Preparation and characterization of hybrid thiol‐ene/epoxy UV–thermal dual‐cured systems

Sangermano, Marco; Cerrone, Monica; Colucci, Giovanna; Roppolo, Ignazio; Ortiz, Ricardo Acosta

doi:10.1002/pi.2822

Cited by 53 publications

(41 citation statements)

References 11 publications

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“…The heat evolved in the thiol-ene photopolymerization was also attributed as the responsible of the overlapping with epoxide homopolymerization in case of using pentallylamine as -ene monomer [18]. However, the extent of epoxide homopolymerization was even larger and could be detected when the proportion of allylic compound was only 10%.…”

Section: Study Of the Photopolymerization And Thermal Processmentioning

confidence: 95%

“…It has been reported that polysulfides derived from thiol-ene polymerization present some limitations in their physical/mechanical properties, particularly those related to modulus and attainment of high glass transition temperature due to the flexible core of the commercially available thiol monomers [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…This curing system was well suited for self-gluing of micropatterned parts for microfluidics [24] and adhesive wafer bonding [25]. Sangermano et al [26] proposed the use of a pentaallylic triamine curing agent which can react with multifunctional thiols to produce polysulfides in situ, and at the same time has the ability to initiate the anionic polymerization of an epoxy resin. Combining the network structure derived from the epoxy curing process with a thiol-ene system an important toughening effect was achieved due to the presence of the flexible polysulfide moieties.…”

Section: Introductionmentioning

confidence: 99%

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Multifunctional allyl-terminated hyperbranched poly(ethyleneimine) as component of new thiol–ene/thiol–epoxy materials

Acebo

Fernández‐Francos

Ramis

et al. 2016

Reactive and Functional Polymers

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Tarragona, October 23 th 2015Dear Prof. Advincula:We send our revised manuscript entitled: Multifunctional allyl-terminated hyperbranched poly(ethylenimine) as component of new thiol-ene/thiol-epoxy materials, to be accepted for publication in Reactive and Functional Polymers.We have included practically all the suggestions and corrections made by the reviewers and some answers to their questions have been included in the answer to the reviewer comments file.Looking forward to hearing from you, I remain. We agree and we have performed changes in the paragraph orders.3) Can you know the reaction rate of each scheme in scheme 3? It is not possible to measure both reaction rates, but the first is predominant over the second. We have decided to remove the second mechanism of thiol-epoxy condensation in Scheme 3, since the first equation is much more favorable than the second one. This is because the ammonium salt is much more acidic than the thiol, and then the formation of the thioether alcohol should take place only by the first equation.4) Please discuss the basicity of imidazole and so on. This information of base is important in this study. If we look to the pKa of the ammonium and imidazolium cations we realize that amines are more basic than imidazole (pKa of alkyl ammonium is ~10, whereas pKa of imidazolium is ~7). However, the problem arises from the amount of PEIene in the formulation. When the proportion of PEIene is high it catalyzes the second step in which a base is needed and thiol-epoxy reaction takes place overlapped. On the contrary, when the proportion of PEIene is low, then the basicity of the reaction medium is not enough to reach a complete thiol-epoxy conversion and 1-methylimidazole should be added. 5) Can you get mobility of electron in photo induced polymerization?No, there is no electron mobility. As the radical is formed it reacts instantaneously accordingly to a "click" reaction.6) Can you get turn over number in Scheme 2.The number of cycles is the same than the number of reacting molecules. It is a polycondensation mechanism and not a polyaddition reaction. Thiol-ene is a "click" reaction that occurs in a quantitative way. 7)In scheme 3, left side is same. combine it and only right side should be different scheme. Detailed Response to ReviewersWe have suppressed the second mechanism as commented above.Reviewer #2: Authors synthesized an allyl terminated hyperbranched poly(ethyleneimine). The multifunctional macromonomer has been used as -ene component in thiol-ene/thiol-epoxy curing formulations.Authors need to address the followings to meet publication requirements:1. Please add captions for schemes and figures, respectively.We apologize, but we forgot to add the file with the figure and scheme captions to the manuscript 2. Formats of Table 1, Table 2 and Table 3 are not consistent with each other. Please correct them. It is true. They have been corrected.3. There is a lack of discussion on how authors' work in comparison to others. It is important for authors to address this. formula...

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Section: Study Of the Photopolymerization And Thermal Processmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multifunctional allyl-terminated hyperbranched poly(ethyleneimine) as component of new thiol–ene/thiol–epoxy materials

Acebo

Fernández‐Francos

Ramis

et al. 2016

Reactive and Functional Polymers

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“…However, it is acknowledged that the radicals formed during photolysis of the cationic photoinitiator [16] can also accelerate the thiol-ene condensation. The sulfide bonds formed are nucleophilic enough to react with the oxonium cations that propagate the epoxy homopolymerization (see Scheme 3), leading to the formation of stable alkylsulfonium salts, slowing down or even stopping epoxy homopolymerization [12,13,17,18]. Alkylsulfonium salts can act as latent thermal cationic initiators, resuming dark epoxy polymerization upon post-curing at a higher temperature, thus allowing the material to reach complete conversion [17].…”

Section: Introductionmentioning

confidence: 99%

“…Another application of thiol-ene reaction is in the design of UV-curable B-stage adhesives, in combination with the cationic photopolymerization of epoxides [12,13]. Upon irradiation, the thiol-ene condensation leads to the formation of sulfide bonds (see Scheme 1) and to the photolysis of the photoinitiator, leading to the formation of a superacid capable of initiating the epoxy homopolymerization reactions (see Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

Photocuring and thermal post-curing of a cycloaliphatic epoxide resin with a trithiol and a vinyl epoxy compound

Morancho

Fernández‐Francos

Ramis

et al. 2015

J Therm Anal Calorim

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In this work, the influence of trimethylolpropane tris-(3-mercaptopropionate) and a vinyl epoxy compound (4-vinyl-1-cyclohexene 1,2-epoxide) over the photocuring and subsequent thermal curing of an epoxy resin (CYRACURE UVR-6105) is studied. The photoinitiator used is CYRACURE UVI-6976. The techniques used in this study have been DSC (differential scanning calorimetry) and FTIR (Fourier transform infrared spectroscopy). In the isothermal photocuring, when the proportion of the modifiers are 5 % or greater, the photopolymerization of the epoxy resin is stopped by the thiol-ene reaction of both modifiers, due to the formation of alkyl sulfonium salts, decreasing the maximum degree of conversion of the process. After the photocuring process, the different systems studied have been post-cured thermally and the activation energy of this process has been determined using a differential isoconversional method. When the epoxy resin is neat or only it has been added 2.5 % of the modifiers, at the beginning of the post-curing the activation energy decreases, but when the proportion of the modifiers is 5 % or greater, the activation energy always increases.

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Photochemically Driven Polymeric Network Formation: Synthesis and Applications

2017

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Polymeric networks have been intensely investigated and a large number of applications have been found in areas ranging from biomedicine to materials science. Network fabrication via light-induced reactions is a particularly powerful tool, since light provides ready access to temporal and spatial control, opening an array of synthetic access routes for structuring the network geometry as well as functionality. Herein, the most recent light-induced modular reactions and their use in the formation of precision polymeric networks are collated. The synthetic strategies including photoinduced thiol-based reactions, Diels-Alder systems, and photogenerated reactive dipoles, as well as photodimerizations, are discussed in detail. Importantly, applications of the fabricated networks via the aforementioned reactions are highlighted with selected examples. Concomitantly, we provide future directions for the field, emphasizing the most critically required advances.

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Preparation and characterization of hybrid thiol‐ene/epoxy UV–thermal dual‐cured systems

Cited by 53 publications

References 11 publications

Multifunctional allyl-terminated hyperbranched poly(ethyleneimine) as component of new thiol–ene/thiol–epoxy materials

Multifunctional allyl-terminated hyperbranched poly(ethyleneimine) as component of new thiol–ene/thiol–epoxy materials

Photocuring and thermal post-curing of a cycloaliphatic epoxide resin with a trithiol and a vinyl epoxy compound

Photochemically Driven Polymeric Network Formation: Synthesis and Applications

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