紫外光固化水性油墨及墨膜耐磨性能

传统紫外光固化(UV)油墨具有粘度低、固化速度快、应用范围广等优点。 但存在使用少量有机溶剂、交联程度低等缺陷。 本文通过自由基聚合制备的苯乙烯丙烯酸共聚物与甲基丙烯酸羟乙酯(HEMA)反应制备水性预聚物。 通过甲基丙烯酸缩水甘油酯(GMA)和乙二胺反应制备了含有四丙烯酸官能团的活性稀释剂。 最后,通过水性预聚物、活性稀释剂、光引发剂以及少量溶剂制备了UV光固化水性油墨。 探讨了光引发剂的种类和质量分数、预聚物的相对分子质量和质量分数、活性稀释剂的结构和质量分数对UV油墨的光固化速度以及耐磨度的影响。 当预聚物的数均相对分子质量为1.98×10⁵且质量分数为30%、光引发剂质量分数为4%、活性稀释剂的官能团数目为4且质量分数为40%的UV水性油墨的光固化速率为1 s,经50次磨损质量损失为9%。 该方法所制得的UV水性油墨可用于柔版印刷、凹印、数字印刷等。     

哌嗪-苯胺二环氧系感光性高分子的研究 Ⅰ.合成及其感光性

用哌嗪和N,N-二环氧丙基苯胺(苯胺二环氧)通过线型加成聚合反应,得到一种新型高分子。这种高分子与有机多卤化物所组成的感光体系,在近紫外光(300—400nm)的照射下,发色的同时交联固化。最低固化光量为78mJ·cm^-2。发色吸收峰初始为660nm,随曝光量增大,吸收增大,峰值向650nm俯移。所得蓝绿色图像可用稀酸显影。硫杂蒽酮类化合物是这些体系很有效的增感剂。     

Additive manufacturing of fire‐retardant ethylene‐vinyl acetate

Thermocompression (with also extrusion and injection molding) is a classical polymer shaping manufacturing, but it does not easily allow designing sophisticated shapes without using a complex mold, on the contrary to 3D printing (or polymer additive manufacturing), which is a very flexible technique. Among all 3D printing techniques, fused deposition modeling is of high potential for product manufacturing, with the capability to compete with conventional polymer processing techniques. This is a quite low cost 3D printing technique, but the range of filaments commercially available is limited. However, in some specific 3D printing processes, no filaments are necessary. Polymers pellets feed directly the printing nozzle allowing to investigate many polymeric matrices with no commercial limitation. This is of high interest for the design of flame‐retarded materials, but literature is scarce in that field. In this paper, a comparison between thermocompression and 3D printing processes was performed on both neat ethylene‐vinyl acetate (EVA) copolymer and EVA flame retarded with aluminum triHydroxyde (ATH) containing different loadings (30 or 65 wt%) and with expandable graphite (EG), ie, EVA/ATH (30 wt%), EVA/ATH (65 wt%), and EVA/EG (10 wt%), respectively. Morphological comparisons, using microscopic and electronic microprobe analyses, revealed that 3D printed plates have lower apparent density and higher porosity than thermocompressed plate. The fire‐retardant properties of thermocompressed and 3D printed plates were then evaluated using mass loss calorimeter test at 50 kW/m². Results highlight that 3D printing can be used to produce flame‐retardant systems. This work is a pioneer study exploring the feasibility of using polymer additive manufacturing technology for designing efficient flame‐retarded materials.     

Synthesis and properties of biodegradable copolymers based on 4,4′‐(adipoyldioxy)dicinnamic acid, 1,6‐hexanediol,and poly(ethylene glycol)s

4,4′‐(Adipoyldioxy)dicinnamic acid (CAC) was synthesized by a condensation of adipoyl chloride and 4‐hydroxycinnamic acid. The CAC6 copolymers were prepared by a high‐temperature solution polycondensation of a diacyl chloride of CAC, 1,6‐hexanediol (6), and poly(ethylene glycol) (PEG) in which the molecular weights of PEG are 1000, 2000, and 8300. Differential scanning calorimetric curves of the copolymers exhibited a glass‐transition temperature because of PEG moiety and two melting endotherms (T_m's); the one at the higher T_m was due to CAC6 moiety, and the other at the lower T_m was due to PEG moiety, suggesting that these copolymers are the block type. The incorporation of the PEG component decreased the tensile strength and initial modulus, but increased the elongation extremely. The enzymatic degradation was performed in phosphate buffer solution (pH 7.2) with Ps. cepacia lipase at 37 °C. The degradation rate of the copolymers increased significantly with an increasing content of PEG, which was correlated to the water absorption of the copolymers. All copolymers could undergo photocuring by ultraviolet (UV) light irradiation (λ > 280 nm) at ambient temperature, as examined by UV spectroscopy and solubility. The CAC6/E2000(50/50) film photocured for 3 min exhibited a good elastic property with a maximum tensile strength of 3.7 MPa and maximum elongation of 640%. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2930–2938, 2003     

Gel formation and photopolymerization during supramolecular self-assemblies of α-CDs with LA-PEG-LA copolymer end-capped with methacryloyl groups

A novel gelation occurs in water during supramolecular self-assemblies of α-cyclodextrins being threaded onto amphiphilic LA-PEG-LA copolymer end-capped with methacryloyl groups. The rheologic studies show that the gels are thixotropic and reversible. While exposed to UV irradiation with a photoinitiator added in advance, they can be photopolymerized in situ to give rise to chemically cross-linked biodegradable hydrogels with the markedly improved mechanical strength. The gels formed prior to and after UV irradiation are characterized using FTIR, ¹H NMR, WAXD and TGA techniques. The swelling ratio and in vitro degradation of the photocured hydrogels are also investigated. It appears that both physical and chemical gels have the potential to be used as injectable biomaterials.     

Vinylcarbonates and vinylcarbamates: Biocompatible monomers for radical photopolymerization

The last decade has seen a remarkable interest in the use of biocompatible and biodegradable polymers as scaffolds for tissue engineering. The fabrication of 3D scaffolds by lithography‐based additive manufacturing technology (AMT) represents an appealing approach. As poly(lactic acid), the state of the art biocompatible and biodegradable material, cannot be processed by these photopolymerization‐based techniques, it has so far been necessary to use selected (meth)acrylates. By developing new photopolymers based on vinyl carbonates and vinyl carbamates as a reactive group we have been able to avoid most of the disadvantages of classical (meth)acrylate‐based photopolymers. The new generation of biocompatible monomers show low cytotoxicity, have good storage stability, and are sufficiently photoreactive to be structured by lithography based AMT. The mechanical properties and rates of degradation of the polymers can be easily tuned over a broad range. Degradation results in the formation of nonacidic and nontoxic degradation products of low molecular weight that can be easily transported within the human body. Initial in vivo tests showed significant osseointegration of the 3D cellular scaffolds and no signs of implant rejection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and properties of photocurable biodegradable multiblock copolymers based on poly(ε‐caprolactone) and poly(L‐lactide) segments

Photocurable biodegradable multiblock copolymers were synthesized from poly(ε‐caprolactone) (PCL) diol and poly(L ‐lactide) (PLLA) diol with 4,4′‐(adipoyldioxy)dicinnamic acid (CAC) dichloride as a chain extender derived from adipoyl chloride and 4‐hydroxycinnamic acid, and they were characterized with Fourier transform infrared and ¹H NMR spectroscopy, gel permeation chromatography, wide‐angle X‐ray diffraction, differential scanning calorimetry, and tensile tests. The copolymers were irradiated with a 400‐W high‐pressure mercury lamp from 30 min to 3 h to form a network structure in the absence of photoinitiators. The gel concentration increased with time, and a concentration of approximately 90% was obtained in 90–180 min for all the films. The photocuring hardly affected the crystallinity and melting temperature of the PCL segments but reduced the crystallinity of the PLLA segments. The mechanical properties, such as the tensile strength, modulus, and elongation, were significantly affected by the copolymer compositions and gel concentrations. Shape‐memory properties were determined with cyclic thermomechanical experiments. The CAC/PCL and CAC/PCL/PLLA (75/25) films photocured for 30–120 min showed good shape‐memory properties with strain fixity rates and recovery rates of approximately 100%. The formation of the network structure and the crystallization and melting of the PCL segments played very important roles for the typical shape‐memory properties. Finally, the degradation characteristics of these copolymers were investigated in a phosphate buffer solution at 37 °C with proteinase‐k and Pseudomonas cepacia lipase. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2426–2439, 2005     

Novel 3D printed shape-memory PLLA-TMC/GA-TMC scaffolds for bone tissue engineering with the improved mechanical properties and degradability

The biodegradable substitution materials for bone tissue engineering have been a research hotspot. As is known to all, the biodegradability, biocompatibility, mechanical properties and plasticity of the substitution materials are the important indicators for the application of implantation materials. In this article, we reported a novel binary substitution material by blending the poly(lactic-acid)-co-(trimethylene-carbonate) and poly(glycolic-acid)-co-(trimethylene-carbonate), which are both biodegradable polymers with the same segment of flexible trimethylene-carbonate in order to accelerate the degradation rate of poly(lactic-acid)-co-(trimethylene carbonate) substrate and improve its mechanical properties. Besides, we further fabricate the porous poly(lactic-acid)-co-(trimethylene-carbonate)/poly(glycolic-acid)-co-(trimethylene-carbonate) scaffolds with uniform microstructure by the 3D extrusion printing technology in a mild printing condition. The physicochemical properties of the poly(lactic-acid)-co-(trimethylene-carbonate)/poly(glycolic-acid)-co-(trimethylene-carbonate) and the 3D printing scaffolds were investigated by universal tensile dynamometer, fourier transform infrared reflection (FTIR), scanning electron microscope (SEM) and differential scanning calorimeter (DSC). Meanwhile, the degradability of the PLLA-TMC/GA-TMC was performed in vitro degradation assays. Compared with PLLA-TMC group, PLLA-TMC/GA-TMC groups maintained the decreasing T_g, higher degradation rate and initial mechanical performance. Furthermore, the PLLA-TMC/GA-TMC 3D printing scaffolds provided shape-memory ability at 37 ℃. In summary, the PLLA-TMC/GA-TMC can be regarded as an alternative substitution material for bone tissue engineering.     

Modification and Characterization of Chitosan Films Using 3-trimethoxyl Silyl Propylmethacrylate

The biodegradable flexible chitosan film was prepared by solution casting. The physico-mechanical properties, polymer loading (PL), gel content and water uptake of the chitosan film were studied. The tensile strength (TS) and % elongation at break (Eb) of the uncured chitosan film were 7.0 (MPa) and 8%, respectively. Four formulations were developed using 3-trimethoxyl silyl propylmethacrylate (TSPMA) (varied from 10–80% by weight) in methanol along with photoinitator (Darocur-1664). The raw chitosan films were then soaked in the prepared formulations and cured under UV radiation at different intensities to improve the physico-mechanical properties of the films. TS for the photocured chitosan film was 28.0 (MPa) which was 4 times higher compared to the uncured chitosan film. This TS was obtained for the formulation containing 30% silane (TSPMA) at 24th UV pass for 4 min soaking time. The maximum PL of 45.1% was obtained for the same formulation at 24th UV pass for 4 min soaking time. The water uptake and gel content of the photocured chitosan films were also studied. The scanning electron micrographs of the photocured chitosan film showed smooth surface, compact and homogeneous structure.     

Physical Models from Physical Templates Using Biocompatible Liquid Crystal Elastomers as Morphologically Programmable Inks For 3D Printing

Advanced manufacturing has received considerable attention as a tool for the fabrication of cell scaffolds however, finding ideal biocompatible and biodegradable materials that fit the correct parameters for 3D printing and guide cells to align remain a challenge. Herein, a photocrosslinkable smectic-A (Sm-A) liquid crystal elastomer (LCE) designed for 3D printing is presented, that promotes cell proliferation but most importantly induces cell anisotropy. The LCE-based bio-ink allows the 3D duplication of a highly complex brain structure generated from an animal model. Vascular tissue models are generated from fluorescently stained mouse tissue spatially imaged using confocal microscopy and subsequently processed to create a digital 3D model suitable for printing. The 3D structure is reproduced using a Digital Light Processing (DLP) stereolithography (SLA) desktop 3D printer. Synchrotron Small-Angle X-ray Diffraction (SAXD) data reveal a strong alignment of the LCE layering within the struts of the printed 3D scaffold. The resultant anisotropy of the LCE struts is then shown to direct cell growth. This study offers a simple approach to produce model tissues built within hours that promote cellular alignment.     

聚合物基微纳米功能复合材料3D打印加工的研究

高分子材料3D打印加工可制备传统加工不能制备的形状复杂的高分子制件,是近年来发展很快的先进制造技术。但适用于3D打印加工的高分子材料种类少,结构功能单一,难以制备高分子功能器件。本文介绍了我们在聚合物基微纳米功能复合材料3D打印加工方面的研究工作:通过有机/无机杂化、固相剪切碾磨、超声辐照、分子复合等技术制备适合于选择性激光烧结(SLS)和熔融沉积成型(FDM)的聚合物基微纳米功能复合材料;实现了聚合物基微纳米功能复合粉体的SLS加工和功能复合丝条的FDM加工;研究了3D打印低维构建、层层叠加、自由界面成型、复杂固-液-固转变过程;建立了功能复合粉体球形化技术,发明了直接熔融挤出新型FDM打印机;制备了常规加工方法不能制备的数种形状复杂的功能器件,如尼龙11/钛酸钡压电器件、柔性聚氨酯/碳纳米管传感器、个性化人颌骨模型等,突破了传统加工难以制备复杂形状制品和目前3D打印难以制备功能制品的局限。     

Numerical characterization of ultraviolet ink fluid agglomeration and the surfactant effect in nanoinkjet printing

Ultraviolet (UV) ink is a major ink type used in additive manufacturing via 3D inkjet printing. A major challenge in nanoinkjet printing is ink agglomeration. Among the UV ink components, oligomers have the highest tendency to agglomerate which can agitate the stability and quality of the printing fluid and possibly lead to nanoscale nozzle clogging. In this work, the first numerical study on the UV ink fluid, UV ink is modeled by using dissipative particle dynamics to study mesoscale agglomeration. The constituents of the ink model are composed of polystyrene and polyethylene glycol as photopolymers, BZP as a photoinitiator, and SDS as a surfactant. Styrene is a prevalent and established commercial photopolymer in present 3D inkjet applications, while ethylene glycol is a photopolymer known to improve ink viscosity. The morphological characteristics of the UV ink are studied here, where the results for different models from four cases considered here show how the kind of photopolymers and their constituent ratios affect the agglomeration morphology of the fluidic system. The existence of both oligomers and monomers results in mutual morphological benefits against agglomeration, while the photoinitiator occurs between photopolymers. In addition, we find that the surfactant can reduce the average size of agglomeration and improve the dispersion uniformity by increasing the number of agglomerates. These results highlight the important role additives can play to prevent, reduce, and control various forms of agglomeration to achieve enhanced nanoinkjet printing quality. Copyright © 2017 John Wiley & Sons, Ltd.     

3D Printing of Silk Protein Structures by Aqueous Solvent‐Directed Molecular Assembly

Hierarchical molecular assembly is a fundamental strategy for manufacturing protein structures in nature. However, to translate this natural strategy into advanced digital manufacturing like three‐dimensional (3D) printing remains a technical challenge. This work presents a 3D printing technique with silk fibroin to address this challenge, by rationally designing an aqueous salt bath capable of directing the hierarchical assembly of the protein molecules. This technique, conducted under aqueous and ambient conditions, results in 3D proteinaceous architectures characterized by intrinsic biocompatibility/biodegradability and robust mechanical features. The versatility of this method is shown in a diversity of 3D shapes and a range of functional components integrated into the 3D prints. The manufacturing capability is exemplified by the single‐step construction of perfusable microfluidic chips which eliminates the use of supporting or sacrificial materials. The 3D shaping capability of the protein material can benefit a multitude of biomedical devices, from drug delivery to surgical implants to tissue scaffolds. This work also provides insights into the recapitulation of solvent‐directed hierarchical molecular assembly for artificial manufacturing.     

Functionalized acrylic polyhydroxy urethanes as molecular tool box for photocurable thermosets and 3D printing

Liquid urethane (meth)acrylates represent attractive components of photocurable thermosets for applications ranging from coatings and adhesives to 3D printing. Herein we tailor liquid polyfunctional urethane methacrylates (UMA) derived from acrylic polyhydroxy urethanes. Cyclic carbonate methacrylates react with diamines to form dihydroxy-functional urethane dimethacrylates. In an “one-pot” process the hydroxy groups are functionalized either by reaction with 2-isocyanatoethyl methacrylate (IEMA) or by esterification with methacrylic anhydride (MAA) and acetic anhydride (AA). The hydroxy group esterification substantially lowers the resin viscosity (26–156 Pa•s). Hydroxy functionalization with IEMA and MAA affords tetrafunctional methacrylates. The corresponding photo-cured thermosets exhibit higher crosslinking density and improved stiffness as reflected by increasing the Young's modulus from 2900 to 3700 MPa combined with increasing the glass temperature from 135 to 204°C. Hence, this facile molecular UMA design enables to control functionality and thermoset properties over a wide range and meets the demands of 3D printing applications.     

Synthesis and preparation of biodegradable and visible light crosslinkable unsaturated fumarate‐based networks for biomedical applications

Biodegradable polymers have currently attracted high interest as ideal carriers in drug delivery and tissue engineering applications. In situ forming devices based on these materials will synergistically provide the advantages of the customary prefabricated devices as well as ease of administration. To acheive these objectives, optically transparent and biodegradable macromers based on poly(ethylene glycol) and fumaric acid copolymers were synthesized using propylene oxide as a different proton scavenger to enhance in situ photocrosslinking capability. The macromers in different compositions were then photocured for 300 sec in the presence of a visible light initiator/accelerator couple and also a reactive diluent. Characterization of the macromers and the resulting networks were performed using different spectroscopic, chromatographic, physical, and thermal analysis techniques. The resulted shrinkage strain of the macromers upon photocuring was studied using the bounded disk technique, and initial shrinkage strain rates were obtained by numerical differentiation. Our results suggest that the compositions based on these unsaturated aliphatic polyesters are potentially useful to develop injectable, in situ photocrosslinkable carriers for drug and cell delivery applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Organically modified montmorillonite polymer nanocomposites for stereolithography building process

Novel photopolymerizable nanocomposite formulations, able to photopolymerize with a dual curing mechanism (cationic and radical), were developed, characterized and used in the stereolithography (SL) process for the construction of 3D objects with a very simple geometry. The influence of the presence of organically modified montmorillonite (OM) nanoparticles on the reactivity of the photopolymerizable liquid mixtures was firstly analyzed, as function of the amount of nanofiller, by photocalorimetric analysis (p‐DSC). The basal distance of OM before and after mixing with the photocurable formulation was characterized by X‐ray diffraction. Composites with higher content of OM show an intercalated structure. An exfoliated structure was instead observed in the composites with the lowest OM content, after photocuring in the SL apparatus. These results were also confirmed by the morphological analysis performed by SEM. The glass transition temperature of nanocomposites, photocured by stereolithography, was finally measured by TMA and DSC techniques, confirming that the photocurable formulation loaded with the lowest amount of OM presents improved properties than the unloaded formulation. Copyright © 2014 John Wiley & Sons, Ltd.     

Surface molecular characterisation of different epoxy resin composites subjected to UV accelerated degradation using XPS and ToF-SIMS

Epoxy resin composites reinforced with E-glass (E), 3D glass (3D) and carbon fibre (CF) were subjected to an intense UV and high temperature accelerated degradation environment. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to provide a molecular characterisation of the surface of the degraded composites. The response at the surface of the epoxy resin composites to oxidative degradation is influenced by the composite reinforcement type and characteristics. XPS results indicate that 3D resin composites exhibit more surface oxidation as a result of the accelerated degradation in comparison with E and CF composites. Principal components analysis (PCA) of the ToF-SIMS positive ion spectra showed that E and 3D resin composites suffered chain scission while CF composites suffered chain scission and cross-linking reactions as a result of the intense UV exposure. The extent of the surface oxidation, cross-linking/condensation reaction and loss of low molecular weight (lower than C₄H_x) aliphatic hydrocarbons may be indicated using PCA of both the ToF-SIMS positive and negative ion spectra. PCA also provides insight for proposing epoxy resin chain scission and oxidation reaction mechanisms.     

Novel thermosets obtained by UV‐induced cationic copolymerization of DGEBA with an spirobislactone

The photocuring process of the diglycidyl ether of bisphenol A (DGEBA) with the bislactone 1,6‐dioxaspiro[4,4]nonane‐2,7‐dione (s(γ‐BL)) was studied. Triarylsulfonium hexafluoroantimonate was employed as photoinitiator. FTIR/ATR was used to study the evolution of epoxy, lactone, and intermediate spiroorthoester groups to identify the different reactions that take place during the photocuring process. Photo‐DSC and DSC were used to study the thermal evolution of the photocuring process and to assess the T_g of the fully cured material. Thermogravimetric analysis (TGA) was used to determine the thermal stability of the fully cured material. The thermomechanical properties of the materials were investigated using dynamic mechanical‐thermal analysis. Shrinkage undergone during photocuring and gelation was studied with TMA. A strong influence of the photocuring temperature on the photocuring process of the DGEBA‐ s(γ‐BL) system was observed. Differences in the reactivity of the different species were observed with respect to the thermally cured system using ytterbium triflate as cationic thermal initiator. As a consequence, photocured materials exhibited a superior thermal stability and lower flexibility. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5446–5458, 2007     

Composite PLA/PEG/nHA/Dexamethasone Scaffold Prepared by 3D Printing for Bone Regeneration

3D printing has become an essential part of bone tissue engineering and attracts great attention for the fabrication of bioactive scaffolds. Combining this rapid manufacturing technique with chemical precipitation, biodegradable 3D scaffold composed of polymer matrix (polylactic acid and polyethylene glycol), ceramics (nano hydroxyapatite), and drugs (dexamethasone (Dex)) is prepared. Results of water contact angle, differential scanning calorimeter, and mechanical tests confirm that incorporation of Dex leads to significantly improved wettability, higher crystallinity degree, and tunable degradation rates. In vitro experiment with mouse MC3T3‐E1 cells implies that Dex released from scaffolds is not beneficial for early cell proliferation, but it improves late alkaline phosphatase secretion and mineralization significantly. Anti‐inflammation assay of murine RAW 264.7 cells proves that Dex released from all the scaffolds successfully suppresses lipopolysaccharide induced interleukin‐6 and inducible nitric oxide synthase secretion by M1 macrophages. Further in vivo experiment on rat calvarial defects indicates that scaffolds containing Dex promote osteoinduction and osteogenic response and would be promising candidates for clinical applications.     

3D printed PCL scaffold reinforced with continuous biodegradable fiber yarn: A study on mechanical and cell viability properties

In this study, poly (ε‐caprolactone) (PCL) scaffolds were printed and reinforced, simultaneously, with biodegradable poly glycolic acid (PGA) suture yarn, as a continuous reinforcing fiber, in the Fused Deposition Modeling (FDM) 3D printing process. Albeit PCL is a suitable material for biomedical applications, its low mechanical properties, and low degradation rate have limited its usage. A biocompatible suture yarn was used as the reinforcing material to enhance the mechanical properties and biodegradation characteristics, via an innovative method of continuous fiber embedding in the FDM process. The reinforced PCL samples were 3D printed with the setting porosity value of 60% and 0°/60°/120° lay-down pattern. The mechanical and biological properties of the scaffolds were tested to prove the effectiveness of the produced scaffolds for bone substitute purposes. Mechanical properties assessments showed that with a 22 vol.% suture yarn content in the 3D printed PCL scaffolds, the tensile strength, and elastic modulus remarkably increased up to 374% and 775%, respectively. The degradation of the reinforced PCL was 20 times higher than that of the non-reinforced PCL samples, after ten weeks, dominated by the fiber degradation phenomenon. After three days of cell culture, the proliferation assay of the built scaffovd the non-toxicity of the reinforced PCL.