Polycaprolactone Diol Research Articles

ROS-responsive polyurethane fibrous patches loaded with methylprednisolone (MP) for restoring structures and functions of infarcted myocardium in vivo

Reactive oxygen species (ROS) play an important role in the pathogenesis of numerous diseases including atherosclerosis, diabetes, inflammation and myocardial infarction (MI). In this study, a ROS-responsive biodegradable elastomeric polyurethane containing thioketal (PUTK) linkages was synthesized from polycaprolactone diol (PCL-diol ), 1,6-hexamethylene diisocyanate (HDI), and ROS-cleavable chain extender. The PUTK was electrospun into fibrous patches with the option to load glucocorticoid methylprednisolone (MP), which were then used to treat MI of rats in vivo. The fibrous patches exhibited suitable mechanical properties and high elasticity. The molecular weight of PUTK was decreased significantly after incubation in 1 mM H2O2 solution for 2 weeks due to the degradation of thioketal bonds on the polymer backbone. Both the PUTK and PUTK/MP fibrous patches showed good antioxidant property in an oxidative environment in vitro. Implantation of the ROS-responsive polyurethane patches in MI of rats in vivo could better protect cardiomyocytes from death in the earlier stage (24 h) than the non ROS-responsive ones. Implantation of the PUTK/MP fibrous patches for 28 days could effectively improve the reconstruction of cardiac functions including increased ejection fraction, decreased infarction size, and enhanced revascularization of the infarct myocardium.

Synthesis and characterization of novel poly(urethane-urea) elastomers based on 1,3-propanediol bis(4-aminobenzoate) as chain extender

This paper presents the study of new polymer materials based on polycaprolactone diol and hexamethylene diisocyanate, containing urethane and urea groups which are bound both through flexible ether chains as well as through rigid benzene rings belonging to the chain extender structure (1,3-propanediol bis(4-aminobenzoate)). The structure of the chain extender determines the ability of the polymer matrix to perform physical interconnections. A range of cross-linkers with different flexible to rigid structures cross-linkers (propane-1,2,3-triol, castor oil, 1,2,3-benzentriol, 4,5-bis(hydroxymethyl)-2-methylpyridin-3-ol) were used in order to obtain chemical bonds between the polymer chains. The structure and properties of the prepared poly(urethane-urea) were characterized by Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetry (TG). FTIR measurements showed a decrease in mobility within the hard segment with the increase in chain extender content. DMA analysis revealed a secondary relaxation towards the rubbery transition. Poly (urethane-urea) elastomers obtained on the basis of 1,3-propanediol bis (4-aminobenzoate) showed good heat resistance at up to 300 °C and excellent mechanical properties with breaking strength of 65 MPa.

Poly(ethylene glycol)-sheddable reduction-sensitive polyurethane micelles for triggered intracellular drug delivery for osteosarcoma treatment

BackgroundThe survival rate of osteosarcoma therapy still lags behind overall cancer therapies due to the intrinsic or acquired drug resistance. Developing novel drug delivery systems that may overcome drug resistance would greatly facilitate osteosarcoma therapy. MethodsPoly(ethylene glycol) (PEG)-sheddable reduction-sensitive polyurethane (SS-PU-SS-PEG) was synthesized using a disulfide-containing polycaprolactone diol as the hydrophobic block and a cystamine-functionalized PEG as the hydrophilic block. SS-PU-SS-PEG micelles were then prepared to load the anti-tumor drug Doxorubicin (DOX) in order to achieve triggered intracellular drug delivery to improve the efficacy of osteosarcoma therapy. ResultsWhen DOX was used as a model drug, the drug-loaded SS-PU-SS-PEG micelles were about 82∼94 nm in diameter and exhibited good stability in phosphate buffer saline (PBS). The micelles could release about 80% DOX in a quantitative fashion within 5 hours under a reductive environment. The intracellular drug release of DOX-loaded SS-PU-SS-PEG micelles increased upon incubation with Saos-2 cells in vitro. The micelles had good biocompatibility. In vitro, DOX-loaded SS-PU-SS-PEG micelles showed significant antitumor activity toward Saos-2 cells, which was close to that of free DOX. In vivo, DOX-loaded SS-PU-SS-PEG micelles exhibited better antitumor activity than free DOX. ConclusionFindings from this study suggest that the SS-PU-SS-PEG micelles could achieve well-controlled triggered drug release in a reduction environment and could therefore improve the antitumor efficacy of osteosarcoma therapies. Translation potential of this articleIn this study we developed PEG-sheddable reduction-sensitive polyurethane micelles (SS-PU-SS-PEG), which were able to achieve well-controlled triggered release of anti-tumor drug Doxorubicin (DOX) in an intracellular reduction environment. DOX-loaded SS-PU-SS-PEG micelles markedly improved the antitumor efficacy in a Saos-2 cells-bearing xenograft tumor model. Therefore, such micelles might be used as a novel drug delivery system for osteosarcoma treatment.

Composite films obtained from a waterborne biopolyurethane. Incorporation of tartaric acid and nanocellulose

Unmodified castor oil (CO) and tartaric acid (TA), a dihydroxy acid that can be obtained from various by-products of the grape processing to wine, were used in order to obtain bio-based waterborne polyurethanes (WBPUs). Isophorone diisocyanate (IPDI) was incorporated to the formulation to obtain transparent films. The effect of the incorporation of polycaprolactone diol (PCL), a biodegradable diol was investigated in order to increase the flexibility of the WBPU. Additionally, cellulose nanocrystals (CNC) were used as bio-reinforcement for these polyurethanes (thus, increasing the use of bio resources). The final neat and composite material films were characterized by ATR-FTIR, XRD, DMA and TGA. The addition of PCL in the polyurethane formulation was confirmed by FTIR and led to the decrease of the Tg of the films, thus to a more flexible material. CNC addition resulted in an increase of the storage modulus of the material, at all the temperatures tested. CNCs interact and generate a three-dimensional network of the reinforcement (>2 wt.%), improving the ability of the films to maintain structural integrity when they were immersed in water.

Functional Properties of Poly(Trimethylene Terephthalate)-Block-Poly(Caprolactone) Based Nanocomposites Containing Graphene Oxide (GO) and Reduced Graphene Oxide (rGO).

This work reports a study on the influence of graphene oxide (GO) and reduced graphene oxide (rGO) on the functional properties of poly(trimethylene terephthalate)-block-poly(caprolactone) (PTT-block-PCL-T) (75/25 wt.%/wt.%) copolymer, obtained from dimethyl terephthalate (DMT), 1,3-biopropanediol and polycaprolactone diol (PCL) via in situ polymerization. The article presents, if and how the reduction of graphene oxide, in comparison to the non-reduced one, can affect morphological, thermal, electrical and mechanical properties. SEM examination confirms/reveals the homogeneous distribution of GO/rGO nanoplatelets in the PTT-block-PCL-T copolymer matrix. More than threefold increase in the value of the tensile modulus is achieved by the addition of 1.0 wt.% of GO and rGO. Moreover, the thermal conductivity and thermal stability of the GO and rGO-based nanocomposites are also improved. The differential scanning calorimetry (DSC) measurement indicates that the incorporation of GO and rGO has a remarkable impact on the crystallinity of the nanocomposites (an increase of crystallization temperature up to 58 °C for nanocomposite containing 1.0 wt.% of GO is observed). Therefore, the high performances of the PTT-block-PCL-T-based nanocomposites are mainly attributed to the uniform dispersion of nanoplatelets in the polymer matrix and strong interfacial interactions between components.

Influence of chitosan/1,4-butanediol blends on the thermal and surface behavior of polycaprolactone diol-based polyurethanes

This current study aims to study of the thermal behavior of the polyurethane elastomers (PUEs) by varying blends of 1, 4-butanediol and chitosan (CS) into the backbone of polyurethane (PU). The polycaprolactone diol (PCL) was used as a macrodiol while a mixture of CS and 1, 4-butanediol was reacted to extend the polymer. For the preparation of NCO-endcapped polyurethane prepolymer; one equivalent of PCL was reacted with three equivalents of toluene diisocyanate (TDI). The obtained pre-polymer was further extended with CS and 1, 4-butanediol (2 mol) individually and with different blends. The characterization of the structure was determined using FTIR and NMR spectroscopy. The glass transition temperature of prepared polyurethanes was measured by differential scanning calorimetry (DSC). The results obtained showed that, the thermal behavior of PUs was enhanced as the CS contents were increased in the PU backbone. The crystalline behavior of CS increased the hydrophobicity of the prepared PUs. Moreover; the water absorption, contact angle, swelling behavior, work of water adhesion and surface free energy of the synthesized PUs were affected with the addition of chitosan. Finally, it has been concluded resultant chitosan based PU has a potential for biomedical implant i.e., non-absorbable suture.

Preparation and characterization of biodegradable polyurethane composites containing oyster shell powder

In this study, natural oyster shell (OS) powder was used to reinforce polyurethane (PU) to fabricate OS powder/PU (OS/PU) composites. First, polycaprolactone diol, 4,4′-diphenylmethane diisocyanate, and 1,4-butanediol (1,4-BD) were utilized, respectively, as a soft segment, hard segment, and chain extender for PU. Next, the aforementioned chemicals were placed in the solvent N,N-dimethylacetamide (DMAc) to react with each other and form PU. Finally, OSP was added to the PU to form biodegradable OS/PUs. FTIR analysis showed that –NCO functional groups underwent a complete reaction, and X-ray diffraction analysis showed that OS characteristic crystallization peaks emerged when 2θ = 17.9°, 29.3°, and 34.0°. The TGA, DSC, and DMA showed that increases in OS content elevated PU decomposition temperature, glass transition temperature, and dynamic glass transition temperature. Antibacterial tests showed that increases in the OS content enhanced the antibacterial properties of OS/PUs against Staphylococcus aureus and Escherichia coli.

Flexible and Tough Cellulose Nanocrystal/Polycaprolactone Hybrid Aerogel Based on the Strategy of Macromolecule Cross-Linking via Click Chemistry

Cellulose nanocrystal (CNC) aerogel suffers from inherent brittleness, owing to the rigidity of crystals and the limited mobility between individual crystals. Conventional small molecule based cross-linking improves the toughness of CNC aerogel, but can hardly improve its flexibility. In this work, a macromolecule-based click cross-linking strategy with polycaprolactone diol as the cross-linker is employed to fabricate the CNC-PCL hybrid aerogel with enhanced toughness and flexibility. The molar ratio of CNC/PCL and the concentration of hydrogel are studied as the two key factors greatly affecting the mechanical performance of CNC-PCL aerogel. The resulted CNC-PCL hybrid aerogels show the highest compressive strength of 595 ± 100 kPa when the molar ratio of CNC/PCL is 1:0.1 (CP-0.1) and the highest shape recovery rate of 96.3 ± 2.5% when the molar ratio of CNC/PCL is 1:0.25 (CP-0.25). The surface polarity of CNC-PCL aerogel behaves as amphipathic due to the introduction of hydrophobic PCL. The thermal sta...

Monte Carlo simulation of an associating fluid model to describe polymerization in polycaprolactone diols: The role of attractive sites of variable range

In this work we study the clustering of hard spheres (HS) with associating square-well (SW) sites of variable range as a model of polymerization process, like the ring-opening polymerization of the ϵ-caprolactone. We present a systematic Monte Carlo (MC) computer simulation study of the effects of the interaction parameters on the cluster morphology, characterized by the fractal dimension, and compared with experimental results for the poly(ϵ-caprolactone). The cluster morphology depends on the length and energy scales of the system and both can be related to the intrinsic properties of propagating species.

Functionalized polyester-based materials as UV curable adhesives

UV curable adhesives offer major advantages in comparison to other polymeric based adhesive systems, such as fast-curing rate and control of the polymerization heat evolution, being ideal for application on damaged tissues.Herein, functionalized polymers were prepared by modifying polycaprolactone diol (PCL) with an isocyanate-functional unsaturated acrylic ester, Laromer® 9000, using two different proportions. These functionalized materials were chemically/physically characterized and, after the addition of a biocompatible photoinitiator (Irgacure® 2959), were crosslinked by UV light irradiation. Such procedure allows the obtention of flexible transparent films. Films’ properties such as swelling, hydrolytic degradation, thermal stability, surface energy and adhesive capacity were evaluated. Furthermore, to assess the applicability of the films in biomedical applications, their haemocompatibility and biocompatibility were determined using human dermal fibroblasts as model.

Promoted Osteoconduction of Polyurethane-Urea Based 3D Nanohybrid Scaffold through Nanohydroxyapatite Adorned Hierarchical Titanium Phosphate.

The lack of optimal physiological properties, bacterial colonization, and auto-osteoinduction, are the foremost issues of orthopedic implantations. In terms of bone healing, many researchers have reported the release of additional growth factors of the implanted biomaterials to accelerate the bone regeneration process. However, the additional growth factor may cause side effects such as contagion, nerve pain, and the formation of ectopic bone. Thus, the design of an osteoconductive scaffold having excellent biocompatibility, appropriate physicomechanical properties, and promoted auto osteoinductivity with antibacterial activity is greatly desired. In this study, 2D rodlike nanohydroxyapatite (nHA) adorned titanium phosphate (TP) with a flowerlike morphology was synthesized by a hydrothermal precipitation reaction. The nanohybrid material (nHA-TP) was incorporated into the synthesized polycaprolactone diol and spermine based thermoplastic polyurethane-urea (PUU) via in situ technique followed by salt leaching to fabricate the macroporous 3D polymer nanohybrid scaffold (PUU/nHA-TP). Structure explication of PUU was performed by NMR spectroscopy. The synthesized nanohybrid scaffold with 1% nHA-TP showed 67% increase of tensile strength and 18% improved modulus compared to the pristine PUU via formation of H-bonding or dative bonds between the metal and the amide linkage of the polyurethane or polyurea. In vitro study showing improved cell viability and proliferation of the seeded cell revealed the superior osteoconductivity of the nanohybrid scaffold. Most importantly, the in vivo experiments revealed a significant amount of bone regeneration in the nanohybrid scaffold implanted tibial site compared to the pristine scaffold without any toxic effect. Introduction of the minute amount of titanium phosphate within the adorned nHA promotes the osteoconductivity significantly by the capability of forming coordinate bonds of the titanium ion. Depending on the mechanical, physicochemical, in vitro characteristics, and in vivo osteoconductivity, the PUU/nHA-TP nanohybrid scaffold has great potential as an alternative biomaterial in bone tissue regeneration application.

Bio-based UV curable polyurethane acrylate: Morphology and shape memory behaviors

Smart bio-based shape memory polymers with high performance and fast response have the exciting potential to meet the growing need in biomedical applications.In this study, novel fast response UV-curable shape memory polyurethane acrylates (SMPUAs) comprising polycaprolactone diols (PCL-Diol), hexamethylene diisocyanate (HDI) and hydroxy-methyl methacrylate (HEMA) were synthesized by two-step bulk polymerization. Two series of PUAs with almost the same amount of hard segment content (HSC) were prepared with varying soft-segment molecular weight (2000, 3000, and 4000 g/mol) and different molar ratios of constituents. A mono-functional reactive diluent was used to control HSC and reduce the viscosity. Morphological characterization revealed nanoscale phase separation in SMPUAs. An increase in soft segment molecular weight was accompanied by an increase in the degree of microphase separation, crystallinity, and stiffness. The results indicated that shape memory behavior of PUAs was affected substantially by soft segment crystallinity and formation of stable ordered hard domains. The versatility of our SMPUAs was further reflected in good shape memory performance (higher than 97% fixity and recovery) with fast response as well as tunable transition temperature.

Diselenide linkage containing triblock copolymer nanoparticles based on Bi(methoxyl poly(ethylene glycol))-poly(ε-carprolactone): Selective intracellular drug delivery in cancer cells

Redox-responsive diselenide bond containing triblock copolymer Bi(mPEG-SeSe)-PCL,Bi(mPEG-SeSe)-PCL was developed for specific drug release in cancer cells. Initially, ditosylated polycaprolactone was prepared via the reaction between polycaprolactone diol (PCL-diol) and tosyl chloride (TsCl). Next, Bi(mPEG-SeSe)-PCL was synthesized via the reaction between ditosylated polycaprolactone and sodium diselenide initiated poly (ethylene glycol) methyl ether tosylate. The synthesized amphiphilic triblock copolymer could self-assemble into uniform nanoparticles in aqueous medium and disassemble upon redox stimuli. The Bi(mPEG-SeSe)-PCL nanoparticles showed a DOX loading content of 5.1 wt% and a loading efficiency of 49%. In vitro drug release studies showed that about 62.4% and 56% of DOX was released from the nanoparticles during 72 h at 37 °C in PBS containing 2 mg/mL (6 mM) GSH and 0.1% H2O2, respectively, whereas only about 30% of DOX was released in PBS under the same conditions. The cell viability (MTT assays) results showed that the synthesized material was biocompatible with above 90% cell viability, and that the DOX-loaded Bi(mPEG-SeSe)-PCL nanoparticles had a high antitumor activity against HeLa cells and low antitumor activity against HaCaT cells, following a 24-h incubation period. Three-dimensional (3D) spheroids of HeLa cells were established for the evaluation of localization of the DOX-loaded nanoparticles into spheroids cells and the successfully inhibition of 3D tumor spheroid growth. The results indicated that the synthesized material Bi(mPEG–SeSe)-PCL was biocompatible and it could be a potential candidate for anticancer drug delivery system.

Reduction of fluorescence resonance energy transfer by space control between quantum dots via direct bonding of reactive ligands to the polymer matrix for color conversion films

Fluorescence resonance energy transfer (FRET) between quantum dots (QDs) is one of main mechanisms that cause efficiency to drop in photoluminescence (PL) applications. In this work, we reduced FRET by controlling the distance between the QDs via chemical reactions between the QD ligands and long-chain linkers. The oleic acid ligands of the QDs were replaced with ligands containing reactive alcohol groups without any degradation in the quantum yield by a one-pot reaction. The alcohol groups of the QD ligands were reacted with polycaprolactone diol, which acted as a spacer, and tris(isocyanatohexyl)cyanurate to form cross-linked urethane bonds. The interconnected QD film showed 26% higher quantum efficiency and 19% longer PL decay time than that of a conventional film in which the QDs were randomly embedded in PMMA. The interconnection of the designed QD and the long spacer with the cross-linker is believed to prevent FRET between QDs and enhance the quantum yield of the QD films.

Bio‐Based Polyurethanes from Microbially Converted Castor Oil

AbstractBio‐based new polyurethanes (PU) were synthesized from microbially converted castor oil. Castor oil was used as a raw material to synthesize 7,10,12‐trihydroxy‐8(E)‐octadecenoic acid (TOD) by the strain Pseudomonas aeruginosa PR3. Subsequently, hexamethylene diisocyanate (HMDI) was used in different ratios and reacted with TOD to produce new PU. Fourier transform‐infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gas chromatography/mass spectrometry were used to confirm the identity of TOD. Differential scanning calorimetry, thermogravimetric analysis, and tensile property testing were used to investigate the thermal and mechanical properties of PU. PU synthesized based on TOD had a tensile strength of 45.4 MPa with low elongation at break of 8.16% at an isocyanate/hydroxyl ratio of 2.0. To modify the properties of PU, TOD was blended separately with polyethylene glycol or polycaprolactone diol at different weight ratios before reacting with HMDI. The modified polymer showed improved thermal stability and comparatively higher elongation at break. This is the first study demonstrating the conversion of castor oil into TOD that can be used stand alone or as a blend for PU synthesis.

Agar plate-based screening methods for the identification of polyester hydrolysis by Pseudomonas species.

SummaryHydrolases acting on polyesters like cutin, polycaprolactone or polyethylene terephthalate (PET) are of interest for several biotechnological applications like waste treatment, biocatalysis and sustainable polymer modifications. Recent studies suggest that a large variety of such enzymes are still to be identified and explored in a variety of microorganisms, including bacteria of the genus Pseudomonas. For activity‐based screening, methods have been established using agar plates which contain nanoparticles of polycaprolactone or PET prepared by solvent precipitation and evaporation. In this protocol article, we describe a straightforward agar plate‐based method using emulsifiable artificial polyesters as substrates, namely Impranil® DLN and liquid polycaprolactone diol (PLD). Thereby, the currently quite narrow set of screening substrates is expanded. We also suggest optional pre‐screening with short‐chain and middle‐chain‐length triglycerides as substrates to identify enzymes with lipolytic activity to be further tested for polyesterase activity. We applied these assays to experimentally demonstrate polyesterase activity in bacteria from the P. pertucinogena lineage originating from contaminated soils and diverse marine habitats.

A simple and versatile method to tailor physicochemical properties of thermoplastic polyurethane elastomers by using novel mixed soft segments

Novel thermoplastic polyurethane elastomers (TPUs) were designed and synthesized using mixtures of poly (tetramethylene ether) glycol (PTMG) and polycaprolactone (PCL) diols as soft segments. Five block polyurethanes with different soft segment composition were studied in order to discover the impact of mixed soft segments on the properties of TPUs. The corresponding properties of these polyurethanes including phase transitions, morphology, microphase separation, hydrogen bonding, rheological and mechanical were investigated by experimental methods. Molecular dynamics simulation was also used to evaluate dynamic of hard and soft segments, hydrogen bonding and segmental interactions at atomic level. Successful synthesizing of the TPUs was evaluated by ATR-FTIR and 13C NMR spectroscopy. The results indicated that polyurethanes with higher PTMG content produce stronger hydrogen bonding, more solid like behavior, higher microphase separation and lower viscosity than polyurethanes with high PCL diol; however the most exciting outcome is the influence that mixed soft segments have on the microphase separation kinetics and mechanical properties. Isothermal and non-isothermal examinations have shown that using mixed soft segments accelerated the microphase separation process comparing samples with one type of polyols and sample containing equal compositions of each polyols has the fastest microphase separation kinetics. Microscopy images showed that this sample has the thread-like hard segment rich regions and its morphology differs from other samples. Mechanical property data indicated that the enhanced elongation at break and overall toughness of TPU at equal ratio of PCL/PTMG is highest in comparison with other samples.

Development of metformin chain extended polyurethane elastomers as bone regenerative films

In this study, novel elastomeric biodegradable bone regenerative films were developed from metformin (Met) and polyurethane (PU). Metformin was selected due to its osteogenic properties and proper chemical structure to react with PU prepolymer. Metformin was integrated into PU macromolecular structure as chain extender after the synthesis of PU prepolymer via condensation polymerization of polycaprolactone diol and hexamethylene diisocyanate. Chemical, thermal, viscoelastic properties of PU-Met films where characterized and discussed in terms of structure-property relationships. PU-Met films had Tg value around −45 °C and showed superior viscoelastic properties under 1 Hz and 10 Hz tensile oscillation frequencies during dynamic mechanical analysis. On the 21st day of biodegradation studies, PU-Met films degraded 2.3 ± 0.1% and 37.8 ± 4.2% in oxidative and enzymatic media, respectively. Cell-material interactions of elastomeric films were investigated by proliferation (MTT assay), alkaline phosphatase activity (ALP), calcium depositions (Alizarin Red Quantification) and morphological evaluations (SEM). Presence of metformin in PU formulation increased MC3T3-E1 attachment, proliferation and calcium deposition.

Ecofriendly Reduction of Methylene Blue with Polyurethane Catalyst

A number of physical, chemical, and biological technologies have been developed to address the issue of synthetic dyes in wastewater. One of the important chemical methods involves reduction of these stringent pollutants into less hazardous products. In this study, a cross-linked polyurethane foam (CPUF) was prepared from toluene diisocyanate (TDI), tetraethylenepentamine (TEPA), and polycaprolactone diol (PCL; Mw: 1000 g/mole). To avoid harmful reducing agents, ecofriendly reduction of methylene blue (MB) was executed with CPUF as catalyst where ascorbic acid and fresh juice extracts were applied as reducing agents. The FTIR and SEM analysis confirmed the chemical composition and porous morphology of CPUF, respectively. The 100% reduction of MB was recorded in just 15 minutes with ascorbic acid and CPUF, while similar result was obtained in 37 minutes in blank experiment composed of only MB and ascorbic acid. Thus, catalytic role of CPUF in reduction process was proved. Fresh fruit extracts also participated in the reduction process, but rate of reaction was accelerated in the presence of CPUF. The reusability study of the catalyst supported its stability and efficiency. All the successful reduction processes followed 1st-order kinetics with highest apparent rate constant for ascorbic acid. Furthermore, phytotoxicity evaluation proved safe reduction of MB with 60% germination index. Hence, it can be concluded that catalytic role of CPUF has been established with safe and biodegradable reducing agents which can be extended to other redox processes.

Preparation and Rheology of Isocyanate Functionalized Graphene Oxide/Thermoplastic Polyurethane Elastomer Nanocomposites

Using monomer-functionalized nanofiller to prepare polymeric nanocomposites is a promising strategy toward achieving enhanced performance. In this study toluene-2,4-diisocyanate (TDI), one of the monomers used for synthesizing polyurethane, was covalently functionalized on graphene oxide (GO) and then the functionalized GO (TDI-GO) was polymerized with polycaprolactone diol (PCL) via in-situ polymerization, leading to chemically linked polyurethane nanocomposites through the covalent bonds between the isocyanate groups on GO and the hydroxyl-terminated PCL. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and dispersion experiments of the nanofillers demonstrated that the TDI was successfully grafted onto the GO. The rheological properties were investigated to establish the structure-property relationships of the nanocomposites. The storage moduli (G’), loss moduli (G”) and complex viscosity (η*) of the samples increased monotonically with TDI-GO content, which is attributed to the strong polymer-filler interactions and the effective dispersion of the nanofillers. Additionally, the tan δ variation with frequency, the intersection of G’ and G”, Han plots, van Gurp-Palmen plots and Cole-Cole plots all showed that the incorporation of TDI-GO decreased the degree of microphase separation and improved the elastic properties of the nanocomposites. We suggest this is related to the enhanced interactions between the polymer and nanofillers, which strongly restricted the mobility and relaxation of the polymer chains.