e della Sostenibilit Ambientale Universit di Parma INSTM UdR Parma - - PowerPoint PPT Presentation

Enrico Dalcanale Dipartimento di Scienze Chimica, della Vita e della Sostenibilità Ambientale Università di Parma INSTM – UdR Parma

E-mail:enrico.dalcanale@unipr.it Homepage: www.dalcanalegroup.it

MIPOL 2017, 15-16 Febbraio 2017

The application side: Polymer blending Self-diagnostic polymers The basic science: Host-guest homopolymers

Bond reversibility brings in new properties: self-healing low process viscosity Meijer et al., Science, 1997, 278, 1601.

Hydrophobic interactions:

• Cyclodextrins
• Cucurbiturils

Specific host-guest interactions:

• Crown ethers
• Calixarenes
• Cavitands

Requirement for true polymerization: Ka>105

• F. Tancini, E. Dalcanale in Supramolecular Polymer Chemistry. Bridging Words

(A. Harada Ed., Wiley-VCH 2012, 71-93)

Tiiii[R1, R2, R3]

• Eur. J. Org. Chem. 2004, 451; Chem. Soc. Rev. 2007, 36, 695;
• Acc. Chem. Res. 2013, 46, 399

X-Ray of Tiiii•N-methyl pyridinium salt

JACS 2009, 131,7447

Crystal structure of Tiiii•sarcosine hydrochloride complex from MeOH/H2O PNAS 2012, 109, 2263; J. Am. Chem. Soc. 2016, 138, 8569

Homopolymers Copolymers

• Angew. Chem. Int. Ed. 2008, 47, 4504
• Chem. Eur. J. 2010, 16, 14313

MONOMER

Tiiii

STOPPER

TSiiii

X-Ray of TSiiii•CH3CN Crystal packing of TSiiii STOPPER TSiiii

Structure confirmed by NOESY -NMR and ESI-MS spectra.

Host-Guest Dimer K (M-1)

(4.0± 0.1) •107 ∆H

• 30.0 ± 0.1

T•∆S 13.4 ± 0.5 ∆G

• 43.6 ± 0.5

N 0.81 ± 0.01

Values in KJ mol-1 in CH2Cl2

CHCl3 Homopolymer I-, PM monomer = 1463, dn/dc =1.52 mM <N> MW 3.06 11 16140 4.18 12 17740 5.06 13 19280 6.9 15 22410 10.2 18 26270 14.5 20 28650 No aggregation in DMA or acetone

Minimal aggregation in CHCl3 (2-3 units max at high conc.)

n

Static Light Scattering measurements of the weight-average molecular weight

• f linear polymer

We performed Static Light Scattering in a concentration range between 1 g/L (0.7mM) and 15 g/L (10mM) reaching degree of polymerization dp=18 (>27000 Da).

n

10000 12000 14000 16000 18000 20000 22000 24000 26000 28000 5 10 15 20 MW Concentration g/L

n-x

polymer MW control by chain stopper addition polymer growth by increasing the concentration

Monomer length from X-ray: 15 Å Stopper length via PGSE in acetone-d6: 14.9 Å

In CH3CN

1H-NMR assembly-disassembly in CDCl3

Star shaped polymer

g/L MW homopolymer MW star shaped polymer Ratio 1,04 11850 46210 3,8996 2,05 13490 41600 3,0838 4,10 15940 49700 3,1179

+

n n n n n

Static Light Scattering measurements of the weight-average molecular weight of star-branched polymer

Problem: minimize interfacial energy to reduce the propensity for phase separation

Macromolecules 2014, 47, 632

Guanosine

• T. Park, S. C. Zimmerman, J. Am. Chem. Soc. 2006, 128, 11582

Molecular Level Mixing Driven by H-Bonding

2,7-diamido- 1,8-naphthyridine

Ka = 5 . 107 M-1

Mn Mw PDI 27300 40000 1.47

Ratio m/n = 40 (2.5% molar ratio) verified by 1H NMR and N elemental analysis

Mn Mw PDI 20800 27100 1.30

Ratio m/n = 40 (2.5% molar ratio) verified by 1H NMR and P elemental analysis

1) 10 20 30

0.25 eq. Monotopic Guest 0.5 eq. Monotopic Guest 1.25 eq. Monotopic Guest

8.70 10.22

Host copolymer

(f1) 10.0 .0

CDCl3 RT

Sample Mn mol/mL Tg Rough (Rq) PBMA 21500 9.2∙10-4 26°C 8.16nm Sample Mn mol/mL Tg Rough (Rq) PS 21000 9.2∙10-4 95°C 10.99nm

T= 12°C

mixture 1:1 PS+PBMA PBMA PS T= 12°C

Chen et al. Langmuir 2002, 18, 1302 Zimmerman et al. JACS 2006, 128, 11582

Substrate: silicon oxide

Sample Tg °C PS 95 PBMA 26 PS- PBMA 1.1 26 96

Sample Mn mol/mL Tg Rough (Rq) PBMA- guest 27300 9.2∙10-4 20°C 12.08nm Sample Mn mol/mL Tg Rough (Rq) PS-host 20800 9.2∙10-4 97°C 6.45nm

T= 12°C

+

1:1 molar ratio

+

1:1 molar ratio

Sample Tg °C PS-host 97 PBMA-guest 25 PS-host + PBMA-guest 1:1 40 PS-host + PBMA-guest 2:1 58 PS-host + PBMA-guest 1:2 32

1:1 mixture PS-host+PBMA-guest NOT METHYLATED

PS-PBMA

PS-host + PBMA-guest Not methylated PS-host + PBMA-guest

White = PS Brown = PBMA 20 nm height difference

Sample Tg °C PS-host 97 PBMA-guest NOT methylated 20 PS-host + PBMA-guest NOT methylated 1.1 20 95

Electrochemical Stimulus Solid-liquid interface

Soft Matter 2016, 12, 5353-5358

1 V/min 1° 2°

All scans after the first one are reproducible

Cathodic Peak Reference electrode: Ag/AgCl ; Auxiliary electrode: Pt Working electrode: deposited blend Solvent: water; Supporting electrolyte: NaCl 0,1 M Scan rate: 200mV/s

Average roughness: 1.91 nm Average roughness: 11.1 nm

Assembled copolymer coated

• n gold plate before reduction

at 90°C Disassembled copolymer coated gold plate before reduction at 90°C

Nota Bene: no disassembly below PS–Host Tg

• 0,8 V 90 °C

AFM non-contact mode

PS-Host/PBMA-Py PS-Host/PBMA-Py reduced at 90°C

Topography Phase

AFM non-contact mode

Larger and deeper segregation zones appear

AFM tapping mode

is a powerful tool in materials science Functional polymers require a molecular level understanding and control of the weak interactions in the and at leading to Key features of cavitand-based materials are:

+ + + +

Francesca Tancini Roger Mbanda Daniele Masseroni

Marco Dionisio Andreas Früh

Crystal structures University of Trieste (Synchrotron)

• S. Geremia
• N. Demitri

DIC measurements University of Parma

• R. Brighenti

Polymers MW characterization University of Pisa

• G. Ruggeri/ L. Ricci

Electrochemistry University of Parma

• M. Giannetto

AFM measurements University of Parma

• D. Orsi
• G. Cristofolini

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