Prepolymer Of Poly Research Articles

Feasible self-healing CL-20 based PBX: Employing a novel polyurethane-urea containing disulfide bonds as polymer binder

Damages generated in functional materials can deteriorate their performance and shorten their lifetime, endowing the materials with self-healing ability is expected to resolve this problem. In this work, a novel energetic composite refers to CL-20 based PBX, which can self-heal its mechanical damage under a mild condition, was designed and prepared via incorporating disulfide bonds into the polymeric binder. The highly efficient self-healing polyurethane-urea containing disulfide bonds (DSPU) was synthesized by using the prepolymer of poly(caprolactone) diol (PCL-diol) with isophorone diisocyanate (IPDI) as the main-chain to achieve good mechanical toughness, then cross-linking with bis(4-aminophenyl) disulfide (APD) to gain the superior reversibility. The CL-20 based PBX using this DSPU as binder can evidently self-heal its inner damage, i.e. micro-crack, after heating at 60 °C for several hours, and the strength of the damaged sample after Brazilian test can also be recovered to more than 70% of the pristine value.

Preparation and Characterization of Isosorbide-Based Self-Healable Polyurethane Elastomers with Thermally Reversible Bonds.

Polyurethane (PU) is a versatile polymer used in a wide range of applications. Recently, imparting PU with self-healing properties has attracted much interest to improve the product durability. The self-healing mechanism conceivably occurs through the existence of dynamic reversible bonds over a specific temperature range. The present study investigates the self-healing properties of 1,4:3,6-dianhydrohexitol-based PUs prepared from a prepolymer of poly(tetra-methylene ether glycol) and 4,4′-methylenebis(phenyl isocyanate) with different chain extenders (isosorbide or isomannide). PU with the conventional chain extender 1,4-butanediol was prepared for comparison. The urethane bonds in 1,4:3,6-dianhydrohexitol-based PUs were thermally reversible (as confirmed by the generation of isocyanate peaks observed by Fourier transform infrared spectroscopy) at mildly elevated temperatures and the PUs showed good mechanical properties. Especially the isosorbide-based polyurethane showed potential self-healing ability under mild heat treatment, as observed in reprocessing tests. It is inferred that isosorbide, bio-based bicyclic diol, can be employed as an efficient chain extender of polyurethane prepolymers to improve self-healing properties of polyurethane elastomers via reversible features of the urethane bonds.

Novel synthesis of high‐molecular‐weight prepolymer of poly(p‐phenylene benzoxazole) in ionic liquids

Using ionic liquids (ILs) as the reaction solvent for the synthesis of prepolymer polyamide of poly(p‐phenylene benzoxazole) (PBO) was investigated. The optimum condition of prepolymer preparation was determined in ILs. A series of 1,3‐dialkylimidazolium ILs were used to be the reaction media of the polycondensation. The relationship between the molecular weight of prepolymer and the structure of ILs was analysed by changing the structure of the cation and species of anion of ILs. In order to prove the feasibility of the transformation, the prepolymer was used to prepare PBO in polyphosphoric acid media, and the conversion process was analyzed. The spinnability of the PBO solution was explored by the preparation of PBO fibers. The basic mechanical properties of PBO single fiber were tested. In a word, using 1,3‐dialkylimidazolium ILs as the reaction solvents was feasible for the synthesis of high‐molecular‐weight PBO prepolymer, which could be a promising PBO preparation method.

Novel elastomeric fibrous networks produced from poly(xylitol sebacate)2:5 by core/shell electrospinning: Fabrication and mechanical properties

Fabrication of nonlinear elastic materials that resemble biological tissues remains a challenge in biomaterials research. Here, a new fabrication protocol to produce elastomeric fibrous scaffolds was established, using the core/shell electrospinning technique. A prepolymer of poly(xylitol sebacate) with a 2:5mol ratio of xylitol:sebacic acid (PXS2:5) was first formulated, then co-electrospun with polyvinyl alcohol (PVA – 95,000Mw). After cross-linking of core polymer PXS2:5, the PVA shells were rinsed off in water, leaving a porous elastomeric network of PXS2:5 fibres. Under aqueous conditions, the PXS2:5 fibrous scaffolds exhibited stable, nonlinear J-shaped stress–strain curves, with large average rupture elongation (76%) and Young׳s modulus (~1.0MPa), which were in the range of muscle tissue. Rupture elongation of PXS2:5 was also much higher when electrospun, compared to 2D solid sheets (45%). In direct contact with cell monolayers under physiological conditions, PXS2:5 scaffolds were as biocompatible as those made of poly-l-lactic acid (PLLA), with improvements over culture medium alone. In conclusion, the newly developed porous PXS2:5 scaffolds show tissue-like mechanical properties and excellent biocompatibility, making them very promising for bioengineering of soft tissues and organs.

Liquid–Liquid Interfacial Nanomolding

Nanoscale interfaces that form between two immiscible liquids can be harnessed to create patterned nanoarray structures. Pattern formation is achieved with nanodrop effusion of an uncured prepolymer of polydimethylsiloxane by mechanically compressing the wrinkle-patterned mold, followed by UV-assisted molding of the nanodrops with a different prepolymer of poly(urethane acrylate), resulting in the formation of ordered nanohole arrays over a large area.

Controllable Synthesis and Electroluminescence Property of Water-Sol ZnCdTe Alloy for Light-emitting Diodes

By changing the stabiliz er system and synthesis temperature, ZnCdTe alloy have been controllably synthesized in aqueous solution using a simple route. A high synthesis temperature leads to nanoparticles growth using thioglycolic acid (TGA) as the stabilizer, whereas a low synthesis temperature promotes the form of nanorods using TGA and L-Cysteine(L-Cys) as the stabilizer. The different morphologies of samples have been characterized by transmission electron microscopy (TEM). The optical properties of the obtained ZnCdTe nanorods and nanoparticles have been investigated by photoluminescence (PL) spectroscopy with different refluxing times. We have also demonstrated electroluminescence (EL) property from heterostructure device fabricated with the prepolymer of Poly(p-phenylenevinylene) (PPV ) and ZnCdTe alloyed nanocrystals. Current density of device with ZnCdTe alloy in emitting layer is obviously increased.

Long term in vivo degradation and tissue response to photo‐cross‐linked elastomers prepared from star‐shaped prepolymers of poly(ε‐caprolactone‐co‐D,L‐lactide)

Long term in vivo degradation, and tissue response to, cylindrical elastomers made of photo-cross-linked star-poly(epsilon-caprolactone-co-D,L-lactide) triacrylate were investigated through subcutaneous implantation in rats. The elastomers were prepared via UV initiated crosslinking of prepolymers of equimolar amounts of monomers; a high crosslink density elastomer (ELAST 1250) was prepared from a prepolymer of 1250 Da and a low crosslink density elastomer (ELAST 7800) was prepared from a prepolymer of 7800 Da. The elastomers were characterized using cross-polarization magic angle spinning solid state (13)C NMR and attenuated total reflectance fourier transform infrared spectroscopy. The progress of the in vivo degradation process was followed by employing SEM, uniaxial tensile, mass loss, water uptake, and sol content measurements. The rate of in vivo degradation was faster than the rate of in vitro degradation for both ELAST 1250 and ELAST 7800. Long term in vivo degradation studies indicated that both elastomers undergo bulk hydrolysis along with surface erosion occurring due to the physiological environment. In the case of low cross-link density elastomers, the onset of mass loss was accompanied with an increase in both water uptake and sol content, whereas, in the case of high crosslink density elastomers, only the water uptake increased. This degradation pattern was due to crazing of the high crosslink density elastomers. ELAST 7800 cylinders were totally degraded, and ELAST 1250 cylinders had lost 80% of their mass, within 30 weeks. Aminor host reaction with minimal vascularity and inflammation was invoked, with a milder tissue response observed with more highly crosslinked cylinders.

Syntheses of new film-forming aromatic poly(amide-imide)s containing isoindoloquinazolinedione unit in the backbone: Poly(biphenylphthalicdianhydride-oxydianiline-4,4′-diamino-3′-carbamoyl-benzanilide) (poly(BPDA-ODA-DACB))

New film forming aromatic poly(amide-imide)s containing isoindoloquinazolinedione (IQ) unit in the backbone chain (polymerXIV) have been successfully synthesized by preparing prepolymers of poly(amic acid-carbonamide), followed by subsequent thermal cyclization of the prepolymers. 4,4′-Diamino-3′-carbamoylbenzanilide (DACB)V has been synthesized by reduction of 3′-carbamoyl-4′-amino-4-nitrobenzanilideIV. The prepolymers of poly(amic-acid-carbonamide) (polymersVII andVIII) which exhibit viscosities ranging from 1.4 to 1.7 dl/g have been prepared by a condensation polymerization of monomers such as BPDA, ODA, and DACB. PolymerXIV has been obtained by thermal cyclization of the polymersVII andVIII. During the thermal cyclization reaction, imide ring structure was first introduced and then transformed to the structure of IQ unit. The thermal degradation rate of the resultant polymers were influenced by the cleavage of amide bond but the final char yield was comparable to that of poly(BPDA-ODA).

Poly(ethylene glycol)-block-poly(butyl acrylate). I. Synthesis

Prepolymers of poly(ethylene oxide) (Pre-PEO) were synthesized by reacting azoisobutyronitrile (AIBN) with poly(ethylene glycol) (PEG), and their structures were characterized by IR and UV. The molecular weight of pre-PEO was related to the feed ratio and reaction time. These prepolymers can be used to prepare block copolymers—poly(ethylene oxide)-block-poly(butyl acrylate) (PEO-b-PBA) by radical polymerization in the presence of butyl acrylate (BA). Solution polymerization was a suitable technique for this step. The yield and the molecular weight of the product were related to the ratio of the prepolymer to BA, the reaction time, and temperature. GPC showed that the molecular weight increased with a higher ratio of BA to pre-PEO. The intrinsic viscosity of the copolymers was only slightly dependent on reaction time, but decreased at higher reaction temperatures, as did the amount of PBA homopolymer. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1667–1674, 1997

Synthesis and Hemocompatibilities of New Segmented Polyurethanes and Poly(urethane urea)s with Poly(butadiene) and Phosphatidylcholine Analogues in the Main Chains and Long-Chain Alkyl Groups in the Side Chains

Three new phospholipid diols, bis[2-(2-hydroxyethyldimethylammonio)ethyl]diethylene octadecylamine diphosphate (BDODP), bis[2-(2-hydroxyethyldimethylammonio)ethyl]diethylene hexadecylamine diphosphate (BDHDP), and bis[2-(2-hydroxyethyldimethylammonio)ethyl]diethylene dodecylamine diphosphate (BDDDP), together with 1,4-butanediol (BD) or ethylenediamine (ED) as chain extender were further incorporated into the prepolymer of poly(butadiene) glycol (PBD) and 4,4‘-methylenediphenyl diisocyanate (MDI). The bulk and surface characteristics of the resulting phospholipid segmented polyurethanes (SPUs) and segmented poly(urethane urea)s (SPUUs) were investigated by infrared (IR), gel permeation chromatography (GPC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA), and contact angle measurements. The mechanical properties were investigated by dynamic viscoelasticity. The hemocompatibilities of the new polymers were evaluated by plat...

Polyurethanes containing binaphthyl groups

AbstractPolyurethanes containing binaphthyl groups were synthesized by reaction of diisocyanates – 4,4'‐diphenylmethane diisocyanate (MDI), 2,4‐toluylene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) – with 2,2'‐(1,1'‐binaphthyl‐4,4'‐ylenedioxy)diethanol (3). The polyurethane obtained from 3 with MDI has an intrinsic viscosity [η]90DMSO90°C of 0,14 dl · g−1 and a melting point of 244 – 260°C, that from 3 with TDI has an [η]90°CDMSO of 0,12 dl · g−1 and a melting point of 181 – 191°C, and that from 3 with HDI has an [η]90°CDMSO of 0,11 dl · g−1 and a melting point of 222 – 241°C. These polymers were found to be crystalline. Segmented polyurethanes (SPU) from 3 with prepolymers of poly(tetramethylene glycol) (PTG), (M = 1079) and MDI or HDI (mole ratio PTG:MDI (or HDI) = 1:2) were also synthesized. The SPU from MDI has an intrinsic viscosity [η]90°CDMSO of 0,56 dl · g−1 and a melting point of 260–275°C, and that from HDI has an [η]90°CDMSO of 0,50 dl · g−1 and a melting point of 231 – 253°C. These polymers show slight crystallinity.