Chimica Inorganica III - chimica.unipd.it · -TGA-DSC (on 3 selected samples, PMMA and 2 hybrids) → comparison hybrid/PMMA. Silvia Gross - Chimica Inorganica III - Laurea Magistrale

Silvia Gross - Chimica Inorganica III - Laurea Magistrale in Chimica

Istituto di Scienze e Tecnologie Molecolari

ISTM-CNR, Università degli Studi di Padova

e-mail: [email protected]

Silvia Gross

La chimica moderna e la sua comunicazione

Dipartimento di Scienze Chimiche

Università degli Studi di Padova

e-mail: [email protected]

http://www.chimica.unipd.it/silvia.gross/

Silvia Gross, Mara Natile

Chimica Inorganica III

Lezioni propedeutiche al laboratorio

a.a. 2018-2019


Experiments

0.Procedure speciali nell’attività di laboratorio (tecnica di Schlenk, polimerizzazione UV,

sintesi solvo- ed idrotermale)

1.Sintesi di oxocluster tetranucleari di zirconio Zr4

2.Sintesi di materiali ibridi organici-inorganici reticolati da oxocluster di zirconio Zr4

3.Sintesi di ferriti mediante coprecipitazione di ossalati e mediante sintesi idrotermale

4.Sintesi e caratterizzazione spettroscopica dei complessi di vanadile V(I) (d1)

5.Chimica di coordinazione del Cu(II)

6.Sintesi biogenica di nanostrutture colloidali di argento

7.Complesso polinucleare termocromico di Cu(I)

8.Polimeri di coordinazione a base di Cu(II)


2. Synthesis of Zr-hybrid materials

Polymerisation



basic concept

incorporation of a basic structure of one material (guest) in a second one

(matrix) combination and synergy of the properties

+



polymer

flexibility

formability, processability

low density, lightness

inorganic

hardness

thermal stability

high refractive index



guest host

(matrix)

example of

guest

inorganic organic nanoparticles,

whiskers, fibers,

lamellae, clusters

organic inorganic polymers,

biomolecules,

enzymes, dyes



guest host

(matrix)

example of

guest

inorganic organic nanoparticles,

whiskers, fibers,

lamellae, clusters

organic inorganic polymers,

biomolecules,

enzymes, dyes



Class I Class II



simple embedding of organic and inorganic compounds only weak bonds

(van der Waals, hydrogen) link the two phases

A: dissolution of molecules - dyes, catalytically active metal complexes,

sensor compounds, biomolecules, enzymes, antibodies - or dispersion of particles

in the precursor solution: the gel matrix is formed around them and traps them

B: sol-gel processing of alkoxides performed in a solution of an organic polymer,

the inorganic network and the organic network interpenetrate but they are not

bonded to each other

Class I



Class IIthe two constituents are linked together through strong (covalent or ionic)

chemical bonds. Examples are

1- in silicate systems it is possible to use R’Si(OR)3 molecules as sol-gel

precursors. In the organically substituted derivatives the R’ group is bonded

through a Si-C link to the network-forming inorganic part of the molecule

Since Si-C bonds are hydrolitically stable, the organic groups are retained

in the final materials.

2- interpenetrated dual network by formation of chemical bonds

3- polymers reinforced by covalently bonded inorganic clusters



1. overcoming of the structural limits of conventional materials (polymers, ceramics, metals

etc.)

2. fine tuning of the properties through variation of:

- composition

- microstructure

- interaction at the interface

3. design of multifunctionality (combination of functionalities)

4. infinite compositional variability

advantages of I/O hybrid materials



Fundamental textbooks

Clement Sanchez, Pedro Gomez Romero

Functional Hybrid Materials

VCH Wiley, Weinheim, Germany 2004

Ulrich Schubert, Nicola Hüsing

Synthesis of inorganic materials

VCH Wiley, Weinheim, Germany, 2004

Guido Kickelbick

Hybrid Materials

VCH Wiley, Weinheim, Germany 2006



Polymerisation



Experimental parameters

Cluster type (M= Zr, Hf, Ta)

Cluster: monomer molar ratios (1: 25, 1: 50, 1: 100, 1: 200)

Polymerisation type (photo- or thermoactivated)

Monomer nature (MMA, MA, styrene, HEMA)

Nature of the final samples (thin films or bulk specimen)

Film deposition method (spray, spin, dip-coating)

+ monomer hybrid



free radical polymerisation



free radical

polymerisation



free radical polymerisation

photoactivated thermoactivated



UV radiation photoinitiator

reactive species monomer, oligomer

cured polymer



Initiation RM.

R.h

IM

Propagation RM.i + M RM

.i+1

RM.n RM

.k

+ RMn+k R

RMn

+ RMk

Termination

photochemical initiators



photochemical initiators: requirements

• High photosensitivity in the range of wavelength 300–400 nm.

• Good solubility and reactivity in the oligomer–monomer system.

• Guarantee of the stability during storage and environmental tests



photochemical initiators: requirements

C

O

C

OR

h .C

O

C

OR

.+

..

H

C

O

C

OR'

OCHR

. .+C

O

C

OR'

OCH2R

C

O

C

OR'

OCH2R

C

O

C

R

R

OH C

O

C

R

R

OH+..

C P

O O

C

O

P

O

+..

Benzilketals

Dialkoxyacetophenones

Hydroxyalkylphenyl ketones

Benzoyol phosphine oxides



photochemical

initiators: examples



Chemical identity Melting point ( °C)UV/VIS absorption peaks (nm) in

methanol

IRGACURE-184 1-Hydroxy-cyclohexyl-phenyl-ketone MP 45–49 246, 280, 333

IRGACURE-651Alpha-dimethoxy-alpha-

phenylacetophenoneMP 64–67 254, 337

IRGACURE-819Bis (2,4,6-trimethylbenzoyl)-

phenylphosphineoxideMP 127–133 370, 405

IRGACURE-9072-Methyl-1 [4-(methylthio)phenyl]-2-

morpholinopropan-1-oneMP 70–75 232, 307



high-intensity, medium pressure mercury vapor lamp

The emission from this type of unit is rich in UV radiation in the 200-400 nanometer band

This energy is in the area suited to the proper and complete curing as most

UV curable products incorporate photoinitiators which react within this bandwidth

UV lamps



UV lamps: emission spectrum



UV lamps: depth of curing



Lampade UV e sicurezza (vedere sezione “Sicurezza”

sito didattica docente)

Norme Europee e Norme principali

EN166 requisiti di base

EN167 metodi per test ottici

EN168 metodi per test non ottici.

EN169 filtri per saldatura

EN170 filtri per UV

EN171 filtri per IR

EN172 filtri solari per utilizzo industriale

Quando si usa la lampada UV:

- No mani nude sotto la lampada (400 W)

- Sempre occhiali protezione UV forniti



REFERENCES ON PHOTOPOLYMERISATION

“Radiation Curing in Polymer Science and technology”, Vol. I-IV, J.P. Fouassier, J.F. Rabek

ed., Elsevier London, 1993.

“Photopolymerization and Ultraviolet Curing of Multifunctional Monomers”, C. Decker,

Materials Science and technology, H.E.H. Meijer ed., VCH, Germany, 1997.

“Radiation Curing Science and Technology”, S.P. Pappas Ed., Plenum Press, New York, 1992.

“Photoinitiators for Free Radical Cationic and Anionic Photopolymerization”, J.V. Crivello, p.

329, G. Bradley ed., Wiley, New York, , 2nd ed., 1998.

“Photopolymerization of surface coatings“ C.G. Roffey, Wiley, New York, 1982.

“Photoinitiated Crosslinking Polymerization” C. Decker, Progress in Polymer Science, Vol. 21,

593, 1996.

“Cationic Photopolymerization” R. Lazauskaite, J.V. Grazulevicius, Handbook of

Photochemistry and Photobiology, H.S. Naiwa ed., Vol.2, Chapt. 7, p. 335, American Scientist

Publisher, New York, 2003.

“The discovery and Development of onium salt cationic photoinitiators” J.V. Crivello, Journal

of Polymer Science Polymer Chemistry, Vol. 37, p. 4241, 1999.



photopolymerisation kinetics


2. characterisation of hybrid materials

- FT-IR (on PMMA and hybrid material)

- swelling (on PMMA and hybrid material)

- TGA-DSC (on 3 selected samples, PMMA and 2 hybrids)

→ comparison hybrid/PMMA



swelling behaviour

the swelling behaviour in polymeric materials is generally used for the

characterization of elastomeric networks

Operative modeThe simple experiment consists in completely immersing a sample in a solvent and in

waiting until swelling equilibrium occurs. An accurate value can be obtained only with

samples which have been carefully extracted to remove soluble materials. The

swollen network is reweighted and the weight percentage increase provides the

extent of swelling and a good phenomenological characterization of the polymer.

The swelling index (Isw) can be calculated according to:

Isw (g/g) = (wet weight - dry weight)/ dry weight

and it corresponds to the weight of the solvent that the dry material is able to absorb



swelling behaviour

Swelling results from two competitive

thermodynamic phenomena:

(i) the entropy increase of the system network-solvent due to the introduction

of small particles as diluent;

(ii) the decrease of the polymeric chain entropy due the isotropic expansion.

Equilibrium is reached as soon as the maximum swelling is obtained.

A statistical treatment of Gibbs free energy function, DG, affords a qualitative

relationship between the swelling and the degree of the crosslinking

density, which can be profitably used to characterize polymeric materials.



swelling behaviour

low solvent uptake

low swelling

high crosslinking



swelling behaviour

2.0

1.5

1.0

0.5

clu

ste

r p

rop

ort

ion

[m

ol

%]

4.54.03.53.02.52.01.51.00.50.0

solvent uptake [g solvent/g polymer]

Z r4

O2

(O M c )1 2

T a4

O4

(O M c )4

(O Et )8

T i4

O2

(O P ri)

6(O M c )

6 Ta4O4(OEt)8(OMc)4

Ti4O2(OPri)6(OMc)6

Zr4O2(OMc)12

OMc = methacrylate


thermogravimetric analysis

Operative mode

continuous weighting of a small sample (ca 10 mg) in a controlled atmosphere (e.g.,

air or nitrogen) as the temperature is increased at a programmed linear rate

typically at a constant rate, in the range 1-20°C/min

an electromagnetic balance having a typical sensitivity of 0.1 micrograms is used to

measure the weight variations

Possibility to interface the thermal analysis equipment with other instruments (IR,

GC-MS…)

measures the change of weight of a sample as a function of

either time or temperature



100

80

60

40

20

0

wei

gh

t lo

ss (

%)

800700600500400300200100

temperature (°C)

DT=80°C

PMMATa4PMMA50Ta4PMMA100Ta4PMMA200



Application to polymer science and hybrid materials

• TA is a very simple technique for quantitatively analysing the

filler/inorganic content of a polymer compound (Zr-based oxocluster in

PMMA ZrO2)

• it allows to investigate the decomposition path of the materials as well

as the actual content of inorganic component

• purity control

• stability as a function of the inorganic content

thermogravimetric analysis


Documents

Chimica Inorganica III - chimica.unipd.it · -TGA-DSC (on 3 selected samples, PMMA and 2 hybrids) → comparison hybrid/PMMA. Silvia Gross - Chimica Inorganica III - Laurea Magistrale