Advances in cationic photopolymerization

2012 ◽  
Vol 84 (10) ◽  
pp. 2089-2101 ◽  
Author(s):  
Marco Sangermano
Keyword(s):  
Mechanical Properties ◽  
Uv Light ◽  
Uv Curing ◽  
Vinyl Ethers ◽  
Good Adhesion ◽  
High Interest ◽  
Onium Salts ◽  
Cationic Photopolymerization

This review discusses cationic UV-curing processes of vinyl ethers, propenyl ethers, and epoxy monomers. Cationic photopolymerization based on photogeneration of acid from onium salts induced by UV light and consecutive polymerization initiated by photogenerated acid was first proposed at the end of the 1970s. The process engendered high interest both in academia and in industry. Cationic photoinduction presents some advantages over comparable radical-mediated processes, particularly the absence of inhibition by oxygen, low shrinkage, and good adhesion, and mechanical properties of the UV-cured materials. Moreover, the monomers employed are generally less toxic and irritant than acrylates and methacrylates, which are widely used in radical photopolymerization. In this overview, particular emphasis is given to our recent contributions to the field of cationic photopolymerization for different classes of monomers.

scholarly journals Properties and role of interfaces in multimaterial 3D printed composites

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Laura Zorzetto ◽  
Luca Andena ◽  
Francesco Briatico-Vangosa ◽  
Lorenzo De Noni ◽  
Jean-Michel Thomassin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Uv Light ◽  
Finite Size ◽  
Uv Curing ◽  
Building Blocks ◽  
Layer By Layer ◽  
Bimaterial Interfaces ◽  
3D Printed ◽  
Architectured Materials ◽  
The Impact

AbstractIn polyjet printing photopolymer droplets are deposited on a build tray, leveled off by a roller and cured by UV light. This technique is attractive to fabricate heterogeneous architectures combining compliant and stiff constituents. Considering the layer-by-layer nature, interfaces between different photopolymers can be formed either before or after UV curing. We analyzed the properties of interfaces in 3D printed composites combining experiments with computer simulations. To investigate photopolymer blending, we characterized the mechanical properties of the so-called digital materials, obtained by mixing compliant and stiff voxels according to different volume fractions. We then used nanoindentation to measure the spatial variation in mechanical properties across bimaterial interfaces at the micrometer level. Finally, to characterize the impact of finite-size interfaces, we fabricated and tested composites having compliant and stiff layers alternating along different directions. We found that interfaces formed by deposition after curing were sharp whereas those formed before curing showed blending of the two materials over a length scale bigger than individual droplet size. We found structural and functional differences of the layered composites depending on the printing orientation and corresponding interface characteristics, which influenced deformation mechanisms. With the wide dissemination of 3D printing techniques, our results should be considered in the development of architectured materials with tailored interfaces between building blocks.

Mechanical Characterization of UV Photopolymerized PMMA with Different Photo-Initiator Concentration

2021 ◽  
Vol 903 ◽  
pp. 11-16
Author(s):  
M.A. Manjunath ◽  
K. Naveen ◽  
Prakash Vinod ◽  
N. Balashanmugam ◽  
M.R. Shankar
Keyword(s):  
Mechanical Properties ◽  
Light Source ◽  
Polymethyl Methacrylate ◽  
Biomedical Applications ◽  
Mechanical Characterization ◽  
Uv Light ◽  
Curing Time ◽  
Uv Led ◽  
Pmma Resin

Polymethyl methacrylate (PMMA) is one among few known photo-polymeric resin useful in lithography for fabricating structures having better mechanical properties to meet the requirement in electronics and biomedical applications. This study explores the effect of Photo Initiator (PI) concentration and also curing time on strength and hardness of Polymethyl methacrylate (PMMA) obtained by UV photopolymerization of Methyl methacrylate (MMA) monomer. The UV LED light source operating at the wavelength of 364 nm is used with Benzoin Ethyl Ether (BEE) as photo initiator. The curing of PMMA resin is supported with peltier cooling device placed at the bottom of the UV light source. The characterisation study of UV photo cured PMMA is analysed through nano indenter (Agilent Technologies-G200). The current work investigates the influence of PI concentration and curing time in achieving maximum mechanical properties for UV photopolymerized PMMA.

UV-Curable organic-inorganic hybrid films based on tetraethylorthosilicate oligomer and special acrylated polyester

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Jianyun He ◽  
Jinping Xiong ◽  
Bingqian Xia
Keyword(s):  
Uv Light ◽  
Uv Curing ◽  
Organic Matrix ◽  
Dynamic Mechanical Properties ◽  
Hybrid Films ◽  
Uv Curable ◽  
Inorganic Hybrid ◽  
Dynamic Mechanical ◽  
H Nmr ◽  
Uv Curing Process

AbstractOrganic-inorganic hybrid films were prepared using tetraethylorthosilicate (TEOS) oligomer and special acrylated polyester (SAP) via a UV-curing process. TEOS oligomers were prepared in the presence of water and ethanol using hydrochloric acid as the catalyst and characterized using 1H NMR, 29Si NMR and MALDI-TOF mass spectra. Special acrylated polyester was synthesized by 1,4-cyclohexane dimethanol, neopentyl glycol, 1,4-butanediol, maleic anhydride, adipic acid, and acrylic acid. Hybrid films were cured by UV light and the thermal properties, dynamic mechanical properties, and tensile properties of the hybrid films were evaluated as the function of TEOS oligomer content. The morphology of the hybrid films was examined using atomic force microscopy (AFM). The microscopy and dynamic mechanical data indicated that the hybrid films were heterogeneous materials with various inorganic particle sizes dispersed within the organic matrix. The results indicated that after incorporating the TEOS oligomer, the strength and thermal stability of the hybrid films were enhanced.

The effect of hydroxyspiro-orthocarbonates on the cationic photopolymerization of an epoxy resin and on the mechanical properties of the final polymer

2011 ◽  
Vol 61 (4) ◽  
pp. 587-595 ◽  
Author(s):  
Ricardo Acosta Ortiz ◽  
Amy Grace Savage Gomez ◽  
María Lydia Berlanga Duarte ◽  
Marco Sangermano
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Cationic Photopolymerization

Facile fabrication of photoinduced superhydrophobic–superhydrophilic surfaces on cellulose substrate without strength loss

2018 ◽  
Vol 89 (9) ◽  
pp. 1807-1822
Author(s):  
Yunjie Yin ◽  
Yanyan Zhang ◽  
Xiaoqian Ji ◽  
Tao Zhao ◽  
Chaoxia Wang
Keyword(s):  
Mechanical Properties ◽  
Uv Irradiation ◽  
Uv Curing ◽  
Contact Angles ◽  
Curing Process ◽  
Water Contact ◽  
Cellulose Substrate ◽  
Cellulose Substrates ◽  
Uv Curing Process ◽  
Modified Cellulose

A novel strategy was reported on the design and fabrication of functional photosensitive hybrid sols (FPHSs) by non-alcoholic emulsification in the presence of a TiO2 nanoparticle and photoinitiator via a sol-gel process using tetraethylorthosilicate, γ-methacryloxypropyltrimethoxysilane (MPS) and hydrophobic silane coupling agents as precursors. Smart cellulose substrates with alterable superhydrophobic–superhydrophilic conversion were fabricated using FPHS via the ultraviolet (UV) curing process. The liquid FPHS was photocured into solid gel during UV irradiation for 40 s with MPSs in FPHS, which was verified via Fourier transform infrared spectra. The cellulose substrates were modified with FPHSs, and the water contact angles of the modified cellulose substrates were more than 150°. The superhydrophobicity was improved by the gathering of hydrophobic chains and particle deposition of hybrid gel on the fiber surface. Nevertheless, the water contact angles of the modified cellulose substrates were receded with UV irradiation from 158° to 0° in 200 min, due to TiO2 photoinduction. The irradiated cellulose substrates were placed in the dark, and the water contact angles were recovered to about 130°, gradually. What is more, the reversible process can be repeated more than eight times. The modified cellulose substrate presented excellent washing fastness, even suffering 10 times washing processing. The mechanical properties, including breaking strength and elongation rate, were improved after the coating and UV curing process, which considerably remedied the defects of the heating curing process on the mechanical properties.

Preparation and antibacterial properties of an AgBr@SiO2/GelMA composite hydrogel

2022 ◽  
Author(s):  
Bo Li ◽  
Hong Li ◽  
Haocheng Yang ◽  
Yue Shu ◽  
Kejiang Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Uv Light ◽  
Antibacterial Properties ◽  
Silver Ions ◽  
Skin Wound ◽  
Wound Dressings ◽  
Sprague Dawley ◽  
Sio2 Microspheres ◽  
Modified Stöber Method

Abstract Pure gelatin hydrogels lack antibacterial function and have poor mechanical properties, which restrict their application in wound dressings. In this study, nanosized silver bromide-doped mesoporous silica (AgBr@SiO2) microspheres with hollow structures were prepared by a modified Stober method. The novel microspheres can not only release silver ions to treat bacteria but also release drugs to treat skin wound. Furthermore, AgBr@SiO2 microspheres were modified with propyl methacrylate, incorporated into methacrylated gelatin (GelMA), and crosslinked by UV light to prepare AgBr@SiO2/GelMA dressings consisting of composite hydrogels. The results showed that the AgBr@SiO2 microspheres could enhance the mechanical properties of the hydrogels. With the increase in the AgBr@SiO2 concentration from 0.5 to 1 mg/mL, the dressings demonstrated effective antimicrobial activity against both Staphylococcus aureus and Escherichia coli. Furthermore, full-thickness skin wounds in vivo wound healing studies with Sprague–Dawley rats were evaluated. When treated with AgBr@SiO2/GelMA containing 1 mg/mL AgBr@SiO2, only 15% of the wound area left on day 10. Histology results also showed the epidermal and dermal layers were better organized. These results suggest that AgBr@SiO2/GelMA-based dressing materials could be promising candidates for wound dressings.

scholarly journals Elaboration and Characterization of Active Apple Starch Films Incorporated with Ellagic Acid

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 384
Author(s):  
Juan Tirado-Gallegos ◽  
Paul Zamudio-Flores ◽  
José Ornelas-Paz ◽  
Claudio Rios-Velasco ◽  
Guadalupe Olivas Orozco ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Water Vapor ◽  
Antioxidant Capacity ◽  
Ellagic Acid ◽  
Uv Light ◽  
Water Vapor Permeability ◽  
Vapor Permeability ◽  
Starch Films

Apple starch films were obtained from apples harvested at 60, 70, 80 and 90 days after full bloom (DAFB). Mechanical properties and water vapor permeability (WVP) were evaluated. The apple starch films at 70 DAFB presented higher values in the variables of tensile strength (8.12 MPa), elastic modulus (3.10 MPa) and lower values of water vapor permeability (6.77 × 10−11 g m−1 s−1 Pa−1) than apple starch films from apples harvested at 60, 80 and 90 DAFB. Therefore, these films were chosen to continue the study incorporating ellagic acid (EA). The EA was added at three concentrations [0.02% (FILM-EA0.02%), 0.05% (FILM-EA0.05%) and 0.1% (FILM-EA0.1%) w/w] and compared with the apple starch films without EA (FILM-Control). The films were characterized by their physicochemical, optical, morphological and mechanical properties. Their thermal stability and antioxidant capacity were also evaluated. The FILM-Control and FILM-EA0.02% showed a uniform surface, while FILM-EA0.05% and FILM-EA0.1% showed a rough surface and insoluble EA particles. Compared to FILM-Control, EA modified the values of tensile strength, elasticity modulus and elongation at break. The antioxidant capacity increased as EA concentration did. EA incorporation allowed obtaining films with higher antioxidant capacity, capable of blocking UV light with better mechanical properties than film without EA.

scholarly journals UV Irradiated Graphene-Based Nanocomposites: Change in the Mechanical Properties by Local HarmoniX Atomic Force Microscopy Detection

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 962 ◽  
Author(s):  
Liberata Guadagno ◽  
Carlo Naddeo ◽  
Marialuigia Raimondo ◽  
Vito Speranza ◽  
Roberto Pantani ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Mechanical Stability ◽  
Uv Light ◽  
Ultra Violet ◽  
Graphene Nanoplatelets ◽  
Free Standing ◽  
Force Microscopy ◽  
Atomic Force ◽  
Acquisition Mode

Epoxy based coatings are susceptible to ultra violet (UV) damage and their durability can be significantly reduced in outdoor environments. This paper highlights a relevant property of graphene-based nanoparticles: Graphene Nanoplatelets (GNPs) incorporated in an epoxy-based free-standing film determine a strong decrease of the mechanical damages caused by UV irradiation. The effects of UV light on the morphology and mechanical properties of the solidified nanocharged epoxy films are investigated by Atomic Force Microscopy (AFM), in the acquisition mode “HarmoniX.” Nanometric-resolved maps of the mechanical properties of the multi-phase material evidence that the incorporation of low percentages, between 0.1% and 1.0% by weight, of graphene nanoplatelets (GNPs) in the polymeric film causes a relevant enhancement in the mechanical stability of the irradiated films. The beneficial effect progressively increases with increasing GNP percentage. The paper also highlights the potentiality of AFM microscopy, in the acquisition mode “HarmoniX” for studying multiphase polymeric systems.

Profiling of the Mechanical Properties of Ultralow-k Films Using Nanoindentation Techniques

2011 ◽  
Vol 1297 ◽  
Author(s):  
Holm Geisler ◽  
Ulrich Mayer ◽  
Matthias U. Lehr ◽  
Petra Hofmann ◽  
Hans-Juergen Engelmann
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Light Absorption ◽  
Uv Light ◽  
Lower Surface ◽  
Rear Side ◽  
Plastic Properties ◽  
Dynamic Mechanical ◽  
Reduced Modulus ◽  
Good Agreement

ABSTRACTSeveral nanoindentation techniques were applied to the surface, the reverse side and cross-sections of PECVD ultralow-k (ULK) film stacks to characterize their elasto-plastic properties quantitatively. Results showed good agreement of the reduced modulus (Er) values measured from above and on cross-sections, respectively. Er decreased by 10-22% from the upper to the lower surface of the films. This gradient suggests that UV light absorption inside the film leads to slightly reduced curing at the rear side of the films compared to the surface of the ULK layers. Both quasi-static nanoindentation and dynamic mechanical mapping showed this trend. It is demonstrated that quantitative mechanical mapping can be performed with a lateral resolution ≤ 100nm. Slight local variations of Er were detected on ULK/SiCxNy films stacked on top of Cu-low-k interconnect structures.

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