Towards a general understanding of hydrothermal polymerization of polyimides

Baumgartner, Bettina; Puchberger, Michael; Unterlass, Miriam M.

doi:10.1039/c5py00231a

Cited by 48 publications

(97 citation statements)

References 24 publications

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“…This is a major improvement, since the a ‐phase is the major product phase. Such a high degree of morphological ordering is to date unprecedented in hydrothermally polymerized aromatic PIs . At this point—irrespective of the detailed mode‐of‐action of PEG8000 during HTP—it seemed reasonable to aim for decreasing reaction and crystallization rates of PPPI and thereby check if the impact of PEG8000 could be even stronger.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, HTP is termed a geomimetic polycondensation . To date HTP has been exclusively reported for the preparation of polyimides (PIs), and PI/SiO 2 hybrid materials . In a typical HTP experiment, the comonomers toward PIs, i.e., a diamine and a dianhydride (typically employed as the corresponding tetracarboxylic acid) are mixed in H 2 O at RT ≤ T < 100 °C ( Figure A).…”

Section: Introductionmentioning

confidence: 99%

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Exerting Additive‐Assisted Morphological Control during Hydrothermal Polymerization

Taublaender

Reiter

Unterlass

2017

Macro Chemistry & Physics

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Hydrothermal polymerization (HTP) is a benign and inherently green synthetic approach to synthesize highly crystalline polyimides (PIs) in nothing but high‐temperature water (HTW). In a typical HTP experiment, highly crystalline PI microparticles of sheet‐like as well as flower‐like morphology are obtained. Within this contribution, the effect of four additives (PEG400, PEG8000, P123, CTAB) on the crystallinity and morphology of the PI poly(p‐phenylene pyromellitimide) is investigated. From the experiments performed, it becomes evident that the type as well as the concentration of additive heavily influences morphology. However, even the highest tested concentration of additive (67 g L−1 of PEG8000) does not lead to a change in average crystallinity, as determined from powder X‐ray diffraction. Hence, this approach provides a straightforward method to intentionally tune PI particle morphology without losing the outstanding materials properties generated by the high crystallinity obtained via HTP. Additionally, a hypothesis regarding the poly(ethylene glycol)‐induced morphology alteration is presented.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exerting Additive‐Assisted Morphological Control during Hydrothermal Polymerization

Taublaender

Reiter

Unterlass

2017

Macro Chemistry & Physics

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“…This monomer salt is then further dissolving and polymerizing to the PI (Scheme A). Alternatively, the monomer salt can be prepared prior to HTP, which is advantageous as it presents a precursor of ideal 1:1 stoichiometry that is necessary for obtaining high conversion and degrees of polymerization according to Carothers' law . Aside from the benign polycondensation conditions, HTP yields PIs of outstanding crystallinity, and is referred to as geomimetic polymerization .…”

Section: Introductionmentioning

confidence: 99%

Design Strategies in Hydrothermal Polymerization of Polyimides

Baumgartner

Bojdys

Skrinjar³

et al. 2016

Macro Chemistry & Physics

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Hydrothermal polymerization (HTP) is a technique to synthesize highly crystalline polyimides in solely water. The process involves monomer salt intermediates also able to undergo other polymerizations during the HTP experiment: sub‐hydrothermal polymerization (sHTP) and solid‐state polycondensation (SSP). Both processes yield semicrystalline polyimides at best. This is widely believed to result from irreversible bond‐formation and the incorporation of conformational defects during chain growth. Here, microwave‐assisted HTP is used, allowing for controlling the heating time to the reaction temperature, and thus to strongly reduce sHTP. Moreover, we show that highest crystallinity can be obtained in the higher hydrothermal regime (≈200 °C), and synthesize two polyimides of sufficient crystallinity to refine their crystal structures from powder X‐ray diffraction data. This study brings us one step closer to a general picture and rational design of the hydrothermal synthesis of polyimides.

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“…[1][2][3][4] In general, aromatic polyimides are usually obtained by imidizing the aromatic poly(amic acid) precursors, which were obtained from anhydride monomers and amine monomers. 9,10 Compared with the classical polycondensation methods of aromatic polyimides, hydrothermal process benefits one distinct advantage deemed to be the nontoxic solvent. Recently, some researchers have reported the preparation of aromatic polyimides by hydrothermal techniques, which are a common approach for the synthesis of highly inorganic materials.…”

Section: Introductionmentioning

confidence: 99%

Green facile fabrication of polyimide by microwave‐assisted hydrothermal method and its decomposition dynamics

Zhuo

Tang

Zhao

et al. 2019

J of Applied Polymer Sci

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A microwave-assisted hydrothermal technique was proposed in this work to fabricate polyimide using ethanol as sole solvent, and the decomposition dynamics of the resulting polyimide was also investigated. The preparation process involved that the ammonium carboxylic ester intermediates could be able to cyclize de-alchoholation, thus generating imide ring structures. The obtained polyimide exhibited excellent thermal properties. Specifically, the glass transition temperature of the polyimide was around 267.8 C, and it begun to decompose gradually from about 550 C. A novel method was employed to choose the dynamics model according to the linear correlation between g(α) and 1/β. As a result, the three-dimensional diffusion (Jander) model was much more suitable for the thermal decomposition process of the resulting polyimide, and the thermal decomposition mechanism was explained by using the model. The apparent activation energy (E a ) values calculated by Flynn-Wall-Ozawa and Kissinger methods were similar showing the same variation tendency. Furthermore, a series of fitting polynomials for E a and pre-exponential factor (A) values were achieved to reflect the trend more accurately. The dynamics results revealed that the decomposition process was complex and could be regarded as multistep reactions.

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Towards a general understanding of hydrothermal polymerization of polyimides

Abstract: Hydrothermal polymerization (HTP) yields highly crystalline polyimides. A general picture of the mechanisms leading to crystallinity and morphology is provided.

Cited by 48 publications

References 24 publications

Exerting Additive‐Assisted Morphological Control during Hydrothermal Polymerization

Exerting Additive‐Assisted Morphological Control during Hydrothermal Polymerization

Design Strategies in Hydrothermal Polymerization of Polyimides

Green facile fabrication of polyimide by microwave‐assisted hydrothermal method and its decomposition dynamics

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