Monomer Reactivity and Steric Factors affecting the Synthesis of Aromatic Polyamides

Muñoz, Dulce M.; Lozano, Ángel E.; Campa, José G. de la; Abajo, Javier de

doi:10.1177/0954008307081201

Cited by 9 publications

(7 citation statements)

References 25 publications

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“…The polyimides 6FDA–6FpDA and 6FDA–TMPD were synthesized from dianhydride 6FDA and two diamines, 6FpDA and TMPD, using an in situ silylation activated polyimidization method, according to the procedure reported elsewhere. − …”

Section: Experimental Sectionmentioning

confidence: 99%

New Materials for Gas Separation Applications: Mixed Matrix Membranes Made from Linear Polyimides and Porous Polymer Networks Having Lactam Groups

Aguilar‐Lugo

Suárez-Garcı́a

Hernández

et al. 2019

Ind. Eng. Chem. Res.

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A set of mixed matrix membranes (MMMs) has been prepared by incorporating a triptycene-isatin porous polymer network (PPN) to three aromatic polyimides (one commercial, Matrimid, and two synthesized by us: 6FDA–6FpDA and 6FDA–TMPD) covering a wide range of performances for gas separation. The triptycene-isatin PPN is a highly microporous network having a high CO2 uptake and high chemical and thermal stability. The good compatibility between the components (PPN content of 15 and 30% w/w) was supported by the increase in the glass transition temperature of MMMs relative to the pure polyimide membranes. The addition of the PPN particles improved the permeability of all the gases tested, by increasing diffusivity and, in some cases, gas solubility. The improvements were particularly noticeable in Matrimid-based MMMs, where gas permeability increased by 700%, whereas CO2/N2 and CO2/CH4 ideal selectivities decreased by a mere 4% and 12%, respectively.

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Section: Experimental Sectionmentioning

confidence: 99%

New Materials for Gas Separation Applications: Mixed Matrix Membranes Made from Linear Polyimides and Porous Polymer Networks Having Lactam Groups

Aguilar‐Lugo

Suárez-Garcı́a

Hernández

et al. 2019

Ind. Eng. Chem. Res.

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“…11,12 In previous papers, 13,14 we reported the synthesis of aromatic polyamides and polyimides by in situ silylation of diamines, and it was studied the role of a tertiary base such as pyridine as an activating agent when added to the silylated diamines. 15,16 This recently explored activation method has proven to be very efficient, yielding high molecular weight polymers even for diamines with steric hindrance. However, only medium-low molecular weight polymers were obtained from diamines with electron-withdrawing groups.…”

mentioning

confidence: 99%

An Improved Method for Preparing Very High Molecular Weight Polyimides

Muñoz¹,

Calle²,

Campa³

et al. 2009

Macromolecules

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Silylated diamines, as more nucleophilic reactants than diamines, were first reported as very suitable monomers for the synthesis of aromatic polyamides by Oishi et al. 1,2 Shortly after, polyimides from dianhydrides and silylated diamines were reported by the same authors. 3,4 Since then, the "silylation method" has successfully been extended to a variety of polyimides and to the preparation of other condensation polymers, such as poly(ether sulfone)s, 5 poly(ether ketone)s, 6 polyesters, 7 or polysulfides. 8 The initial disadvantages of this method, regarding water sensitivity and rigorous control of the reaction conditions, can be overcome with the use of in situ silylated diamines. This is performed by adding trimethylchlorosilane (TMSCl) or other silylating agents to the diamine solutions before adding the electrophilic monomer. The in situ silylation of the diamines presents some advantages; i.e., the TMSCl ensures that small amounts of water do not destroy the moisture-sensitive dianhydrides and, moreover, the experimental procedure is much easier as handling of silylated diamines is avoided.Not many examples have been reported in the literature, apart from silylation, regarding the in situ activation of amino groups. Although there are references dealing with the use of condensing agents 9 or the use of silylated monomers plus a catalyst, for example (NH 4 ) 2 SO 4 , acids, etc., 10 in the synthesis of wholly aromatic polymers, very few examples refer to the role of an organic base as an activating agent. 11,12 In previous papers, 13,14 we reported the synthesis of aromatic polyamides and polyimides by in situ silylation of diamines, and it was studied the role of a tertiary base such as pyridine as an activating agent when added to the silylated diamines. 15,16 This recently explored activation method has proven to be very efficient, yielding high molecular weight polymers even for diamines with steric hindrance. However, only medium-low molecular weight polymers were obtained from diamines with electron-withdrawing groups. Thus, polyimides with inherent viscosity of only 0.4 dL/g could be obtained when 4,4 0 -diaminodiphenyl sulfone (DDSO) was used.These results prompted us to investigate the effect of several activation agents in order to find out a general method to achieve high molecular weights irrespective of the electronic features of the aromatic diamines. Thus, several bases, with pK a ranging from 5.14 to 11.9, such as pyridine, N,N-dimethylaminopyridine (DMAP), triethylamine (Et 3 N), 1,3-diazabicyclo[5.4.0]undecane (DBU), and isoquinoline (IQ) were investigated as individual activating agents or as a pair (base/cobase) in the synthesis of polyimides. Moreover, other reaction conditions (base/cobase relative amount, reaction temperature, solvent, etc.) were also explored and here included.The results reported herein were obtained from a complete investigation of the best reaction conditions in the synthesis of polyimides from unreactive diamines: 6FDA-DDSO and 6FDA-6FpDA (Scheme 1). The latter...

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“…The aromatic polyimides, 6F6F and 6FTMPD, were prepared by a two-step polycondensation reaction of equimolecular amounts of 6FDA dianhydride and 6FpDA or TMPD diamine, by employing a base-assisted in-situ silylation method [32,[41][42][43]. The general procedure was the following: in a 100 mL three-necked flask, equipped with a mechanical stirrer and under nitrogen atmosphere, 9.0 mmol of diamine (6FpDA or TMPD) was dissolved in 9.0 mL of anhydrous DMAc.…”

Section: Synthesis Of Polyimidesmentioning

confidence: 99%

Mixed Matrix Membranes Loaded with a Porous Organic Polymer Having Bipyridine Moieties

et al. 2022

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Mixed matrix membranes (MMMs), derived from three aromatic polyimides (PIs), and an affordable porous organic polymer (POP) having basic bipyridine moieties were prepared. Matrimid and two fluorinated polyimides, which were derived from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride and 2,2′-bis(4-aminophenyl)hexafluoropropane (6F6F) or 2,4,6-trimethyl-m-phenylenediamine (6FTMPD), were employed as polymer matrixes. The used POP was a highly microporous material (surface area of 805 m2 g−1) with excellent thermal and chemical stability. The MMMs showed good compatibility between the PIs and POP, high thermal stabilities and glass transition temperatures superior to those of the neat PI membranes, and good mechanical properties. The addition of POP to the matrix led to an increase in the gas diffusivity and, thus, in permeability, which was associated with an increase in the fractional free volume of MMMs. The increase in permeability was higher for the less permeable matrix. For example, at 30 wt.% of POP, the permeability to CO2 and CH4 of the MMMs increased by 4- and 7-fold for Matrimid and 3- and 4-fold for 6FTMPD. The highest CH4 permeability led to a decrease in CO2/CH4 selectivity. The CO2/N2 separation performance was interesting, as the selectivity remained practically constant. Finally, the POP showed no molecular sieving effect towards the C2H4/C2H6 and C3H6/C3H8 gas pairs, but the permeability increased by about 4-fold and the selectivity was close to that of the matrix. In addition, because the POP can form metal ion bipyridine complexes, modified POP-based MMMs could be employed for olefin/paraffin separations.

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Monomer Reactivity and Steric Factors affecting the Synthesis of Aromatic Polyamides

Cited by 9 publications

References 25 publications

New Materials for Gas Separation Applications: Mixed Matrix Membranes Made from Linear Polyimides and Porous Polymer Networks Having Lactam Groups

New Materials for Gas Separation Applications: Mixed Matrix Membranes Made from Linear Polyimides and Porous Polymer Networks Having Lactam Groups

An Improved Method for Preparing Very High Molecular Weight Polyimides

Mixed Matrix Membranes Loaded with a Porous Organic Polymer Having Bipyridine Moieties

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