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Integration of acrylate polymer in sol-gel silicadepending on their molecular weight
Anthony Maçon1
1Imperial College of London, UK
Confidential :)
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 1 / 17
Outline
1 IntroductionAims and Objectives
2 Polymer synthesis and characterisation
3 Polymer Characterisation
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 2 / 17
introduction
Acrylate polymer can have different chemical properties andarchitecture
Monomer organisation Polymer Architecture Homopolymer Statistical Copolymer Block Copolymer
Brush
Star Branched
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 3 / 17
Aim & objectives
AimHow cross linking acrylate polymers are integrated in the silica matrix
depending on their molecular weightobjectives
Use the Regulated free radical polymerizationCharacterised the polymerisation reactionCharacterise the hybrid
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 4 / 17
Tageted Mw DPni R0 (x10�3)30kDa 120 8.315kDa 60 16.67.5kDa 30 33.12.5KDa 10 99.4
Cmonomer =1mol.L�1
C0= ninitiatornmonomer
= 1.5%R0= nCTA
nmonomer= variable
T0= ntrioxanenmonomer
= 5%Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 5 / 17
Chain Transfer constant
(1
DPn)i = CT
[T ]
[M]=
d [T ]
d [M]
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 6 / 17
Chemical Structure : NMR
NMR
1H ppm
13C
pp
m
0.511.522.533.54
0
15
30
45
60
75
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 7 / 17
Chemical Structure : NMR
0.511.522.533.54
30kDa
15kDa
7.5kDa
2.5kDa
1H NMR (ppm)
Inte
nsi
ty (
a.u
.)
Atatic (mr) / Syndiotatic (rr)
Tageted Mw tacticity (rr/mr)30kDa 1.85/115kDa 1.80/17.5kDa 1.70/12.5KDa 1.44/1
An increase of the tacticity of the polymer is observed with theincrease of the molecular weight.
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 8 / 17
Chemical Structure : FTIR
6508501050125014501650Wavenumber (cm
!1)
Ab
sorb
an
ce
(a
.u.)
1725
C=O
1466
C−H
2 sci
ssor
ben
d
1400
C−H
3 sym
ben
d
1270
C−O
stre
ch o
ut o
f pha
se12
39 s
trech
C−O
in p
hase
11
90 S
i−O
CH
311
40 C−O
+ s
kele
tal C−C
1070
Si−
OC
H3
981
CH 3 ro
ckin
g
845
Si−C
791
CH 3 ro
ckin
g
30kDa
15kDa
7.5kDa
2.5kDa
10001500200025003000
30kDa
15kDa
7.5kDa
2.5kDa
Wavenumber (cm!1
)A
bso
rba
nc
e (
a.u
.)
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 9 / 17
Size of the polymer : GPC & Dynamic Light Scattering
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 10 / 17
Synthesis method : Inorganic weight percentThe mass of the polymer mPoly is known. The mass of TEOS, mTEOS , used, is calculated to get a final Inorganic weight percentof Iw .
Inorganic Weight %
Iw =mSiO2
+mSiO1.5mSiO2
+mSiO1.5+mOrganic
) nTEOS =
Iw1�Iw
.nPolymer .Mw.Organic�nPolymer .Mw.SiO1.5Mw.SiO2
1 mol of TEOS gives 1 mol of SiO2 and 1 mol of polymer gives 1 mol of SiO1.5
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 11 / 17
Synthesis method : Ratio
The classical definition of the R ratio can’t be used in the study. Network precursors are also introduced by the polymer whichcounts only 3 alkoxy groups where TEOS has 4. Therefore, H2O and the catalyst are introduced relatively to the number of moleof alkoxy group.
Ratio definition
nAlkoxy = 3.nPolymer + 4.nTEOS
RH2O =nH2O
nAlkoxy; RCatalyst =
nCatalystnAlkoxy
; REtOH =nEtOHnAlkoxy
Table : Reagent which is needed for 1g of polymer and RH2O=1, RCatalyst =0.01, REtOH =1
Reagent Mw (g.mol�1) D (g.mL�1) n (mmol) V (mL)Ethanol 46.07 0.789 32.2 1.88
H2O 18.01 1 14.3 0.258HCL 1M 1 0.32 0.322
TEOS 208.33 0.933 5 1.123Alkoxy group - - 32.2 -
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 12 / 17
Chemical Structure : FTIR
6508501050125014501650Wavenumber (cm−1)
Absorbance (a.u.)
30kDa15kDa7.5kDa2.5kDa
6508501050125014501650Wavenumber (cm−1)
Abs
orba
nce
(a.u
.)
30kDa15kDa7.5kDa2.5kDa
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 13 / 17
Thermoanalysis
125 250 375 500 625 7500
102030405060708090
100
Temperature (oC)
Mas
s los
s (%
)
2.5kDa7.5kDa15kDa
125 250 375 500 625 7500
2
4
6
8
10
12
Temperature (oC)
DSC
(mW
.mg−
1 ) −−>
exo
2.5kDa7.5kDa15kDa
Composition TGA DSC Residual massinflection pt (oC) exothermic peaks(oC) (%)
2.5kDa 366.8 377.2 &394.5 28.9I29 7.5kDa 368.8 313.8 & 365 31.6
15kDa 363.2 302.7 & 368.2 29.52.5kDa 349.3 359 & 377.5 48.5
I50 7.5kDa 336.4 310.9 & 336.4 50.715kDa 302.1 296.2 & 315.1 52.5
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 14 / 17
Thermoanalysis
0 50 100 1500
10
20
30
40
50
60
70
Time (min)
[Si]
(µg.
ml−
1 )
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 15 / 17
Mechanical properties
Nonoindentation using berckvich indenter.
2.5KDa 15KDa 3
3.5
4
4.5
5
Redu
ced
youn
g m
odul
us (G
Pa)
50% inorganic
0 500 1000 1500 2000 25000
10
20
30
40
50
60
Displacement (nm)
Forc
e (m
N)
50% inorganic, 2.5kDa50% inorganic, 15kDa
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 16 / 17
The end
Thanks for your attention
Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 17 / 17
1
Silica – polysaccharide hybrids for bone tissue regeneration
Sol-gel meeting
18th April 2013
Yuliya Vueva
Intra-European Fellowship for career development (IEF) - Marie Curie
2
Objectives
The aim of the project is to create new bioactive porous hybrid scaffolds that fulfil all the criteria of a scaffold for bone regeneration
Preparation and characterization of hybrids by incorporating in the sol-gel process natural polysaccharide polymers
(Carrageenans, Alginates, Celluloses)
naturally occurring, biodegradable, nontoxic
used in the food industry and in medic, in the field of drug delivery
provide an alternative and novel method for introducing calcium into the hybrids
The principle challenge will be to produce hybrid materials with covalent bond between the organic (polysaccharide) and inorganic (silica) part of the hybrid with controllable degradation and mechanical properties matching the host bone
IEF Marie Curie – HABER
Carrageenans
Carrageenans are sulphated linear polysaccharides of D-galactose and 3,6-anhydro-D-galactose extracted from certain red seaweeds
Iota -carrageenan
Interesting for hybrids application
• Iota-carrageenan produces soft and elastic gels • Carrageenans are anionic polyelectrolytes which gives the posibility of Ca2+ to be incorporated in the hybrid network Carrageenan Issues
• Solubility problems - soluble only in water at 70oC; depending on the molecular weight; 10 mg/ml maximum • Viscosity of solution - difficult to obtain homogenous gels
• Modification with Si coupling agents is difficult due to the solubility issues - modification with GPTMS could be performed only in heterogenous conditions - the resultant product is insoluble
50.00 µm
Si+MC: 201; TC: 1.217e+007
200
190
180
170
50.00 µm
Ca+MC: 982; TC: 6.293e+007
980
970
960
950
940
930
920
0 200 400 600 800 1000
0
500000
1000000
1500000
2000000
2500000
3000000
Inte
nsity
(cou
nts)
Data points
Si+ (27.9915) Ca+ (39.9852) total (Intensity (Raw))
IEF Marie Curie – HABER
SIMS
40 %CAR 60 %SiO2Ca2+
Hybrids with alginates
4
Guluronic acid
Mannuronic acid
• Anionic polysaccharides derived from seaweeds • In presence of Ca2+ form gels crosslinked by complexation with Ca2+
• Contain carboxylic functional groups - Good potential for modification • Potential to produce hybrids with double crosslinking (chemical and physical ionic crosslinking)
Alginate
Crosslinking of alginate with Ca2+
5
Alginate modification with GPTMS
Fictionalisation reaction
Alginate
ester
Guluronic acid
Mannuronic acid
30 mg/ml Alginate in 0.01 M HCl
RSH > RNH2 > R2NH > RCOOH > SiOH >> ROH > H2O
Relative reaction rates of different functional groups toward epoxy groups
IEF Marie Curie – HABER
R
O
O O Si
OH
OH
OHOH
e’’
f’’
1H NMR
GPTMS + Alg 12h
GPTMS + Alg 3 days
Alginate
GPTMS in D2O/DCl
Alg
Alg Alg
Alg Alg
Alg
Alg Alg
Alg
f1 f2
O SiOH
OH
OHOH
OH a
b
c d' e’
f’ diol
MeOH c
Courtesy of Louise
d
O Si
O
O
OO
CH3
CH3
CH3a
b c d e
f GPTMS Functionalised GPTMS
pH ~ 5
Dioxane Diol PEO
Dioxane Diol PEO
f1
f2
Epoxide opening versus silica condensation during sol-gel hybrid biomaterial synthesis, Luca Gabrielli, Laura Russo, Ana Poveda, Julian R. Jones, et. DOI: 10.1002/chem.200
HSQC of functionalised with GPTMS Alginate
3 days functionalisation
e
a
b
f1 f2
MeOH
12 h functionalisation
c
??
O SiOH
OH
OHOH
OH a
b
c d' e’
f’ Diol
R
O
O O Si
OH
OH
OHOHe’’
f’’ e f’
e’ d1 d’ d2
a
b
f2 f1
MeOH
e f’ e’ d1
c
d’ d2
Alg
Functionalised GPTMS
8
Issues and conclusions
• Polymer concentration is not high enough to achieve suitable 1H and 13C NMR signals
• This is not clear if the covalent linkages are lost in the background along with the polymer signal or is no covalent coupling occurring
• The epoxy ring is not fully opened during fictionalisation of alginate at pH 5. The main compounds detected are diol, dioxane and PEO.
IEF Marie Curie – HABER
Dissolution study of alginate-silica hybrids
Dissolution study in Tris
0
20
40
60
80
100
120
140
160
0 50 100 150 200 250 300 350
µg/m
l
Time (h)
Si release
Alg2 Alg5 Alg10
Alg15 Alg0 300 500 700 900 1100 1300 1500 1700 Wavenumbers, cm-1
Alg0 0h
Alg0 672h
COO- C=O
300 500 700 900 1100 1300 1500 1700 1900 Wavenumbers, cm-1
Alg2 672 h
Alg2 0h
C=O$COO%$
Sample$with$GPTMS$GC2$$$
Sample$without$GPTMS$
• Early&release&of&silica&is&rapid&when&alginate&is¬&coupled&with&GPTMS.&&
• No alginate after 4 weeks in TRIS for the sample without GPTMS
• The samples coupled with GPTMS showed very weak bands corresponding to carboxylic groups of alginate
• Most of the polymer had dissolved after 4 weeks in Tris
IEF Marie Curie – HABER
Modification of Alginate with APTES
Reaction utilizing carbodiimide chemistry
H2N C2H5
C2H5 C2H5
N H
3C2H5OH EDC/NHS
amide bond
IEF Marie Curie – HABER
1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride
EDC NHS
N-Hydroxysuccinimide
ATR-FTIR of alginate modified with APTES
1900 1800 1700 1600 1500 1400 1300
NH2
NHC=O (amide)
C=O COO-
COO-COO-
Alginate
APTES + Alginate
Abs
orba
nce
a.u.
Wavenumbers, cm-1
APTES
C=O
NHS
Formation of amide bond
Preliminary study of the reaction of APTES with Alginate
pH = 6
After dialysis of Alginate-APTES solutions the APTES is still present in the solution. – Functionalised Alginate
Further work
• Optimization of reaction conditions for modification of Alginate with APTES
• Evaluation of substitution degree by ICP and NMR
• Optimization Alginate-silica hybrid synthesis