基于双硫键和氢键协效的高性能自修复聚氨酯脲的研制

为解决自修复弹性体同时具有优异的力学性能和自修复性能的矛盾,首先将原料胱氨酸（CYS）进行甲酯化得到含双硫键的二胺扩链剂胱氨酸二甲酯（CDE）,然后以聚四氢呋喃醚二醇（PTMG）为软段,异佛尔酮二异氰酸酯（IPDI）和CDE为硬段,固定摩尔比为1∶3∶2,采用两步法制备了自修复聚氨酯脲（SH-PUU）弹性体,并对SH-PUU进行了红外光谱测试、拉曼光谱测试、力学性能测试、自修复性能测试、划痕修复微观形貌观察、应力松弛和动态力学性能测试。实验结果表明：SH-PUU的软段和硬段的玻璃化转变温度分别为-38.5℃和77.6℃,微相分离程度较高,SH-PUU具有良好的力学性能,拉伸强度为13.6MPa,断裂伸长率达531.3%;同时SH-PUU具有高效的自修复能力,试样在经过80℃修复2h后,基于拉伸强度的自修复效率达到97.1%,SH-PUU的力学性能和自修复性能达到较好的平衡。SH-PUU的高自修复能力是由动态双硫键和氢键协效增强引起的,其通过加热方式的自修复机理为：SH-PUU中的动态双硫键在80℃发生可逆交换反应,SH-PUU中的氢键在低于100℃时会重新形成。     

Effect of hydroxyl‐terminated poly(fluoroalkyl methacrylate) main‐chain length on the microphase separation of waterborne fluorinated polyurethane

Waterborne fluorinated polyurethanes (WFPUs) based on hydroxyl‐terminated poly(fluoroalkyl methacrylate)s (HTPFMAs) with different main‐chain lengths were synthesized. The structure of HTPFMA was characterized using ¹H NMR spectroscopy, measurements of hydroxyl values and gel permeation chromatography. The microstructures of WFPUs were investigated using Fourier transform infrared spectroscopy, which indicated that hydrogen bonding interactions in hard segments of WFPUs were enhanced by the introduction of HTPFMA and increased with increasing main‐chain length of HTPFMA. The results of X‐ray diffraction demonstrated that increasing the main‐chain length of HTPFMA resulted in an increase of crystallinity in hard segments. Differential scanning calorimetry revealed that the melting temperature of micro‐crystallites in hard segments and the microphase separation increased with an increase of HTPFMA main‐chain length. Dynamic mechanical analysis and scanning electron microscopy also confirmed that HTPFMA with longer main‐chain length can promote the extent of microphase separation of WFPUs between soft and hard domains. The mechanical properties of WFPUs were improved due to the increase of microphase separation with increasing HTPFMA main‐chain length. © 2018 Society of Chemical Industry     

Stepwise surface modification of mesoporous silica and its use in poly(urethane-urea) composite films

The compatibility between polymer matrix and filler is a vital issue in the fabrication of composites with desirable properties. To enhance the interfacial adhesion between matrix and filler, various surface modification treatments are applied. The objective of this study was to increase the affinity of silica and poly(urethane-urea)s (PUUs), thereby improving the mechanical properties of the resulting composites. Stepwise surface modification of mesoporous silica with amine-containing dendrimers was done. Various techniques were used to confirm the surface-modified structure during the stepwise reaction. Additionally, the N₂ adsorption–desorption method indicated a gradual reduction in surface area, pore diameter and pore volume of the particles, which warrants the gradual propagation of the dendrimers on the surface and also inside the pores. A type IV isotherm was obtained in this analysis. Two types of pre-synthesized PUUs were chosen for composite preparation containing the surface-modified silica with 0.5, 1, 2.5 and 5 wt% concentrations. Due to the high affinity of the dendrimers containing amine moieties on the particles with polyurethane, a proper dispersion of particles in the matrix was achieved based on scanning electron micrographs. Tensile measurements showed an increased Young's modulus and strength of polyurethane films as a result of addition of the particles. However, no significant improvement in the tensile performance of the composites was seen above 2.5 wt% particle loading due to some particle aggregations. © 2021 Society of Industrial Chemistry.     

Rheological investigation of microphase separation transition of polyurethane elastomer

A technique of linear viscoelasticity measurements coupling with temperature scanning was found effective in the detection of microphase separation transition (MST) and in the determination of MST temperature. The validity and accuracy of the technique were confirmed and reinforced by atomic force microscopy and differential scanning calorimetry (DSC). The technique was applied to a study of the MST of a series of 13 polyurethane (PU) elastomers based on mixed toluene diisocyanate (TDI), 1,4 butadiol, and poly(tetramethylene oxide) (PTMO) of two different molecular weights; the MST temperatures of the PU elastomer samples were measured. Although each of the 13 polymer samples had distinct hard segment content and used PTMO of different chain lengths, or mixed PTMO, the MST temperatures of the 13 samples formed a linear master curve when the MST temperature was plotted against the fraction of hard segment. The master curve indicated that the MST temperature is independent of the length and type of PTMO. It was also found that 2,4 TDI prevailing over its isomer 2,6 TDI played a dominant role in the MST of this series of PU elastomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2107–2112, 2007     

微相分离对聚氨酯弹性体耐热性能的影响研究

在聚氨酯弹性体固化过程中添加微相分离促进荆,对不同温度下的热失重分析（TGA）和力学性能高温保持率进行了对比分析,分析表明,添加了微相分离促进剂的聚氨酯弹性体耐热性能得到了提高。     

Biodegradable and thermostable synthetic hyperbranched poly(urethane-urea)s as advanced surface coating materials

Aliphatic hyperbranched poly(urethane-urea)s with different weight percentages of branch generating moiety were synthesized by a one pot A₂ + BC₂ approach. Isophorone diisocyanate was used as the A₂ type monomer, while a tri-functional dihydroxyamine compound synthesized from ?-caprolactam and diethanol amine acted as the BC₂ monomer. Evidence supporting the hyperbranched structure of the synthesized poly(urethane-urea) was obtained from ¹H NMR spectra. FTIR study confirmed the nature and extent of hydrogen bonding present in this novel macromolecule. A Gaussian band fitting procedure of the IR band at amide-I region showed that the extent of hydrogen bonding increases with the increase of weight percentage of the tri-functional compound. The tensile strength, elongation at break, impact resistance, scratch hardness and gloss followed an increasing trend with the same. The thermal degradation of the hyperbranched poly(urethane-urea) was found to be dependent on the weight percentage of the BC₂ type moiety. The kinetics of thermal degradation studied by the Ozawa method showed that the activation energy required for thermal degradation of hyperbranched polymer is higher than its linear polyurethane analog. The synthesized polymer was found to be biodegradable by Pseudomonas aeruginosa bacteria. The study showed superiority of the hyperbranched structure over the linear one. Thus the results indicated the potential usage of the studied hyperbranched poly(urethane-urea) as an advanced surface coating material.     

微相分离促进剂对MDI型聚氨酯弹性体的耐热性能影响研究

在聚氨酯弹性体固化过程中添加微相分离促进剂,通过差示扫描量热分析（DSC）和动态力学性能测试（DMA）表明,微相分离促进剂的加入提高了4,4′-二苯基甲烷二异氰酸酯（MDI）弹性体的微相分离程度;通过不同温度下的热失重分析（TGA）和力学性能高温保持率对比分析表明,添加了微相分离促进剂的聚氨酯弹性体耐热性能得到了提高。     

Viscoelastic behaviour of self‐assembling polyurethane and poly(vinyl alcohol)

The rheological behaviour of polyurethane (PU) and poly(vinyl alcohol) (PVA) was investigated in aqueous solution and the hydrogel state. The dependence of viscosity on polymer concentration is discussed. The formation of supramolecular structures induced by temperature increase or shear conditions was evidenced. In PU solutions, as temperature increases, a self‐assembling process occurs due to hydrogen bonding and hydrophobic interactions determining a thermoreversible hydrogel formation. In creep and recovery tests, the weak PU network presents high elasticity only at low shear stress (below 10 Pa); it recovers only 15%–20% of strain above 40 Pa and the hydrogel structure fails at high shear stress (above 150 Pa). Also, PU hydrogel is not able to recover its structure after being submitted to successive low and high deformations. In PVA solutions, a shear induced aggregation was observed at 37 °C. PVA hydrogels obtained by the freezing–thawing method present high elasticity and stability due to the strong polymer–polymer interactions established between the polymer chains. Physical networks based on PU/PVA mixtures synergistically combine the characteristics of the two polymers, showing high elasticity when a shear stress up to 3000 Pa is applied during the creep test followed by a fast recovery of the hydrogel structure after exhibiting successive levels of deformation (self‐healing ability). Therefore, these hydrogels are suitable materials for tissue engineering applications. © 2019 Society of Chemical Industry     

Novel dendritic-poly(urethane-urea) hybrid thin films from hydrogen bond rich dendrons

Hydrogen bond rich segmented poly(urethane-urea) was synthesized from methylene diphenylisocyanate (MDI) and three generations of polyurea-malonamide dendrons as hard segment and polycaprolactone diol as soft segment for thin film applications. The prepared polymers were characterized using spectroscopic, microscopic and thermal analyses. The formation of urethane linkage during the prepolymer reaction and the urea linkage between prepolymer and the dendrons is confirmed by Fourier transform infrared (FTIR) spectroscopy and ¹H nuclear magnetic resonance (NMR) spectroscopy. FTIR shows the presence of hydrogen bonding of –NH groups with both urethane carbonyl group from hard segment and the ether group from the soft segment. However, the phase mixing of hard and soft segments decreases with the higher generation dendrons, as evidenced from FTIR. This observation was confirmed by phase images of the atomic force microscopy (AFM). The coating when applied to clean steel substrates via dip coating reveals uniform, dense and essentially defect free morphology. The work demonstrates that the mechanical properties of the hybrid thin films are dependent on the generation of the dendrons and provides a platform for surface engineering with tunable elastic modulus.     

小分子扩链剂对醇溶性聚氨酯性能的影响

采用异佛尔酮二异氰酸酯(IPDI)、聚醚二元醇( N220)以及不同结构的小分子二元醇扩链剂为主要原料,合成了一系列具有不同结构的醇溶性聚氨酯.示差扫描量热和热重测试显示,以一缩二乙二醇为扩链剂的聚氨酯Tg最低,耐热性最差;以乙二醇、1,4-丁二醇、己二醇为扩链剂的聚氨酯Tg依次上升;耐热性能依次降低透射电镜测试表明,...     

Glycerol-modified poly(vinyl alcohol)/poly(ethylene glycol) self-healing hydrogel for artificial cartilage

Poly(vinyl alcohol) (PVA) hydrogels have shown potential applications in bionic articular cartilage due to their tissue-like viscoelasticity, good biocompatibility and low friction. However, their lack of adequate mechanical properties is a key obstacle for PVA hydrogels to replace natural cartilage. In this study, poly(ethylene glycol) (PEG) and glycerol were introduced into PVA, and a PVA/PEG–glycerol composite hydrogel was synthesized using a mixing physical crosslinking method. The mechanical properties, hydrophilicity and tribological behavior of the PVA/PEG–glycerol hydrogel were investigated by changing the concentration of glycerol in PEG. The results showed that the tensile strength of the hydrogel reached 26.6 MPa at 270% elongation at break with 20 wt% of glycerol plasticizer, which satisfied the demand of natural cartilage. In addition, the excellent hydrophilicity of glycerol provides good lubricating properties for the composite gel under dry friction. Meanwhile, self-healing and cellular immunity assays demonstrated that the composite gel could have good self-healing ability and excellent biocompatibility even in the absence of external stimuli. This study provides a new candidate material for the design of articular cartilage, which has the potential to facilitate advances in artificial joint cartilage repair. © 2022 Society of Industrial Chemistry.     

Syntheses of poly(ethylene oxide) polyurethane ionomers

Sulfonated dimethyl fumarate (SDMF) was prepared with dimethyl fumarate (DMF) and sodium hydrogensulfite (NaHSO₃). Sodium sulfonate side‐chain poly(ethylene oxide) (SPEO) was synthesized by grafting sodium sulfonate onto the chain of PEO with molecular weights of 400, 600, 800, and 1000. SPEO was used subsequently in step‐growth polymerization to give a polyurethane ionomer (SPU). Samples were characterized by element analysis, FTIR, ¹H‐NMR, EDX mapping, X‐ray, gel permeation chromatography, and impedance analysis. The SPUs exhibited an amorphous structure. The maximum conductivity of the SPU was 1.02 × 10⁻⁶ S cm⁻¹ at the room temperature. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 184–188, 2000     

聚氨酯/聚甲基丙烯酸甲酯互穿网络的阻尼性能及相态

引言聚合物互穿网络体系由于在其形成过程中产生特殊的物理拓扑结构,使得该体系是一种永久缠结在一起的聚合物"合金"[1]。同时,由于构成该体系的聚合物组分往往不相容或部分相容,在其形成     

端羟基聚丁二烯丙烯腈改性水性聚氨酯的制备及性能研究

以端羟基聚丁二烯丙烯腈(HTBN)和聚己二酸-1,4丁二醇酯二醇(PBA)为软段,合成了阴离子型水性聚氨酯(WPU),并讨论了不同HTBN用量对WPU性能的影响。红外光谱表征了HTBN和WPU的结构;粒径、DSC、XRD、TG及拉伸测试表明:随着HTBN含量的增加,乳液的平均粒径、胶膜的拉伸强度和断裂伸长率呈先增加后降低的趋势,耐热性能得到明显提升,而结晶性却表现出略微的降低;当软段中HTBN质量分数为30%时,乳液平均粒径最大,为250 nm;当软段中HTBN质量分数为40%时,拉伸强度和断裂伸长率最高,分别为20.2 MPa和521%;而相比于WPU0,WPU2和WPU5的结晶度仅从26.1%降低到24.9%和19.5%。     

Collagen immobilization on poly(ethylene terephthalate) and polyurethane films after UV functionalization

An attractive alternative method to add new functionalities such as biocompatibility due to the micro- and nanoscaled modification of surfaces is offered by UV-modified polymers. The aim of this study was to evaluate the effect of the UV light functionalization on two polymers, poly(ethylene terephthalate) (PET) and polyurethane (PU) films, by means of atomic force microscopy (AFM), Fourier transform infrared–attenuated total reflectance (FTIR–ATR), and contact angle measurements. Thus, the UV-irradiation activates the polymers surface by breaking some chemical bonds and generation of new functional groups on the surface. This process can be controlled by the irradiation time. The topography provides the formation of superposed ‘nap’ and ‘wall-type’ structures on both untreated and treated samples. The surface parameters were found to depend on the polymer films before and after irradiation. The immobilization of collagen on PET surface was confirmed by X-ray photoelectron spectroscopy measurements and for PU surface was proved by FTIR–ATR. First technique suggests an increase of the nitrogen content at longer UV exposure time, and the second one reveals the appearance of the protein Amide I band. Supplementary, AFM measurements clearly revealed the presence of collagen attached on the polymer surface. Thus, these new UV-irradiated polymers are promising materials in our further attempts to obtain new biofunctionalized surfaces.     

Synthesis and characterization of poly(methylene disulfide) and poly(ethylene disulfide) polymers in the presence of a phase transfer catalyst

Poly(methylene disulfide) and poly(ethylene disulfide) were synthesized from the polycondensation of methylene dichloride and ethylene dichloride monomers, respectively, in the presence of benzyltriethylammonium chloride as a phase transfer catalyst. The structures of the synthesized polysulfides were confirmed via the elemental analysis, attenuated total reflectance Fourier transform infrared spectroscopy and X-ray diffraction techniques. Moreover, the thermal behaviors of synthesized poly(methylene disulfide) and poly(ethylene disulfide) were characterized using differential scanning calorimetry and thermogravimetric analysis methods. The synthesized poly(methylene disulfide) and poly(ethylene disulfide) have molecular weights of about 2262 and 2863 g/mol, respectively. In addition, the polymers have crystalline structures absorbed in the amorphous sections. However, the d-spacing of polymers’ crystalline parts was different. Moreover, poly(methylene disulfide) and poly(ethylene disulfide) have a two- and one-step degradation behavior, respectively.     

Miscibility of segmented polyurethane/poly(vinyl chloride) blends

Miscibilities of segmented polyurethanes (SPUs) and poly(vinyl chloride) (PVC) or functionalized poly(vinyl chloride) (FPVC) were studied with dynamic mechanical analysis, differential scanning calorimetry, and X‐ray diffraction. Mechanical properties of the blends were also studied with tensile measurements. The miscibility of the blends depended greatly on the hard‐segment content of SPU and the existence of the functional groups. The combination of SPU with a low hard‐segment content and PVC with functional groups made the blend system miscible. Moreover, controlling the blend composition of SPU/FPVC allowed us to modify the mechanical properties of SPU, where the elongation at break was multiplied without a significant change in its tensile strength. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3022–3029, 2001     

有机硅/丁二醇扩链剂混合比对混合大二醇基聚氨酯弹性体的性能影响

以α,ω-双(γ-羟丙基)聚二甲基硅氧烷(BHPDMS)和聚氧四甲基二醇(PHMO)混合大二醇为软链段;以1,4-丁二醇(BDO)为主要扩链剂,1,3-双(4-羟丁基)-1,1,3,3-四甲基二硅氧烷(BHTD)为次级扩链剂,所有试样中硬链段均由4,4'-二苯基甲烷二异氰酸酯(MDI)和混合扩链剂所构成,且w(硬链段)=40%;采用两步溶液聚合法制备混合大二醇基芳香聚氨酯(PU)弹性体。通过力学性能测试、差示扫描量热法(DSC)和动力学热分析法(DMTA),研究了混合扩链剂中n(BDO)/n(BHTD)比值对该PU弹性体性能的影响。结果表明,当n(BDO):n(BHTD)=3:2时,所得PU弹性体具有优异的综合性能;引入BHTD扩链剂后,破坏了硬链段的有序性。     

Application of thermal methods in the characterisation of poly(urethane-urea)s formed by reaction injection moulding

Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) have been used in conjunction with tensile testing and transmission electron microscopy (TEM) to characterise novel segmented poly(urethane-urea) (PUU) network materials formed by reaction injection moulding (RIM). Materials were based on a modified liquid 4,4′-diphenylmethane diisocyanate and a polyether triol in admixture with one of three hindered aromatic diamines: 3,5-diethyltoluene diamine (DETDA); methylene-bis-2,6-diisopropylaniline (MMIPA); methylene-bis-(2-methyl-6-isopropylaniline) (MMIPA). The materials ranged from tough translucent elastomers to opaque brittle plastics depending on the chemical nature and weight fraction of the hard segments (HS). DSC and DMTA studies showed the PUU materials to be phase-separated; this was confirmed by TEM and tensile testing. The soft-segment glass transition temperatures (DSC and DMTA) were independent of composition but varied with diamine structure. Hard-segment glass transition temperatures could only be evaluated by DMTA and no evidence of crystallinity was found by thermal methods or by wide angle x-ray diffraction. Heat capacity measurements and DMTA suggested that some degree of phase mixing had occurred, to a greater extent in the DETDA and MDIPA systems. Phase inversion was observed by DMTA and confirmed at ～55% hard-segment content for DETDA systems by tensile testing.     

Preparation and characterization of conducting poly(diphenylamine) entrapped polyurethane network electrolyte

Composites of thermoplastic polyurethane (TPU) with poly(diphenylamine) (PDPA) were prepared by entrapping diphenylamine (DPA) molecules into the matrix of TPU and polymerizing DPA within the TPU matrix. Swelling rate of the parent TPU and the composites in 1M LiClO₄ in propylene carbonate solution were compared to understand the influence of the presence of PDPA in the composite in altering the morphology, conductivity, and electrolyte behavior. The nitrogen atoms in the PDPA interact and are likely to form hydrogen bonding with the carbonyl and ether groups in TPU. As a result, different morphology, thermal, and impedance behavior were witnessed for the composites in comparison to TPU. Results from differential scanning calorimetry, scanning electron microscopy (SEM), thermogravimetric analysis, and ac impedance measurements were obtained as supporting evidences. An increase in glass transition temperature for the composite in comparison to TPU infers the increase in phase mixing of soft and hard segment of TPU. The SEM micrograph shows the presence of fibrillar morphology of PDPA molecules in the composite. The ionic conductivity of the swelled composite was 1‐fold higher than that of pure TPU. A schematic representation showing the interaction of PDPA molecules with TPU is presented. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 611–617, 2006