N

NN

N N

NN

O

O

*Not determined

Introduction:A novel series of microporous polymer networks (MPNs) has been synthesized by acid catalyzed Friedel-Crafts-type self-condensation. For this new MPNs different A2B4 and A2B2 fluorenone-based monomers with e.g. 2,7-bis(N,N-diphenylamino) A or 2,7-bis[4-(N,N-diphenylamino)phenyl] D substitution are used (Figure 1). One synthetic challenge is to generate the MPNs straightforward under mild reaction conditions including moderate processing temperatures[1] and without the use of transition metal catalysts.[2]

Figure 1: Chemical structures of the monomers A–J:

IfP

Conclusion: In summary, A2B4-type monomers with 2,7-bis(N,N-diphenylamino) A or 2,7-bis[4-(N,N-diphenylamino)phenyl] D substitution of the fluorenone cores quantitatively form MPNs with high SBET surface areas of up to 1400 m2 g-1 in a simple Friedel–Crafts-type self-condensation. 2,7-Disubstitution with N-phenyl-N-methylamino groups as well as 3,6-disubstitution give rise to drastically reduced SBET values except for the mixture of the two extended monomers I and J. Supercritical CO2 (sCO2) treatment can distinctly increase the porosity of the samples especially for MPNs made of binary monomer mixtures containing A and C or D. The supercritical CO2 treatment seems to stabilize an expanded pore structure corresponding to the swollen state of the polymer network. Further ongoing modelling studies may help to explain the strong influence of the substitution pattern at the fluorene core and the influence of the sCO2 treatment.

References:[1] R. S. Sprick, A. Thomas, U. Scherf, Polym. Chem. 2010, 1, 283-285.[2] E. Preis, C. Widling, U. Scherf, S. Patil, G. Brunklaus, J. Schmidt, A. Thomas, Polym. Chem. 2011, 2, 2186.

Monomer(s) SBET m2 g-1 SBET after CO2 washing

m2 g-1

Total pore volume cm3 g-1

[after CO2 washing]

A 1420 1243 1.31 [0.90]B 57 - 0.06A/B (1:1) 716 924 0.47 [0.53]C 228 - 0.16A/C (1:1) 718 1775 0.43 [1.26]B/C (1:1) 9 - 0,009D 1161 1394 0.80 [0.85]E 12 - 0.01F 16 - 0.02D/E (1:1) 9 - 0.01D/F (1:1) 372 - 0.28E/F (1:1) 14 - 0.02G 9 - 0.01H 18 - 0.02G/H (1:1) 3 - 0.01I 17 - 0.02J 163 - 0.30I/J (1:1) 947 1447 0.67 [0.97]A/D (3:1) 1081 1103 *A/D (1:1) 968 1748 0.77 [1.6]A/D (1:3) 1221 1408 *

The obtained MPNs show an intrinsic porosity due to their rigid, three-dimensional structure. They contain regularly arranged tetragonal carbons, which are connected via N,N-diphenylamine-3,4´-diyl (monomers A-C) or N,N - d i pheny lam ine -4 ,4 ´ -d i y l b r i dges (monomers G and H). More extended bridges, N-(4-biphen-3´-yl)-N-(phen-4-yl)amine or N-(4-biphen-4´-yl)-N-(phen-4-yl)amine, connect the tetragonal carbons of the MPNs made from monomers D-F and I/J. These monomer structures allow the formation of the cross-linked networks in a single reaction step. The observed high intrinsic porosity indicates an open network structure. The in situ generated 9,9-diphenylfluorene tectons support the formation of a rigid MPN.

Table 1: Characterization data for the MPNs of this study

Figure 3: Idealized structure of the MPNs of monomers A ( R = phenyl) and B (R = methyl)

Figure 4: Idealized structure of the MPNs of monomer C

Novel Synthetic Approaches towards Microporous Polymer Networks

C. Widling1, E. Preis1, U. Scherf1, J. Schmidt2, A. Thomas2

1Bergische Universität Wuppertal, Makromolekulare Chemie und Institut für Polymertechnologie, Gaußstr. 20 D-42119 Wuppertal, Germany2Institut für Chemie, Technische Universität Berlin, Englische Straße 20 D-10587 Berlin, Germany

N N

O

N N

O

N

O

N NO

N NO

NO

N N

O

N N

O

O

N N

O

N N

HGF I J

A B C D E

N NR R

NR

NR

N RN

N

NRN

N

NR

NR

NR

N R

NR

NR

R

R R

R

O

O

N NR R

O

A/B

CH3SO3H/ 1,2-C6H4Cl2

140°CN

O

C

CH3SO3H / 1,2-C6H4Cl2

140°C

Figure 2: Nitrogen physisorbtion isotherm of condensation product of monomers I/J (top) and A/D (bottom)