| 1. |
- Claudino, Mauro, et al.
(author)
-
Bringing D-limonene to the scene of bio-based thermoset coatings via free-radical thiol-ene chemistry : macromonomer synthesis, UV-curing and thermo-mechanical characterization
- 2014
-
In: Polymer Chemistry. - : Royal Society of Chemistry (RSC). - 1759-9954. ; 5:9, s. 3245-3260
-
Journal article (peer-reviewed)abstract
- The increasing pursuit for bio-based plastic materials led us to investigate the potential use of the monoterpene limonene in thermoset synthesis using the free-radical mediated thiol-ene reaction. The high efficiency of this reaction to prepare multifunctional ene-terminated resins, as intermediary macromolecular precursors, for thermosets synthesis was demonstrated under thermal and photoinitiated conditions. Although an excess of terpene favors formation of well-defined macromonomers in organic solution, the characteristic low-vapor pressure of limonene hinders its simple removal (or recycling) via evaporation after synthesis. Alteration to an initial thiol-ene stoichiometry of 1 : 0.5 enables production of high molecular weight resins in the form of 'hyperbranched oligomeric-like' structures having moderate polydispersity. UV-curing of these polyfunctional resins combined with equal mole compositions of multifunctional alkyl ester 3-mercapto propionates yields highly sticky, amorphous and flexible elastomers with different thermo-mechanical properties. These can be further modulated by varying the amount of unreacted thiol occluded within the networks working as a plasticizer. Introduction of a renewable cycloaliphatic structure into the materials offers a convenient way to enhance the glass-transition temperature and stiffness of traditional thiol-ene networks. The materials synthesized may be considered potentially useful as sealants and adhesives in a wide variety of applications including organic coatings. The versatility of UV-irradiation over thermal initiation makes this method particularly suitable for green industrial synthesis processes via thiol-ene chemistry using limonene and multifunctional thiols. The thiol-ene system evaluated herein serves as a model example for the sustainable incorporation of natural diolefinic monomers into semisynthetic thiol-ene networks exhibiting a range of thermo-mechanical properties.
|
|
| 2. |
- Claudino, Mauro, et al.
(author)
-
Photoinduced thiol-ene cross-linking of globalide/ε-caprolactone copolymers : curing performance and resulting thermoset properties
- 2012
-
In: Journal of Polymer Science Part A. - : Wiley. - 0887-624X .- 1099-0518. ; 50:1, s. 16-24
-
Journal article (peer-reviewed)abstract
- The increasing demand for bioderived polymers led us to investigate the potential use of the macrolactone globalide in thermoset synthesis via the photoinduced thiolene reaction. A series of six lipase-catalyzed poly(globalide-caprolactone) copolyesters bearing internal main-chain unsaturations ranging from 10 to 50 and 100 mol % were successfully crosslinked in the melt with equal amounts of thiol groups from trimethylolpropane-trimercapto propionate affording fully transparent amorphous elastomeric materials with different thermal and viscoelastic properties. Three major conclusions can be drawn from this study: (i) high thiol-ene conversions (> 80%) were easily attained for all cases, while maintaining the cure behavior, and irrespective of functionality at reasonable reaction rates; (ii) parallel chain-growth homopropagation of the ene monomer is insignificant when compared with the main thiolene coupling route; and (iii) high ene-density copolymers result in much lower extracted sol fractions and high T(g) values as a result of a more dense and homogeneous crosslinked network. The thiol-ene system evaluated in this contribution serve as model example for the sustainable use of naturally occurring 1,2-disubstituted alkenes in making semisynthetic polymeric materials in high conversions with a range of properties.
|
|
| 3. |
- Claudino, Mauro, et al.
(author)
-
Thiol-ene coupling of 1,2-disubstituted alkene monomers : The kinetic effect of cis/trans-isomer structures
- 2010
-
In: European Polymer Journal. - : Elsevier BV. - 0014-3057 .- 1873-1945. ; 46:12, s. 2321-2332
-
Journal article (peer-reviewed)abstract
- The free-radical induced reaction between a tri-functional thiol (2-ethyl-(hydroxymethyl)-1,3-propanediol trimercapto propionate) and two 1,2-disubstituted alkenes (methyl oleate and methyl elaidate) has been investigated under photochemical conditions. The photoreaction was monitored via time-resolved FUR, Raman and NMR spectroscopy to provide insights about the kinetics and efficiency in end-product formation. The information collected was subjected to numerical modelling using the GEPASI software using pre-established literature values for the rate coefficients in order to verify the proposed reaction scheme. The results confirm the thiol-ene reaction mechanism showing a very fast cis/trans-isomerization (<1.0 min) when compared with the total disappearance of unsaturations, indicating that the rate-limiting step controlling the reaction is the hydrogen transfer from the thiol involved in the formation of product. High thiol-ene conversions can be obtained at reasonable rates without major influence of side-reactions when performed in bulk indicating that this reaction is suitable for network forming purposes with mono-unsaturated fatty acid methyl esters derivatives. The kinetic and mechanistic information collected provides a basis for the design of new thiol-ene systems aiming at material and coating applications.
|
|
| 4. |
- Claudino, Mauro
(author)
-
Thiol−ene Coupling of Renewable Monomers : at the forefront of bio-based polymeric materials
- 2011
-
Licentiate thesis (other academic/artistic)abstract
- Plant derived oils bear intrinsic double-bond functionality that can be utilized directly for the thiol–ene reaction. Although terminal unsaturations are far more reactive than internal ones, studies on the reversible addition of thiyl radicals to 1,2-disubstituted alkenes show that this is an important reaction. To investigate the thiol–ene coupling reaction involving these enes, stoichiometric mixtures of a trifunctional propionate thiol with monounsaturated fatty acid methyl esters (methyl oleate or methyl elaidate) supplemented with 2.0 wt.% Irgacure 184 were subjected to 365-nm UV-irradiation and the chemical changes monitored. Continuous (RT– FTIR) and discontinuous (NMR and FT–Raman) techniques were used to follow the progress of the reaction and reveal details of the products formed. Experimental results supported by numerical kinetic simulations of the system confirm the reaction mechanism showing a very fast cis/trans-isomerization of the alkene monomers (<1.0 min) when compared to the total disappearance of double-bonds, indicating that the rate-limiting step controlling the overall reaction is the hydrogen transfer from the thiol involved in the formation of final product. The loss of total unsaturations equals thiol consumption throughout the entire reaction; although product formation is strongly favoured directly from the trans-ene. This indicates that initial cis/trans-isomer structures affect the kinetics. High thiol–ene conversions could be easily obtained at reasonable rates without major influence of side-reactions demonstrating the suitability of this reaction for network forming purposes from 1,2-disubstituted alkenes. To further illustrate the validity of this concept in the formation of cross-linked thiol–ene films a series of globalide/caprolactone based copolyesters differing in degree of unsaturations along the backbone were photopolymerized in the melt with the same trithiol giving amorphous elastomeric materials with different thermal and viscoelastic properties. High thiol–ene conversions (>80%) were easily attained for all cases at reasonable reaction rates, while maintaining the cure behaviour and independent of functionality. Parallel chain-growth ene homopolymerization was considered negligible when compared with the main coupling route. However, the comonomer feed ratio had impact on the thermoset properties with high ene-density copolymers giving networks with higher glass transition temperature values (Tg) and a narrower distribution of cross-links than films with lower ene composition. The thiol–ene systems evaluated in this study serve as model example for the sustainable use of naturally-occurring 1,2-disubstituted alkenes at making semi-synthetic polymeric materials in high conversions with a range of properties in an environment-friendly way.
|
|
| 5. |
- Finnveden, Maja, et al.
(author)
-
One-Component Thiol-Alkene Functional Oligoester Resins Utilizing Lipase Catalysis
- 2016
-
In: Macromolecular Chemistry and Physics. - : John Wiley & Sons. - 1022-1352 .- 1521-3935.
-
Journal article (peer-reviewed)abstract
- Chemo-enzymatic methods are powerful tools for the synthesis of novel materials. By combining the flexibility of chemical synthesis and the high selectivity of enzymes, a variety of functional materials can be achieved. In the present study, a series of α,ω-thiol telechelic oligoesters with varying amount of internal alkenes are prepared using selective lipase catalysis and are subsequently cross-linked by thiol-ene chemistry yielding alkene functional networks. Due to the reactivity of thiols and alkenes almost all present thiol-ene systems consist of two components. This work demonstrates that selective lipase catalysis in combination with renewable monomers with internal alkenes is a promising system for achieving one-component thiol-alkene functional resins with good storage stability and a high degree of thiol end-groups. The developed chemo-enzymatic route yields polymer networks with tailored amount of alkene functionalities in the final thermoset, which facilitate further postmodification.
|
|
| 6. |
- Johansson, Katarina, et al.
(author)
-
A Model Study on Fatty Acid Methyl Esters as Reactive Diluents in Thermally Cured Coil Coating Systems
- 2006
-
In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 55:4, s. 382-387
-
Journal article (peer-reviewed)abstract
- A model study on the transesterification reaction between fatty acid methyl ester (FAME), e.g. methyl oleate, methyl linoleate, rape seed methyl ester and different alcohols in thin films have been performed. The purpose was to evaluate the possibility to use fatty acid methyl ester (FAME) as reactive diluent in thermally cured coil-coating paints. A reactive diluent must be compatible, act as a diluent, react into the film without affecting the end properties. The transesterification between the methyl ester and hydroxyl functional model compounds was monitored by 1H-NMR and real time IR. The effects addressed in the present study were compatibility, temperature, catalyst, alcohol structure, and fatty acid methyl ester (FAME) structure. Competing factors with the transesterification reaction were shown to be evaporation and side reactions i.e. oxidation. The structure of the fatty acid methyl ester (FAME) affects the conversion as a higher amount of unsaturations triggers the competing side reaction oxidation. The reaction time and temperature affects both the degree of transesterification conversion, degree of side reactions and the catalyst choice. The present study has shown that a fatty acid methyl ester (FAME) fulfils the reactivity part for a reactive diluent in a thermally cured coating system.
|
|
| 7. |
- Johansson, Katarina, et al.
(author)
-
Fatty Acid Methyl Ester as Reactive Diluent in Thermally Cured Solvent-Borne Coil-Coatings : The Effect of Fatty Acid Pattern on the Curing Performance and Final Properties
- 2008
-
In: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 63:2, s. 155-159
-
Journal article (peer-reviewed)abstract
- Four different fatty acid methyl esters (FAMEs): rape seedmethyl ester (RME), tall oil methyl ester (TOME), and two types of linseed oilmethyl ester (Linutin) have been studied as reactive diluents in thermally cured solvent-borne coil-coatings. The purpose was to evaluate the effect of fatty acid methyl ester structure on the curing performance and final properties of the coating. The permanent incorporation of the reactive diluent via transesterification reaction has been followed with 1H NMR analysis of model systems. Dynamic mechanical analysis (DMA) measurements, of free-standing films, showthat the glass transition temperature (Tg) decreases upon addition of the reactive diluent. Both the amount of incorporated reactive diluent and the final film properties are affected by the number and placement of alkene-bonds in the FAME.
|
|
| 8. |
|
|
| 9. |
- Johansson, Katarina, et al.
(author)
-
Hyperbranched Aliphatic Polyesters and Reactive Diluents in Thermally Cured Coil Coatings
- 2009
-
In: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 1:1, s. 211-217
-
Journal article (peer-reviewed)abstract
- Two hydroxy-functional hyperbranched aliphatic polyesters based on 2,2-dimethylolpropionic acid (bis-MPA) and a partially aromatic conventional polyester have been studied as thermoset resins for solvent-borne thermally cured polyester crosslinked with melamine coatings for precoated sheet metal, i.e., coil coatings. The hyperbranched polyesters differ with respect to the ratio of the end groups, being either hydroxyls or alkyl esters. The rheological properties of formulations with different polyester resin composition and reactive diluent, Le., rape seed methyl ester, content have been evaluated with viscosity measurements. Films cured either under industrial cure conditions to obtain a peak metal temperature of 232-241 degrees C or at a lower temperature, i.e., 130 degrees C, on untreated or organic primer-coated hot-dipped-galvanized steel substrates have been prepared. The film properties have been evaluated with differential scanning calorimetry and conventional film characterization techniques, i.e., adhesion, impact, Erichsen cupping, pencil hardness, microhardness, and scratch and chemical resistance tests. Formulations possessing high drying ability with maintained suitable film application viscosity were obtained using a hyperbranched polyester resin and a reactive diluent. It is proposed that a solvent-free polyester/melamine formulation with sufficient film properties to withstand the rough forming procedures associated with coil coatings can be obtained by further modification of the resin and greater amounts of reactive diluent.
|
|
| 10. |
- Johansson, Katarina, et al.
(author)
-
Hyperbranched Aliphatic Polyesters as Thermoset Resins for Thermally Cured Coil-Coatings
-
Other publication (other academic/artistic)abstract
- Two hydroxy-functional hyperbranched aliphatic polyesters based on 2,2-dimethylol propionic acid (bis-MPA) and a partially aromatic conventional polyester have been studied as thermoset resins for solvent-borne thermally cured polyester cross-linked with melamine coatings for pre-coated sheet metal, i.e. coil-coatings. The hyperbranched polyesters differ with respect to ratio of the end-groups being either hydroxyls or alkyl esters. The rheological properties of formulations with different polyester resin composition and reactive diluent, i.e. rape seed methyl ester (RME), content have been evaluated with viscosity measurements. Films cured either under industrial cure conditions to obtain a peak metal temperature (PMT) of 232-241°C or at a lower temperature, i.e. 130°C, on untreated or organic primer coated hot dipped galvanized (HDG) steel substrates have been prepared. The film properties have been evaluated with differential scanning calorimetry (DSC), and conventional film characterization techniques i.e. adhesion, impact, Erichsen cupping, pencil hardness, micro hardness, scratch and chemical resistance tests. Formulations possessing high drying ability with maintained suitable film application viscosity were obtained using a hyperbranched polyester resin and a reactive diluent. It is proposed that a solvent-free polyester/melamine formulation with sufficient film properties to withstand the rough forming procedures associated with coil-coatings can be obtained by further modification of the resin and greater amounts of reactive diluent.
|
|
