Poly[( N-Acylimino)ethylene] Derivatives for Advanced Materials

2009 ◽  
Vol 21 (5) ◽  
pp. 596-607 ◽  
Author(s):  
Geta David ◽  
Bogdan C. Simionescu
Keyword(s):  
Phenyl Isocyanate ◽  
Chain Extender ◽  
Advanced Materials ◽  
Inorganic Component ◽  
Poly Ethylene Oxide ◽  
Hard Segments ◽  
Segmented Polyurethanes ◽  
Poly Ethylene ◽  
A Chain ◽  
Tetramethylene Oxide

New segmented polyurethanes containing soft and hard segments of different polarity and hydrophilicity, based on 4,4′-methylenebis-(cyclohexyl isocyanate, 4,4′-methylenebis-(phenyl isocyanate) and poly(tetramethylene oxide) or poly(ethylene oxide) were prepared including poly[( N-acylimino) ethylene] sequences as a chain extender. They were comparatively characterized by spectral, thermal and mechanical techniques. Some preliminary investigations on their nanocomposites with montmorillonite as an inorganic component are presented.

Rheology of Thermoplastic Polyurethanes

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Rheological Behavior ◽  
Thermoplastic Polyurethane ◽  
Complete Characterization ◽  
Chain Extender ◽  
Reaction Sequence ◽  
Molecular Weights ◽  
Soft Segments ◽  
Hard Segments ◽  
A Chain ◽  
Long Chain

Thermoplastic polyurethane (TPU) has received considerable attention from both the scientific and industrial communities (Hepburn 1982; Oertel 1985; Saunders and Frish 1962). Applications for TPUs include automotive exterior body panels, medical implants such as the artificial heart, membranes, ski boots, and flexible tubing. Figure 10.1 gives a schematic that shows the architecture of TPU, consisting of hard and soft segments. Hard segments, which form a crystalline phase at service temperature, are composed of diisocyanate and short-chain diols as a chain extender, while soft segments, which control low-temperature properties, are composed of difunctional long-chain polydiols with molecular weights ranging from 500 to 5000. The soft segments form a flexible matrix between the hard domains. TPUs are synthesized by reacting difunctional long-chain diol with diisocyanate to form a prepolymer, which is then extended by a chain extender via one of two routes: (1) by a dihydric glycol chain extender or (2) by a diamine chain extender. The most commonly used diisocyanate is 4,4’-diphenylmethane diisocyanate (MDI), which reacts with a difunctional polyol forming soft segments, such as poly(tetramethylene adipate) (PTMA) or poly(oxytetramethylene) (POTM), to produce TPU, in which 1,4-butanediol (BDO) is used as a chain extender. There are two methods widely used to produce TPU: (1) one-shot reaction sequence and (2) two-stage reaction sequence. The reaction sequences for both methods are well documented in the literature (Hepburn 1982). It should be mentioned that MDI/BDO/PTMA produces ester-based TPU. One can also produce ether-based TPU when MDI reacts with POTM using BDO as a chain extender. TPUs are often referred to as “multiblock copolymers.” In order to have a better understanding of the rheological behavior of TPUs, one must first understand the relationships between the chemical structure and the morphology; thus, a complete characterization of the materials must be conducted. The rheological behavior of TPU depends, among many factors, on (1) the composition of the soft and hard segments, (2) the lengths of the soft and hard segments and the sequence length distribution, (3) anomalous linkages (branching, cross-linking), and (4) molecular weight.

scholarly journals Novel Water Loving Coatings (WLC) Lubricious and Durable Guidewires

2017 ◽  
Author(s):  
Peter A. Edwards ◽  
Michael Price ◽  
Nick Nimchuk ◽  
Jeff Mahon
Keyword(s):  
Phenyl Isocyanate ◽  
Structure Property ◽  
Poly Ethylene Glycol ◽  
Water Dispersible ◽  
Structure Property Relationships ◽  
Soft Segments ◽  
Hard Segments ◽  
Poly Ethylene ◽  
Hydrophilic Coatings ◽  
Glycol Methyl Ether

Hydrophilic coatings applied to guidewires or catheters, lower friction of the device thus improves handling and reduces damage to the vessel walls during access, delivery and retrieval. Peripheral guidewires typically consist of a polymer jacket, basecoat and topcoat. The polymer jacket is highly radiopaque for fluoroscopy visualization. Basecoat adheres to the polymer jacket and hydrophilic topcoat. Basecoat and topcoat play important roles towards coating device durability and lubricity. Water Loving Coatings (WLC) are the first developed 510(k) clearance guidewires utilizing epoxy polyurethane technology. Coatings are non-hemolytic and non-cytotoxic. WLC are advances toward glycidyl carbamate (GC) resins. Linear Glycidyl Carbamates have shown excellent flexibility based off structure property relationships [1]. Water dispersible GC (WD-GC) oligomers have been prepared by additions of poly(ethylene glycol) methyl ether (m-peg) to isocyanurate and biuret, then end capped with glycidol [2]. WLC technologies are lubricious and durable water dispersible polyurethane or polyurea glycidyl carbamates [3]. Modified Hyaluronate with WD-GC oligomers have shown increases in lubricity of Guidewires when used with a catheter [4]. WLC coatings have been applied to a micro-wire to reduce endothelial mechanical lining damage [5]. Common thermoplastic urethanes (TPU), similar to WLC morphology, used in the medical industry, are: Biomer and Lubrizol’s Pellethane®, Tecoflex™ and Estane™. Biomer consists of 4,4′-Methylenebis(phenyl isocyanate) (MDI), Ethylenediamine (EDA), and Polytetramethylene diol (Poly THF). Pellethane consists of MDI, 1,4-Butanediol (BDO) and Poly THF. Tecoflex consists of 4-4′-methylenebis (cyclohexyl isocyanate) (H12MDI), BDO and Poly THF. Medical grade Estane is an ester of adipic acid with BDO for soft segments and MDI and BDO for hard segments. TPU structure and morphology dictates polymeric properties.

scholarly journals Influence of Hard Segment Content and Diisocyanate Structure on the Transparency and Mechanical Properties of Poly(dimethylsiloxane)-Based Urea Elastomers for Biomedical Applications

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 212
Author(s):  
Natascha Riehle ◽  
Kiriaki Athanasopulu ◽  
Larysa Kutuzova ◽  
Tobias Götz ◽  
Andreas Kandelbauer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Biomedical Applications ◽  
Hard Segment ◽  
Phenyl Isocyanate ◽  
In Vitro Cytotoxicity ◽  
Chain Extender ◽  
Elongation At Break ◽  
Hard Segment Content ◽  
Hard Segments

The effect of hard segment content and diisocyanate structure on the transparency and mechanical properties of soft poly(dimethylsiloxane) (PDMS)-based urea elastomers (PSUs) was investigated. A series of PSU elastomers were synthesized from an aminopropyl-terminated PDMS (M¯n: 16,300 g·mol−1), which was prepared by ring chain equilibration of the monomers octamethylcyclotetrasiloxane (D4) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). The hard segments (HSs) comprised diisocyanates of different symmetry, i.e., 4,4′-methylenebis(cyclohexyl isocyanate) (H12MDI), 4,4′-methylenebis(phenyl isocyanate) (MDI), isophorone diisocyanate (IPDI), and trans-1,4-cyclohexane diisocyanate (CHDI). The HS contents of the PSU elastomers based on H12MDI and IPDI were systematically varied between 5% and 20% by increasing the ratio of the diisocyanate and the chain extender APTMDS. PSU copolymers of very low urea HS contents (1.0–1.6%) were prepared without the chain extender. All PSU elastomers and copolymers exhibited good elastomeric properties and displayed elongation at break values between 600% and 1100%. The PSUs with HS contents below 10% were transparent and became increasingly translucent at HS contents of 15% and higher. The Young’s modulus (YM) and ultimate tensile strength values of the elastomers increased linearly with increasing HS content. The YM values differed significantly among the PSU copolymers depending on the symmetry of the diisocyanate. The softest elastomer was that based on the asymmetric IPDI. The elastomers synthesized from H12MDI and MDI both exhibited an intermediate YM, while the stiffest elastomer, i.e., that comprising the symmetric CHDI, had a YM three-times higher than that prepared with IPDI. The PSUs were subjected to load–unload cycles at 100% and 300% strain to study the influence of HS morphology on 10-cycle hysteresis behavior. At 100% strain, the first-cycle hysteresis values of the IPDI- and H12MDI-based elastomers first decreased to a minimum of approximately 9–10% at an HS content of 10% and increased again to 22–28% at an HS content of 20%. A similar, though less pronounced, trend was observed at 300% strain. First-cycle hysteresis among the PSU copolymers at 100% strain was lowest in the case of CHDI and highest in the IPDI-based elastomer. However, this effect was reversed at 300% strain, with CHDI displaying the highest hysteresis in the first cycle. In vitro cytotoxicity tests performed using HaCaT cells did not show any adverse effects, revealing their potential suitability for biomedical applications.

A biodegradable copolymer from coupling poly(pdioxanone) with poly(ethylene succinate) via toluene-2,4- diisocyanate

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiu-Li Wang ◽  
Si-Chong Chen ◽  
Yu-Hua Zhang ◽  
Ke-Ke Yang ◽  
Yu-Zhong Wang
Keyword(s):  
Oxidative Degradation ◽  
Crystallization Rate ◽  
Chain Extender ◽  
Thermal Oxidative Degradation ◽  
The Novel ◽  
H Nmr ◽  
Melting Temperatures ◽  
Diffraction Peaks ◽  
Poly Ethylene ◽  
A Chain

AbstractPoly(p-dioxanone) (PPDO) and poly(ethylene succinate) (PES) prepolymers were reacted together using toluene-2,4-diisocyanate (TDI) as a chain extender to produce high molecular weight of chain-extended products of PPDO and PES (PPDOES) in a suitable reaction condition. The novel biodegradable polymers were characterized by 1H-NMR, DSC, POM and WAXD. DSC measurement shows that PPDOES has only one Tg, which means that PPDO has good compatibility with PES. Beside this, the glass transition temperatures and the melting temperatures of PPDOES increased with the increase of PES content. The crystallization rate of PPDOES was slower than that of PPDO as confirmed by DSC and POM. The diffraction peaks of PPDOES appear at the same 2θ angles as that of homopolymers, suggesting that PPDO and PES segment of the chainextended products reserve their own crystallization form. The results of thermal oxidative degradation show that chain-extended products have better thermal stability than PPDO.

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