Moshe Herzberg - ilmar.org.il · SPM Sulfopropyl methacrylate MOETMA Methacryloyloxy ethyl trimethylammonium Polymer surface Co-graft-polymerization. MOETMA + SPM modification K 2S

Surface Properties of Graft-Copolymers Possesing Oppositely Charged Groups:Oppositely Charged Groups:

Mitigation of Microbial Biofilm Formation, mechanisms and applications

קו עם המושתלים שטח פני מטעןתכונות מנוגדות קבוצות בעלי פולימרים פולימרים בעלי קבוצות מנוגדות מטען-תכונות פני שטח המושתלים עם קו:ומניעת גידול ביופילם מיקרוביאליאפשריים ושימושים םמנגנונים ם אפשר מוש ם וש מנגנונ

Moshe HerzbergZuckerberg Institute for Water ResearchBlaustein Institutes for Desert Research,,Sede Boqer CampusBen Gurion University of the Negev

Contamination of water treatment and distribution systems

Phil Stewart / Peg Dirckx – The Center for Biofilm Engineering - MSU Phil Stewart / Peg Dirckx – The Center forPhil Stewart / Peg Dirckx The Center for

Biofilm Engineering - MSUPaper machine biofilms

Phototrophic biofilms on ship hullshulls

Marko Kolari, Helsinki University, Finland http://phobia.itqb.unl.pt/

Microbial biofilms

Bacteria form aggregates in a self produced EPS on membranes

Bulk Side

Membrane Side

Main antifouling strategy: Increased surface hydrophilicityhydrophilicity

Charged surfaces: Less favorable;

N h d h d hili tiNon-charged hydrophilic coatingSagle, Freeman et al., J Memb Sci (2009)Bryers et al., Biomaterials (2004)

Polyethylene-glycol

“Modern antifouling” – net charge = 0S Jiang et al Advanced Materials (2008)

glycol

S. Jiang et al., Advanced Materials (2008)Cheng et al., Angew Chem (2008)

An attractive method for fabrication of antifouling surface:Redox-initiated graft polymerization using hydrophilic monomers

Polymer brushes

K2S2O8, K2S2O5

S hi B lf d h k A t P l i 1998 J M b S i 1998

Benefits:

Sophia Belfer and her coworkers, Acta Polymerica 1998; J Memb Sci 1998

In aqueous solutions, room temperature Short reaction times (~ 30 mins) C i ll il bl d h t Commercially available and cheap reagents

Possible modification inside membranes used for water treatment (Belfer et al., 2004)

Generation of free radical in solution by the redox couple:couple:

Potassium persulfate

Potassium metabisulfitep metabisulfite

Bamford and K. Al-Lamee, Polymer (1994)

Disadvantages:Disadvantages:

• Grafting occurs on the surface as well as in solution

• Slow reaction time and high concentration is required•

Our approach:

Polymer surface

Co-grafting

ZwiterionicZwiterionic monomer

SPESPE(sulfo-betaine)

Objectives1 Fabricating anti-fouling polyamide or PVDF surfaces having1. Fabricating anti-fouling polyamide or PVDF surfaces having

increased wettability with minimal change in surface charge

2. Surface characterization, swelling, and reduced EPS adsorption f fof modified membranes

SPMSulfopropyl methacrylate

MOETMAMethacryloyloxy ethyl trimethylammonium

Polymer surface

Co-graft-polymerization

MOETMA + SPM modification

K2S2O8K S O

MOETMA

SPM

SO3N+ CH

CH3

K2S2O5SPM

ATR-FTIR spectrum:

C=O esterN+ CH3

CH3

Achieve high grafting yields of sulfo and ammonium !

Hydrophilicity – by water drop t t lcontact angle

MOETMA + SPM

Achieve dramatic increase in hydrophilicity (wettability) in all concentrations used!!

Electrostatic repulsions between negatively-charged sulfo and RO polyamide membrane:sulfo and RO polyamide membrane:

SSPM only:

RO Polyamidemembrane

MOETMA + SPM:SPM:

RO Polyamideymembrane

Zeta-potential of RO membrane surface after grafting

MOETMA + SPM

MOETMA only

+2 eV

-19 eV-19 eV

Graft Copolymerization On PVDF-coated surface using SPM + MOETMAusing SPM MOETMA

Polyvinylidene fluoride - PVDF Ultrafiltration membranes Hydrophobic polymer

K S OK2S2O8K2S2O5PVDF

PVDF-coated graft co-polymer

Graft Copolymerization On PVDF-coated surface using SPM + MOETMAusing SPM MOETMA

Polyvinylidene fluoride - PVDF Ultrafiltration membranes Hydrophobic polymer

1) Surface characterization of the grafted PVDF surface

2) Antibiofouling properties and involved mechanisms

K2S2O8K S OPVDF K2S2O5PVDF

PVDF-coated graft co-polymer

ATR-FTIR and water drop contact angle of PVDF-surface grafted with MOETMA and SPMsurface grafted with MOETMA and SPM

62 º ± 3 º

90º ± 4º

Structural, viscoelastic properties and mass changes in real-time using quartz crystalchanges in real time using quartz crystal

microbalance with dissipation technology (QCM D)dissipation technology (QCM-D)

.

Real-time monitoring of graft polymerization on PVDF using quartz crystal microbalance with dissipation

DDW Monomers

0z

Monomers

-100

Shi

ft, H

Monomers+

-200

ency

S Initiators

Washing stages

-300Freq

ue

g g

0 50 100 150Ti Mi tTime, Minutes

Characterizing swelling with QCM-D

2

100 mM NaCl

DDWDDW 100 mM NaCl

0

1

Fact

orEPS

-2

-1

0

issi

patio

n Cl -

0 20 40 60 80-3

2

Time, Minutes

Di

8

Unmodified PVDF

ONa+

0

1

2

Fact

or

4

6

8

Shift

, Hz Graft polymerized PVDF

PVDF-coated Graft co-polymers

-2

-1

0

Dis

sipa

tion

F

0

2

Freq

uecy

S

0 20 40 60 80-3

T im e, M inutes

D

-2

F

Characterizing swelling with atomic force microscopy

Modified Surface in DDW Modified Surface in NaCl

How swelling affects force interactions ith d l f l t?with model foulant?

30

20

30Unmodified crystal in 100 mM NaCl

Modified crystal in 100 mM NaCl

10

mN

/m) Unmodified crystal in DDW

Modified Crystal in DDWEPS

10

00 0.1 0.2 0.3 0.4 0.5

adiu

s (m

CC

O

O

CH3 O

EPS

Cl -

-20

-10

orce

/Ra3

CC

C

O

O

CH3 Na+

-30Separation Distance (µm)

Fo

PVDF-coated Graft co-polymers

-40Separation Distance (µm)

Force interactions with model foulant

100

100 Modified, DDWNon-modified, DDW

60

80

Avg: 29.9 mN/mStd: 3.74 mN/m

ency

, % 60

80 Avg: 3.5 mN/mStd: 2.38 mN/m

ency

, %

0

20

40

Freq

ue

0

20

40

Freq

ue

0 5 10 15 20 25 30 35 400

Force/Radius, mN/m0 5 10 15 20 25 30 35 40

0

Force/Radius, mN/m

100 100 Modified NaClNon-modified, NaCl

60

80

100


y, % 60

80

100


y, %

Modified, NaClNon modified, NaCl

20

40

Freq

uenc

y

20

40

Freq

uenc

y

0 5 10 15 20 25 30 35 400

Force/Radius, mN/m0 5 10 15 20 25 30 35 40

0

Force/Radius, mN/m

The source of foulant:Extracellular Polymeric Substances (EPS) fromExtracellular Polymeric Substances (EPS) from

MBR system

Carriers

EPS Page 22

EPS Extraction MethodEPS extraction is carried out by formaldehyde- NaOH method:

Formaldehyd NaOH10 mL sample + 0.06 mL formaldehyde(37 %), 1 h, 4 °

Formaldehyde

NaOH

sample + 4 mL 1 N NaOH, 3 h, 4°C

centrifugation 3500rpm 30 min

filtration the supernatant with Nylon membrane Filter (0.45um 47mm)

centrifugation 3500rpm, 30 min

dialysis against deionized water overnight

freeze-drying(−80°C for 48 hours)

Di l i L hili tiDialysisFiltration

Lyophilization

Effect of surface modification on adhesion of EPS

Time, MinutesTime, Minutes

20 20 40 60 80 100 120

A2

0 20 40 60 80 100 120

ADDW

2

0

ft, H

z

A BDC E

2

0

ft, H

z

A BDC E

DDW NaCl

DDWNaClEPS

-4

-2

ncy

Shif

-4

-2

ncy

Shif

8

-6

Freq

uen

Modified Crystal8

-6

Freq

uen

Modified Crystal

-10

-8 Non-Modified Crystal

-10

-8 Non-Modified Crystal

ATR FTIR t fNon-modified

ATR-FTIR spectrum of

fouled QCM-D sensors

with EPS

Modified

Concluding Remarks

• We successfully co-grafted MOETMA and SPM on y gpolyamide and PVDF surfaces.

• Copolymer grafted layer possessing oppositely chargedCopolymer grafted layer possessing oppositely charged groups is reducing fouling due to increased hydrophilicity and swelling.

• The significant reduced adsorption of MBR-originated EPS to modified PVDF surface has strong anti-biofouling g gimplications.

Acknowledgments

• Sophia Belfer• Roza Feinstein• Slava Freger• Gideon Oron• Gideon Oron

• Amer Sweity• Matan Brami• Yair Kaufman

• Funding: BMBF 2010

Thanks for the attention!Thanks for the attention!

Moshe Herzberg - ilmar.org.il · SPM Sulfopropyl methacrylate MOETMA Methacryloyloxy ethyl trimethylammonium Polymer surface Co-graft-polymerization. MOETMA + SPM modification K 2S

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