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Integration of acrylate polymer in sol-gel silica depending on their molecular weight Anthony Maon 1 1 Imperial College of London, UK Confidential :) Anthony Maon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel

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SLIDE 1

Integration of acrylate polymer in sol-gel silica depending 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

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SLIDE 2

Outline

1

Introduction Aims 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

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SLIDE 3

introduction Acrylate polymer can have different chemical properties and architecture

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

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SLIDE 4

Aim & objectives Aim How cross linking acrylate polymers are integrated in the silica matrix depending on their molecular weight

  • bjectives

Use the Regulated free radical polymerization Characterised the polymerisation reaction Characterise the hybrid

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 4 / 17

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SLIDE 5

Tageted Mw DPni R0 (x10−3) 30kDa 120 8.3 15kDa 60 16.6 7.5kDa 30 33.1 2.5KDa 10 99.4 Cmonomer=1mol.L−1 C0= ninitiator

nmonomer = 1.5%

R0=

nCTA nmonomer = variable

T0= ntrioxane

nmonomer = 5%

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 5 / 17

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SLIDE 6

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

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SLIDE 7

Chemical Structure : NMR

NMR

1H ppm 13C ppm

0.5 1 1.5 2 2.5 3 3.5 4 15 30 45 60 75

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 7 / 17

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SLIDE 8

Chemical Structure : NMR

0.5 1 1.5 2 2.5 3 3.5 4

30kDa 15kDa 7.5kDa 2.5kDa

1H NMR (ppm)

Intensity (a.u.)  

  



Atatic (mr) / Syndiotatic (rr) Tageted Mw tacticity (rr/mr) 30kDa 1.85/1 15kDa 1.80/1 7.5kDa 1.70/1 2.5KDa 1.44/1 An increase of the tacticity of the polymer is observed with the increase of the molecular weight.

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 8 / 17

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SLIDE 9

Chemical Structure : FTIR

650 850 1050 1250 1450 1650 Wavenumber (cm−1) Absorbance (a.u.)

1725 C=O 1466 C−H2 scissor bend 1400 C−H3 sym bend 1270 C−O strech out of phase 1239 strech C−O in phase 1190 Si−OCH3 1140 C−O + skeletal C−C 1070 Si−OCH3 981 CH3 rocking 845 Si−C 791 CH3 rocking

30kDa 15kDa 7.5kDa 2.5kDa

1000 1500 2000 2500 3000

30kDa 15kDa 7.5kDa 2.5kDa

Wavenumber (cm−1) Absorbance (a.u.)

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 9 / 17

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SLIDE 10

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

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SLIDE 11

Synthesis method : Inorganic weight percent

The mass of the polymer mPoly is known. The mass of TEOS, mTEOS, used, is calculated to get a final Inorganic weight percent

  • f Iw .

      



      



             







 

     Inorganic Weight % Iw =

mSiO2 +mSiO1.5 mSiO2 +mSiO1.5 +mOrganic ⇒ nTEOS = Iw 1−Iw .nPolymer .Mw.Organic −nPolymer .Mw.SiO1.5 Mw.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

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SLIDE 12

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 which counts only 3 alkoxy groups where TEOS has 4. Therefore, H2O and the catalyst are introduced relatively to the number of mole

  • f alkoxy group.

Ratio definition nAlkoxy = 3.nPolymer + 4.nTEOS RH2O =

nH2O nAlkoxy ; RCatalyst = nCatalyst nAlkoxy

; REtOH =

nEtOH nAlkoxy

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 0.258 HCL 1M 1 0.32 0.322 TEOS 208.33 0.933 5 1.123 Alkoxy group

  • 32.2
  • Anthony Maçon (PhD)

Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 12 / 17

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SLIDE 13

Chemical Structure : FTIR

650 850 1050 1250 1450 1650 Wavenumber (cm−1) Absorbance (a.u.)

30kDa 15kDa 7.5kDa 2.5kDa

650 850 1050 1250 1450 1650 Wavenumber (cm

−1)

Absorbance (a.u.)

30kDa 15kDa 7.5kDa 2.5kDa

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 13 / 17

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SLIDE 14

Thermoanalysis

125 250 375 500 625 750 10 20 30 40 50 60 70 80 90 100 Temperature (oC) Mass loss (%)

2.5kDa 7.5kDa 15kDa

125 250 375 500 625 750 2 4 6 8 10 12 Temperature (oC) DSC (mW.mg−1) −−> exo

2.5kDa 7.5kDa 15kDa

Composition TGA DSC Residual mass inflection pt (oC) exothermic peaks(oC) (%) 2.5kDa 366.8 377.2 &394.5 28.9 I29 7.5kDa 368.8 313.8 & 365 31.6 15kDa 363.2 302.7 & 368.2 29.5 2.5kDa 349.3 359 & 377.5 48.5 I50 7.5kDa 336.4 310.9 & 336.4 50.7 15kDa 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

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SLIDE 15

Thermoanalysis 50 100 150 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

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SLIDE 16

Mechanical properties Nonoindentation using berckvich indenter.

2.5KDa 15KDa 3 3.5 4 4.5 5 Reduced young modulus (GPa)

50% inorganic

500 1000 1500 2000 2500 10 20 30 40 50 60 Displacement (nm) Force (mN)

50% inorganic, 2.5kDa 50% inorganic, 15kDa

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 16 / 17

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SLIDE 17

The end Thanks for your attention

Anthony Maçon (PhD) Integration of synthetic polymer in sol gel silica matrix Sol gel meeting 17 / 17

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SLIDE 18

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

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SLIDE 19

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

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SLIDE 20

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

980 970 960 950 940 930 920 200 400 600 800 1000 500000 1000000 1500000 2000000 2500000 3000000

Intensity (counts) Data points Si+ (27.9915) Ca+ (39.9852) total (Intensity (Raw))

IEF Marie Curie – HABER

SIMS

40 %CAR 60 %SiO2Ca2+

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SLIDE 21

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+

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SLIDE 22

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

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SLIDE 23

R O O O Si OH OH O H OH

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 Si OH OH O H O H O H

a b c d' e’ f’ diol MeOH c

Courtesy of Louise

d

O Si O O O O CH3 CH3 C H3

a 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

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SLIDE 24

HSQC of functionalised with GPTMS Alginate

3 days functionalisation

e

a b f1 f2 MeOH

12 h functionalisation

c

??

O Si OH OH O H O H O H

a b c d' e’ f’

Diol

R O O O Si OH OH O H OH

e’’ f’’

e f’ e’ d1 d’ d2 a b f2 f1 MeOH e f’ e’ d1 c d’ d2 Alg Functionalised GPTMS

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SLIDE 25

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

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SLIDE 26

Dissolution study of alginate-silica hybrids

Dissolution study in Tris

20 40 60 80 100 120 140 160 50 100 150 200 250 300 350 µg/ml 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&not&

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

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SLIDE 27

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

slide-28
SLIDE 28

ATR-FTIR of alginate modified with APTES

1900 1800 1700 1600 1500 1400 1300

NH2 NH C=O (amide) C=O COO

  • COO
  • COO
  • Alginate

A PTES + Alginate

Absorbance 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

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SLIDE 29

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