. It was found that the mechanical properties of Si-MTPU-10 with the content of PDMS 10 wt% were optimized, with a maximum tensile strength of 32.3 MPa and elongation at break of 656%. Surface energy reached the minimum value of 23.1 mN m^-1 with the best anti-graffiti performance, which no longer decreased with the increase of PDMS contents. This work provides novel idea and strategy for the preparation of low surface energy TPUs.

Preparation and Properties of Hydrophobic Polyurethane Based on Silane Modification

Waterborne coatings have obtained more and more attention from researchers with increasing concerns in environmental protection, and have the advantages of being green, environmentally friendly and safe. However, the introduction of hydrophilic groups leads to lower hydrophobicity and it is difficult to meet the requirements of complex application environments. Herein, we proposed an optimization approach of waterborne polyurethane (WPU) with vinyl tris(β-methoxyethoxy) silane (A172), and it was found that the surface roughness, mechanical properties, thermal stability and water resistance of WPU will be increased to a certain extent with the addition of A172. Moreover, the hydrophobicity of the coating film is best when the silicon content is 10% of the acrylic monomer mass and the water contact angle reaches 100°, which could exceed two-thirds of the research results in the last decade. Therefore, our study can provide some theoretical basis for the research of hydrophobic polyurethane coatings.

Investigation of corrosion and thermal behavior of PU–PDMS-coated AISI 316L

Polydimethylsiloxane (PDMS) is widely used from biomedical to industrial applications due to its nontoxic, hydrophobic, and transparent characteristics. PDMS has good thermal and adhesion properties; however, its mechanical properties are comparatively weak. Therefore, PDMS is blended with various polymers to effectively improve its mechanical properties. In this study, polyurethane (PU)–polydimethylsiloxane (PDMS) blended coatings of different concentrations were applied on the AISI 316L stainless steel surface. Their effects on corrosion and tribocorrosion properties were investigated in Ringer’s solutions. The blended polymer coatings were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The thermal properties of samples were examined by TGA and DSC. The surface images and cross-sectional were investigated using scanning electron microscopy (SEM). Tribocorrosion tests were carried out at open circuit potential (OCP). It was determined that hydrophobicity and thermal stability of polymer coating increased, while corrosion resistance slightly decreased with the increasing PDMS concentration in the polymer blended. The friction coefficient of blends decreased as the PU concentration increased. As a result, it was determined that the polymer-coated samples containing up to 50% PDMS prevented corrosive wear under the OCP wear test in Ringer’s solutions.

Synthesis and Properties of Linear Polyether-Blocked Amino Silicone-Modified Cationic Waterborne Polyurethane

In this study, a waterborne polyurethane (WPU) is synthesized by using polytetramethylene ether glycol (PTMEG) to form the soft segment, 1,4-butanediol (BDO) as the chain extender, n-methyldiethanolamine (MDEA) as a hydrophilic chain extender, and isophorone diisocyanate (IPDI) to form the hard segment. Furthermore, the modified cationic WPU emulsion and its films are created through a reaction between the WPU and a linear polyether-blocked amino silicone (LEPS), which is an organosilicon compound that imparts flexibility. The properties of the structure and formed WPU films are then characterized by using Fourier transform infrared spectrometry, a thermogravimetric analysis, atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, as well as by measuring the water contact angle, testing the water absorption, etc. It is found that, with an increase in the LEPS content in the WPU, the particle size of the modified WPU emulsion is increased, the WPU films are more flexible, and the resistance of the modified WPU films to heat and water are increased, while the crystallinity is reduced. The polysiloxane chain segment, which is added to the LEPS-modified WPU emulsion, is significantly enriched on the surface of the modified WPU films, while there are no adverse effects of the LEPS-modified WPU emulsion on the adhesive force between the WPU and substrate. When the LEPS content of the WPU is 14.0 wt%, the modified WPU emulsion and film provide the best performance.

Reinforced poly(hydroxyurethane) thermosets as high performance adhesives for aluminum substrates

High performance adhesives for bare aluminum are prepared by reinforcing poly(hydroxyurethane) (PHU) thermosets with (functional) nanofillers and poly(dimethylsiloxane).

Well-defined polyurethane-graft-poly(N,N-dimethylacrylamide) copolymer with a controlled graft density and grafted chain length: synthesis and its application as a Pickering emulsion

Well-defined PU-g-PDMA graft copolymers with controlled graft densities and grafted chain lengths could be facilely synthesized by combining the polyaddition reaction with the RAFT polymerization.

Synthesis and Properties of Polypropylene Carbonate Polyol-Based Waterborne Polyurethane

Different kinds of anionic polyhydric alcohols water-borne polyurethane (WPU) emulsion and films were prepared by separately taking polypropylene carbonate polyol (PPC), polyethylene-1,4-buthylene adipate glycol (PBA) and polytetramethylene ether glycol (PTMG) with the same molecular weight as soft segment. Their structure and properties were characterized with Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), rigidity, adhesive power, contact angle and water absorption. Comparing their properties, it was found that the rigidity, adhesive power and water resistance of PPC WPU were similar to those of PBA WPU.

Rheological behaviour of thermoplastic poly(ester-siloxane)s

Two series of thermoplastic elastomers (TPES) based on poly(dimethylsiloxane), (PDMS) as the soft segment and poly(butylene terephthalate) (PBT) as the hard segment, were analyzed by dynamic mechanical spectroscopy. In the first TPES series the lengths of both hard and soft segments were varied while the mass ratio of the hard to soft segments was nearly constant (about 60 mass%). In the second series, the mass ratio of hard and soft segments was varied in the range from 60/40 to 40/60, with a constant length of soft PDMS segments. The influence of the structure and composition of TPESs on the rheological properties, such as complex dynamic viscosity, ?*, the storage, G?, and loss, G?, shear modulus as well as the microphase separation transition temperature, TMST, was examined. The obtained results showed that the storage modulus of the TPESs increased in a rubbery plateau region with increasing degree of crystallinity. The rheological measurements of TPESs also showed that a microphase reorganization occurred during the melting process. The microphase separation transition temperatures were in the range from 220 to 234 ?C. In the isotropic molten state, the complex dynamic viscosity increased with increasing both the content and lenght of hard PBT segments.