Ramiro Guerrero Santos | Centro de Investigación de Química Aplicada (CIQA) (original) (raw)
Uploads
Papers by Ramiro Guerrero Santos
European Polymer Journal, 1992
MISHRA and MATHTR: Radical polymerization of styrene initiated by dimethylsulfonium-m-nitrophenac... more MISHRA and MATHTR: Radical polymerization of styrene initiated by dimethylsulfonium-m-nitrophenacylide clearly reflected b y t h e high-pressure morphology due t o t h e controlled segregation of t h e different c-sequence lengths. Acta Polymerica 40 (1989) Nr. 7 483 Acknowledgements T h e author gratefully acknowledges the generous provision of research facilities i n t h e Institute of Solid S t a t e Physics a n d Electron Microscopy of t h e Academy of Sciences of t h e GDR i n Halle (Saale). Thanks are also due t o Dr. R. KUPFER for performing t h e high-pressure crystallization experiments a n d t o Dr. R. RAMLAU for his cooperation in electron microscopic work.
Journal of Applied Polymer Science, 1996
... DOI: 10.1002/(SICI)1097-4628(19960808)61:6<1055::AID-APP20&amp... more ... DOI: 10.1002/(SICI)1097-4628(19960808)61:6<1055::AID-APP20>3.0.CO;2-U. Copyright © 1996John Wiley & Sons, Inc. Issue. ... Enrique Reyna Hermosillo, 140, Apdo. ... Correspondence: Ramiro Guerrero Santos, Centro de Investigación en Química Aplicada, Blvd. ...
Polymer Chemistry
The use of thermo-responsive polymers in switchable catalysts enables the efficient and homogeneo... more The use of thermo-responsive polymers in switchable catalysts enables the efficient and homogeneous chemical recycling of post-consumer poly(ethylene terephthalate) and the heterogeneous separation of catalyst in a single system.
American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 2002
The present invention relates to a method for preparing a first generation polymer comprising a r... more The present invention relates to a method for preparing a first generation polymer comprising a radical polymerization step a composition comprising: - at least one ethylenically unsaturated monomer, - a source of free radicals, and- at least one organic compound ring having at least one group tetrathiophosphate.
Computer Aided Chemical Engineering, 2003
... and Sensitivity Analysis of a Living Free-Radical Polymerization Reactor Antonio Flores-Tlacu... more ... and Sensitivity Analysis of a Living Free-Radical Polymerization Reactor Antonio Flores-Tlacuahuac^, Enrique Saldivar-Guerra, Ramiro Guerrero-Santos ^Departamento de ... Dotson, R.Galvan, R.Laurence and M.Tirrell, Polymerization Reactor Model-ing, John Wiley, 1996 ...
Saldívar-Guerra/Handbook of Polymer Synthesis, Characterization, and Processing, 2013
ABSTRACT This chapter deals with the description of the free radical polymerization (FRP) mechani... more ABSTRACT This chapter deals with the description of the free radical polymerization (FRP) mechanism including initiation, propagation, and bimolecular termination reaction steps. Additional reactions such as chain transfer are introduced to improve the process description. In FRP, the progress of the reaction is measured in terms of conversion of monomer into polymer. The random character of the events defining the length of each polymeric chain leads to a distribution of molecular weights (MWs) instead of a unique MW as in the case of small molecules. The full molecular weight distribution (MWD) can be obtained either by probabilistic arguments or by a kinetic approach. The chapter then discusses thermodynamics of polymerization, and controlled radical polymerization (CRP). The most popular and successful techniques for performing CRP are stable free radical (SFR) or nitroxide-mediated radical polymerization (NMRP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation transfer (RAFT) polymerization.
Macromolecular Materials and Engineering, 2008
Novel materials were prepared from dual photo and thermal polymerization of hybrid thiolene/catio... more Novel materials were prepared from dual photo and thermal polymerization of hybrid thiolene/cationic systems. In the first stage, the thiol-ene system proceeded to high conversions, while the cationic photopolymerization was inhibited. The formation of sulfides during this stage was the main factor for the inhibition of the cationic photopolymerization of the epoxy monomers. Once those sulfides were formed, they reacted with the oxonium-terminated growing polyether chains to form trialkylsulfonium salts. These salts promoted the thermal polymerization of the epoxy monomers in the second stage. The viscoelastic properties of the resulting polymers were measured by DMA.
Macromolecular Engineering, 2022
Plants, 2021
Candidatus Liberibacter solanacearum (CaLso) is associated with diseases in tomato crops and tran... more Candidatus Liberibacter solanacearum (CaLso) is associated with diseases in tomato crops and transmitted by the tomato psyllid Bactericera cockerelli. A polymeric water-dispersible nanobactericide (PNB) was evaluated against CaLso as a different alternative. PNB is a well-defined polycationic diblock copolymer designed to permeate into the vascular system of plants. Its assessment under greenhouse conditions was carried out with tomato plants previously infected with CaLso. Using a concentration as low as 1.0 mg L−1, a small but significant reduction in the bacterial load was observed by real-time qPCR. Thus, to achieve an ecologically friendly dosage and set an optimum treatment protocol, we performed experiments to determine the effective concentration of PNB to reduce ~65% of the initial bacterial load. In a first bioassay, a 40- or 70-fold increase was used to reach that objective. At this concentration level, other bioassays were explored to determine the effect as a function o...
European Polymer Journal, 2021
Abstract After synthesis, specialty polymers can be difficult to purify from residual volatile mo... more Abstract After synthesis, specialty polymers can be difficult to purify from residual volatile monomers and solvents in a precise and reproducible manner using current standard separation techniques, which also generate large amounts of waste. Herein, we report a proof-of-principle study of a cost-effective and versatile method for separating residual volatile compounds from synthetic polymers via physisorption (i.e., polymer purification by physisorption (3P)). Model polymers were used to evaluate the capabilities and advantages of the 3P method over standard purification techniques regarding separation of volatile compounds, process solvent to polymer yield, and final properties of the resulting polymers. Compared to dialysis and precipitation, the 3P method could separate up to 99% of the residual monomer from a polymerization reaction using a significantly lower fraction of solvent. Unlike the benchmark methods, the molar mass and dispersity of polymers purified by the 3P process remain practically unaffected; polymers were quantitatively recovered for subsequent applications (e.g., precursors for block copolymer synthesis or characterization purposes). The 3P method represents a straightforward technique for polymer purification and is suitable for automation, which will help to overcome the unsolved and labor-intensive task of purifying (co-)polymer libraries derived from high-throughput experimentation.
Processes, 2019
A kinetic model for the dithiolactone-mediated radical polymerization of vinyl monomers based on ... more A kinetic model for the dithiolactone-mediated radical polymerization of vinyl monomers based on the persistent radical effect and reversible addition (negligible fragmentation) was used to calculate the polymerization rate and describe molar mass development in the polymerization of methyl methacrylate at 60 °C, using 2,2-azobisisobutyronitrile (AIBN) as an initiator, as well as dihydro-5-phenyl-2(3H)-thiophenethione (DTL1) and dihydro-2(3H)-thiophenethione (DTL2) as controllers. The model was implemented in the PREDICI commercial software. A good agreement between experimental data and model predictions was obtained.
Polymer Engineering & Science, 2019
In this contribution, the use of glycidyl methacrylate and styrene copolymers synthesized by nitr... more In this contribution, the use of glycidyl methacrylate and styrene copolymers synthesized by nitroxide-mediated polymerization (NMP) as chain extenders of postconsumer poly(ethylene terephthalate) waste (r-PET) is described. Our observations revealed that the copolymers synthesized by NMP act as efficient chain extenders for the regeneration of PET waste. Epoxide groups in the copolymers react with PET end reactive groups producing chain extended PET with higher molecular weight and improving performance. The increase in molecular weight of PET waste results in important improvement in both, elongation-at-break, and strength impact. r-PET complex viscosity and rheological moduli are also greatly improved as the epoxide content in the chain extenders increases. The loss tangent and phase angle versus angular frequency plots for chain-extended r-PET reveal that melt elasticity is also improved. These results confirm that use of NMP-synthesized copolymers is a plausible solution for the recycling of PET. POLYM. ENG.
![Research paper thumbnail of Effect of the Degree of Quaternization and Molar Mass on the Cloud Point of Poly[2-(dimethylamino)ethyl methacrylate] Aqueous Solutions: A Systematic Investigation](https://attachments.academia-assets.com/90105157/thumbnails/1.jpg)
](Macromolecular Chemistry and Physics, 2017
Macromolecular Chemistry and Physics, 2017
Polymers
The aim of this contribution is to assess the use poly(styrene-co-glycidyl methacrylate-b-styrene... more The aim of this contribution is to assess the use poly(styrene-co-glycidyl methacrylate-b-styrene) copolymers synthesized by nitroxide mediated polymerization (NMP) as chain extenders in the recycling of poly(lactic acid) biopolyester. Concisely, the addition of such block copolymers during the melt processing of recycled poly(lactic acid) (rPLA) leads to important increases in the viscosity average molecular weight of modified polymeric materials. Molar masses increase from 31,000 g/mol for rPLA to 48,000 g mol−1 for the resulting rPLA/copolymer blends (bPLA). Fortuitously, this last value is nearly the same as the one for pristine PLA, which constitutes a first piece of evidence of the molar mass increase of the recycled biopolymer. Thermograms of chain extended rPLA show significant decreases in cold crystallization temperature and higher crystallinity degrees due to the chain extension process using NMP-synthesized copolymers. It was found that increasing epoxide content in the ...
European Polymer Journal, 1992
MISHRA and MATHTR: Radical polymerization of styrene initiated by dimethylsulfonium-m-nitrophenac... more MISHRA and MATHTR: Radical polymerization of styrene initiated by dimethylsulfonium-m-nitrophenacylide clearly reflected b y t h e high-pressure morphology due t o t h e controlled segregation of t h e different c-sequence lengths. Acta Polymerica 40 (1989) Nr. 7 483 Acknowledgements T h e author gratefully acknowledges the generous provision of research facilities i n t h e Institute of Solid S t a t e Physics a n d Electron Microscopy of t h e Academy of Sciences of t h e GDR i n Halle (Saale). Thanks are also due t o Dr. R. KUPFER for performing t h e high-pressure crystallization experiments a n d t o Dr. R. RAMLAU for his cooperation in electron microscopic work.
Journal of Applied Polymer Science, 1996
... DOI: 10.1002/(SICI)1097-4628(19960808)61:6<1055::AID-APP20&amp... more ... DOI: 10.1002/(SICI)1097-4628(19960808)61:6<1055::AID-APP20>3.0.CO;2-U. Copyright © 1996John Wiley & Sons, Inc. Issue. ... Enrique Reyna Hermosillo, 140, Apdo. ... Correspondence: Ramiro Guerrero Santos, Centro de Investigación en Química Aplicada, Blvd. ...
Polymer Chemistry
The use of thermo-responsive polymers in switchable catalysts enables the efficient and homogeneo... more The use of thermo-responsive polymers in switchable catalysts enables the efficient and homogeneous chemical recycling of post-consumer poly(ethylene terephthalate) and the heterogeneous separation of catalyst in a single system.
American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 2002
The present invention relates to a method for preparing a first generation polymer comprising a r... more The present invention relates to a method for preparing a first generation polymer comprising a radical polymerization step a composition comprising: - at least one ethylenically unsaturated monomer, - a source of free radicals, and- at least one organic compound ring having at least one group tetrathiophosphate.
Computer Aided Chemical Engineering, 2003
... and Sensitivity Analysis of a Living Free-Radical Polymerization Reactor Antonio Flores-Tlacu... more ... and Sensitivity Analysis of a Living Free-Radical Polymerization Reactor Antonio Flores-Tlacuahuac^, Enrique Saldivar-Guerra, Ramiro Guerrero-Santos ^Departamento de ... Dotson, R.Galvan, R.Laurence and M.Tirrell, Polymerization Reactor Model-ing, John Wiley, 1996 ...
Saldívar-Guerra/Handbook of Polymer Synthesis, Characterization, and Processing, 2013
ABSTRACT This chapter deals with the description of the free radical polymerization (FRP) mechani... more ABSTRACT This chapter deals with the description of the free radical polymerization (FRP) mechanism including initiation, propagation, and bimolecular termination reaction steps. Additional reactions such as chain transfer are introduced to improve the process description. In FRP, the progress of the reaction is measured in terms of conversion of monomer into polymer. The random character of the events defining the length of each polymeric chain leads to a distribution of molecular weights (MWs) instead of a unique MW as in the case of small molecules. The full molecular weight distribution (MWD) can be obtained either by probabilistic arguments or by a kinetic approach. The chapter then discusses thermodynamics of polymerization, and controlled radical polymerization (CRP). The most popular and successful techniques for performing CRP are stable free radical (SFR) or nitroxide-mediated radical polymerization (NMRP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation transfer (RAFT) polymerization.
Macromolecular Materials and Engineering, 2008
Novel materials were prepared from dual photo and thermal polymerization of hybrid thiolene/catio... more Novel materials were prepared from dual photo and thermal polymerization of hybrid thiolene/cationic systems. In the first stage, the thiol-ene system proceeded to high conversions, while the cationic photopolymerization was inhibited. The formation of sulfides during this stage was the main factor for the inhibition of the cationic photopolymerization of the epoxy monomers. Once those sulfides were formed, they reacted with the oxonium-terminated growing polyether chains to form trialkylsulfonium salts. These salts promoted the thermal polymerization of the epoxy monomers in the second stage. The viscoelastic properties of the resulting polymers were measured by DMA.
Macromolecular Engineering, 2022
Plants, 2021
Candidatus Liberibacter solanacearum (CaLso) is associated with diseases in tomato crops and tran... more Candidatus Liberibacter solanacearum (CaLso) is associated with diseases in tomato crops and transmitted by the tomato psyllid Bactericera cockerelli. A polymeric water-dispersible nanobactericide (PNB) was evaluated against CaLso as a different alternative. PNB is a well-defined polycationic diblock copolymer designed to permeate into the vascular system of plants. Its assessment under greenhouse conditions was carried out with tomato plants previously infected with CaLso. Using a concentration as low as 1.0 mg L−1, a small but significant reduction in the bacterial load was observed by real-time qPCR. Thus, to achieve an ecologically friendly dosage and set an optimum treatment protocol, we performed experiments to determine the effective concentration of PNB to reduce ~65% of the initial bacterial load. In a first bioassay, a 40- or 70-fold increase was used to reach that objective. At this concentration level, other bioassays were explored to determine the effect as a function o...
European Polymer Journal, 2021
Abstract After synthesis, specialty polymers can be difficult to purify from residual volatile mo... more Abstract After synthesis, specialty polymers can be difficult to purify from residual volatile monomers and solvents in a precise and reproducible manner using current standard separation techniques, which also generate large amounts of waste. Herein, we report a proof-of-principle study of a cost-effective and versatile method for separating residual volatile compounds from synthetic polymers via physisorption (i.e., polymer purification by physisorption (3P)). Model polymers were used to evaluate the capabilities and advantages of the 3P method over standard purification techniques regarding separation of volatile compounds, process solvent to polymer yield, and final properties of the resulting polymers. Compared to dialysis and precipitation, the 3P method could separate up to 99% of the residual monomer from a polymerization reaction using a significantly lower fraction of solvent. Unlike the benchmark methods, the molar mass and dispersity of polymers purified by the 3P process remain practically unaffected; polymers were quantitatively recovered for subsequent applications (e.g., precursors for block copolymer synthesis or characterization purposes). The 3P method represents a straightforward technique for polymer purification and is suitable for automation, which will help to overcome the unsolved and labor-intensive task of purifying (co-)polymer libraries derived from high-throughput experimentation.
Processes, 2019
A kinetic model for the dithiolactone-mediated radical polymerization of vinyl monomers based on ... more A kinetic model for the dithiolactone-mediated radical polymerization of vinyl monomers based on the persistent radical effect and reversible addition (negligible fragmentation) was used to calculate the polymerization rate and describe molar mass development in the polymerization of methyl methacrylate at 60 °C, using 2,2-azobisisobutyronitrile (AIBN) as an initiator, as well as dihydro-5-phenyl-2(3H)-thiophenethione (DTL1) and dihydro-2(3H)-thiophenethione (DTL2) as controllers. The model was implemented in the PREDICI commercial software. A good agreement between experimental data and model predictions was obtained.
Polymer Engineering & Science, 2019
In this contribution, the use of glycidyl methacrylate and styrene copolymers synthesized by nitr... more In this contribution, the use of glycidyl methacrylate and styrene copolymers synthesized by nitroxide-mediated polymerization (NMP) as chain extenders of postconsumer poly(ethylene terephthalate) waste (r-PET) is described. Our observations revealed that the copolymers synthesized by NMP act as efficient chain extenders for the regeneration of PET waste. Epoxide groups in the copolymers react with PET end reactive groups producing chain extended PET with higher molecular weight and improving performance. The increase in molecular weight of PET waste results in important improvement in both, elongation-at-break, and strength impact. r-PET complex viscosity and rheological moduli are also greatly improved as the epoxide content in the chain extenders increases. The loss tangent and phase angle versus angular frequency plots for chain-extended r-PET reveal that melt elasticity is also improved. These results confirm that use of NMP-synthesized copolymers is a plausible solution for the recycling of PET. POLYM. ENG.
Macromolecular Chemistry and Physics, 2017
Macromolecular Chemistry and Physics, 2017
Polymers
The aim of this contribution is to assess the use poly(styrene-co-glycidyl methacrylate-b-styrene... more The aim of this contribution is to assess the use poly(styrene-co-glycidyl methacrylate-b-styrene) copolymers synthesized by nitroxide mediated polymerization (NMP) as chain extenders in the recycling of poly(lactic acid) biopolyester. Concisely, the addition of such block copolymers during the melt processing of recycled poly(lactic acid) (rPLA) leads to important increases in the viscosity average molecular weight of modified polymeric materials. Molar masses increase from 31,000 g/mol for rPLA to 48,000 g mol−1 for the resulting rPLA/copolymer blends (bPLA). Fortuitously, this last value is nearly the same as the one for pristine PLA, which constitutes a first piece of evidence of the molar mass increase of the recycled biopolymer. Thermograms of chain extended rPLA show significant decreases in cold crystallization temperature and higher crystallinity degrees due to the chain extension process using NMP-synthesized copolymers. It was found that increasing epoxide content in the ...