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Kinetic studies on RAFT inverse-suspension smart hydrogels formation using a te...
Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário Rui; Hernándes-Ortiz, JúlioTemperature/pH stimuli-responsive hydrogel particles were synthesized using inverse-suspension polymerization in batch stirred reactor. Different water soluble comonomers were present in the initial mixture (namely N-isopropylacrylamide and acrylic acid) as well as crosslinkers with different functionalities (bi-, tri- and tetrafunctional) so that their effect on the network crosslinking density could be seen. ...
Modelling studies on RAFT copolymerisation of styrene/divinylbenzene in aqueous...
Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário Rui; Hernándes-Ortiz, JúlioExperimental and theoretical studies concerning the RAFT copolymerization of styrene (S) and commercial divinylbenzene (DVB) were performed in order to assess the use of controlled radical polymerization (CRP) for the production of nonconventional polymer networks. Aqueous suspension polymerizations were carried out at a 1 L scale in a stirred batch reactor and changes of a few operation parameters were tried i...
NMRP of styrene-divinylbenzene: predictions in the pre- and post-gelation perio...
Aguiar, Leandro; Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário Rui; Giudici, ReinaldoThree modeling approaches for the NMRP of slyrene-divinylbenzene were used for describing experiments performed at different initial conditions: a rigorous approach (model A) based on balance of species and method of characteristics in terms of generating functions and two simplified approaches based upon mass and moment balances, numerical fractionation and pseudo-kinetic method (models B and C). Balances of p...
Mathematical modeling of styrene/divinylbenzene copolymerization comprising dif...
Aguiar, Leandro; Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Giudici, Reinaldo; Costa, Mário RuiMathematical Modeling of Styrene/Divinylbenzene Copolymerization Comprising Diffusional Effects and Cyclization Kinetics
Inverse-suspension production of hydrogels : kinetic modeling and product cha...
Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário RuiHydrogels find important applications in drug and gene delivery, tissue engineering, bio-separations and different fields of biomedicine.1 End-use properties of such polymer networks are dependent on their structural topology which is affected by the production process used. Formation of non-ideal networks due to reduced reactivity of pendant double bonds and/or cyclization are some mechanisms hindering the pre...
Kinetics of gelation in pH/temperature-sensitive hydrogels synthesis
Pinto, Virgínia; Gonçalves, Miguel; Dias, Rolando; Costa, Mário RuiKinetics of gelation was experimentally and theoretically studied for different polymerization systems leading to the formation of pH/temperature-sensitive hydrogels. Acrylamide (AAm), N-isopropylacrylamide (NIPA), N,Ndimethylacrylamide (DMA), acrylic acid (AA), methacrylic acid (MAA) were used as main monomers, and N,N’- methylenebisacrylamide (MBAm) as crosslinker.
Reversible addition-fragmentation chain transfer copolymerization of styrene/di...
Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário RuiThe Reversible Addition-Fragmentation Chain Transfer (RAFT) copolymerization of styrene (S) and divinylbenzene (DVB) was performed at temperature range 110 to 150 °C in aqueous suspension, using AIBN as thermal initiator and 2-dodecylthiocarbonothioylthio-2-methylpropionic acid (DDMAT) as RAFT agent.
Computer simulation aided synthesis of sodium acrylate/acrylic acid superabsorb...
Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário RuiThe influence of the synthesis conditions on the end use properties of SAPs was experimentally observed. Initial proportion crosslinker/acrylic acid and degree of neutralization are examples of parameters with strong influence in the performance of these materials. The kinetic model developed is able to capture the main features of SAP production. Ongoing research should allow the prediction of elastic properti...
Synthesis and characterization of pH-sensitive acrylamide/acrylic acid hydrogels
Pinto, Virgínia; Gonçalves, Miguel; Dias, Rolando; Costa, Mário RuiDifferent samples of pH-sensitive hydrogel particles were produced using inverse-suspension, leading to the identification of the influence on their end-use properties of the degree of neutralization of AA monomer and the initial composition of the terpolymerization system which are therefore the key parameters of the synthesis. These studies were also used to develop a kinetic model improving the design of pro...
Prediction of the dynamics of gel formation in superabsorbent polymer synthesis
Gonçalves, Miguel; Pinto, Virgínia; Dias, Rolando; Costa, Mário RuiThis work reports experimental and theoretical studies concerning SAP production through the copolymerization of acrylic acid with N,N’-methylenebisacrylamide (bifunctional crosslinker) or trimethylolpropane triacrylate (trifunctional crosslinker).
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