SULFOSUCCINIC ACID:AN EFFICIENT CROSSLINKING INTERMEDIATE FOR

COSMETIC HYDROGELS

Martin Häubl (ESIM Chemicals GmbH)

C. Pretschuh, M. Steiner. M. Mihalic (Wood K Plus, Linz, Austria)

Chemspec 2018

ESIM CHEMICALS AT A GLANCE

2ESIM Chemicals

ESIM Chemicals is a global leader in custom development and production of fine chemicals for various industries and a flexible supplier of maleic anhydride, fumaric acid, maleates, succinates and fumarates.

520Employees

75+Years of Expertise

200MEUR Net Sales

2Business Clusters

CHEMISTRY PARK LINZ AT A GLANCE

3ESIM Chemicals

Linz is the home of a well established and globally active chemical industry. >40

Companies

3,500Employees

1.2 km2

Area

31 km

Railway net

2,500MEUR

Replacement Value

300MEUR

Infrastructure

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MARKETS WE FOCUS ON

Crop Protection Polymers

Pharma Food Feed

Electronics CosmeticsPersonal Care

BUSINESS CLUSTERS

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Exclusive Synthesis Intermediates

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EXCLUSIVE SYNTHESISCORE TECHNOLOGIES OF ESIM INCLUDE:

ContinuousProcessing

Hydrogenation

Melt and Liquid Handling

Advanced Catalysis

Esterification

Distillation Solid MaterialHandling

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A HUGE VARIETY OF PLATFORM CHEMICALS AND SPECIALTIES

HIGH QUALITY STANDARDS

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WHEN HAVE YOU USED A HYDROGEL FOR THE LAST TIME?

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Ref. to: http://wienerin.at/home/leben/gesundheit/5217921/

Ref. to: https://www.ratgeber-hautgesundheit.de/pflege/kosmetik/

WHAT IS A HYDROGEL?

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Crosslinker

Hydrogel (swollen network)Dry solid (collapsed)

Polymer Chain

Water

MAJOR APPLICATIONS FOR HYDROGELS / MARKET PERSPECTIVE

� Cosmetic products

� Soft contact lenses

� Hygiene products (Superabsorbent fillers in diapers)

� Wound dressings

� Tissue engineering scaffolds

� Drug delivery

� Agriculture (water conservation)

� Food products

� Strong future market growth (CAGR 8%) in all applications

ESIM Chemicals 11

Ref. to: https://www.theeyegalleryok.com/

Ref. to: http://www.marineagar.net/

Ref. to: https://www.alibaba.com/

WHY ARE HYDROGELS WIDELY USED IN COSMETICS?

� To improve sensory properties of a lotion or cream

� Thickening agent

� Control release of active ingredients

� Bio-compatibility

� High water content

� Elasticity and softness

� Naturally sources (protein chains, polysaccharides)

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Ref. to: https://www.dreamstime.com/

Ref. to: https://www.nationalgeographic.org/

Ref. to: https://receptranaturals.com/

HOW TO IMPROVE HYDROGELS?

� Polymer

� Make use of naturally derived and sustainable materials (Polysaccharides, etc.) to substitute crude oil based polyacrylates

� Crosslinker

� Use a highly efficient crosslinker which leads to high performance hydrogels (swelling, rheological behavior)

� Substitute crosslinkers like epichlorohydrin, divinylsulfone, and various anhydrides by harmless materials, which are not cancerogenic to reduce toxic residues within the hydrogel

� Use of crosslinkers, which are readily biodegradable

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NATURALLY DERIVED POLYMERS:CELLULOSIC DERIVATIVES

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� Carboxymethylcellulose Sodium (CMCNa)

� Low cost naturally derived polysaccharide

� Biocompatible and biodegradable

� High molecular weights and low degree of substitution increases

crosslinking ratio [1],[2]

� Hydroxyethylcellulose (HEC)

� Biocompatible and biodegradable

� Spacer material to improve swelling of crosslinked hydrogels

� As it is less sterically hindered than CMCNa crosslinking is

promoted using this material [2]

[1] Ref. to: J. Appl. Polym. Sci. 110, 2453-2460, 2008[2] Ref. to: Carbohydrate Polymers 137, 2016, 59-64

SULFOSUCCINIC ACID AS CROSSLINKER:BIODEGRADABLE AND NON-TOXIC

� Sulfosuccinic esters are already well-known in the cosmetic ingredient sector (e.g. DOSS)

� Excellent biodegradability

� Excellent thermal crosslinker for hydrophilic naturally derived polymers (e.g. polysaccharides)

� Multifunctional: Crosslinking agent as well as esterification catalyst

� The insertion of a sulfonic acid group to the polymer network improves its hydrophilicity which leads to better swelling performance

� Non-cancerogenic (in contrast to epichlorohydrin etc.)

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O

O

OH

OH

S

O

HOO

RAW MATERIALS FOR GEL PREPARATION

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� Polymers:� Carboxymethylcellulose Sodium (CMCNa)

� Degree of substitution: 0.9� Mw: ~ 250.000� Na+: 8 wt%

� Hydroxyethylcellulose (HEC)� Degree of substitution: 0.4� Mw: ~ 90.000

� Crosslinker:� Sulfosuccinic Acid 99 %

� Diluted to a 7 wt% aqueous solution

PRINCIPLE OF CHEMICAL CROSSLINKING

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Ref. to: N. Reddy, R. Reddy, Qiuran Jiang, Trends in Biotechnology 33,6, p 362 – 369, 2015

CROSSLINKING REACTION USING SULFOSUCCINIC ACID

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Crosslinking of HEC and CMCNa with Sulfosuccinic Acid

O

O

OH

OH

S

O

HOO

x H2O

O

O

S

O

OHO

OO

RO

OR

O

OR

RO

RO

RO

O O R

n

O

OO

R'O

O

O

OR'

R'O

R'O

R'O

R'O O R'

m

∆

SWELLING RATIOS OF CMCNa-HECHYDROGELS

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67

128

117

0

20

40

60

80

100

120

140

2 4 6

Sw

ellin

g R

ati

o S

R [

%]

Reaction time [hours]

CMCNa/HEC 3:1 gels crosslinked with

10 wt% Sulfosuccinic Acid (SSA) at different reaction times

Reaction: 60°C, Curing: 2 hours at 80°C

VISCOSITY INCREASE DUE TO HIGHER CROSSLINKING RATIO

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1

10

100

1000

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0,01 0,1 1 10 100

Vis

cosit

y|

η*| [

Pa

s]

Angular Frequency w [rad/s]

0 % SSA 0.5% SSA 4% SSA 10% SSA

CMCNa/HEC gels crosslinked with different amounts of Sulfosuccinic Acid (SSA),Reaction: 4 hours at 60°C, Curing: 2 hour at 80°C

CMCNa/HEC 3:1 with 3 % solid content, parallel-plate-rheometer, 30°C, 1 – 10 % deformation

PREPARATION OF CELLULOSE BASED HYDROGEL USING SULFOSUCCINIC ACID

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OPTIMIZED REACTION PARAMETERS

� 3:1 mixture of CMCNa/HEC in water (1.5 wt% total solid content)

� Addition of Sulfosuccinic Acid as 7 wt% aqueous solution at 60°C (10 wt% based on total amount of cellulosic derivatives)

� Stirring of the reaction mixture at 60°C or 4 hours

� Final curing and drying at 80°C for 2 hours

� Swelling of the dried hydrogel in water to obtain a hydrogel with 5 wt% solid content

1

10

100

1000

10000

0,01 0,1 1 10 100

Vis

cosit

y|

η∗| [

Pa

s]

Angular Frequency ω [rad/s]

CMCNa/HEC 3:1 gel crosslinked with 10 wt% Sulfosuccinic Acid (SSA), Reaction: 4 hours at 60 °C; Curing: 2 hours at 80°C

CMCNa/HEC 3:1 with 5 % solid content, parallel-plate-rheometer, 30°C, 1 – 10 % deformation

VISCOSITY OF THE HYDROGEL AT OPTIMIZED REACTION CONDITIONS

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COMPARISON WITH CARBOPOLS: VISCOSITY

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0

1

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100

1.000

10.000

100.000

0,01 0,1 1 10 100

Vis

cosit

y |

η∗| [

Pa s

]

Angular Frequency ω [rad/s]

Parallel-plate-rheometer, 30°C, 1 – 10 % deformation

Carbopol 980 3 wt% Carbopol 981 3 wt% CMCNa - HEC opt 5 wt%

0

1

10

100

1.000

10.000

100.000

1 10 100

Defo

rm

ati

on

γ [

%]

Shear Stress τ [Pa]

Parallel-plate-rheometer, 30°C

Carbopol 980 3 wt% Carbopol 981 3 wt% CMCNa - HEC opt 5 wt%

COMPARISON WITH CARBOPOLS: REVERSIBLE ELASTIC LIMIT

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REM PICTURES OR FREEZE DRIEDHYDROGELS

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Carbopol 980 (3 wt%)CMCNa – HEC Gel opt (5 wt%)

CONCLUSIONS

� Successful crosslinking of a biodegradable hydrogel without toxic residues based on cellulose derivatives (CMCNa and HEC) using Sulfosuccinic Acid.

� Optimal crosslinking parameters were reached at a Sulfosuccinic Acid level of 10 wt%, and crosslinking temperatures of 60°C for 4 hours followed be a further curing step at 80°C for 2 hours. The obtained hydrogel showed similar properties to commercially available Carbopol(Polyacrylic Acid) gels.

� A 5 wt% aqueous crosslinked cellulosic CMCNa-HEC Hydrogel showed a rheological behavior similar to a 3 wt% aqueous Carbopol gel.

� If the amount of Sulfosuccinic Acid exceeds 10 wt% the increased crosslinking ratio results in a poor swelling behavior of the gel (limited water accessibility to the polymer network).

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ACKNOWLEDGEMENT

This study was performed together with the Competence Centre for Wood and Wood-related renewable resources (Wood K plus) and co-financed by the Austrian Research Agency FFG.

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CONNECT WITH US @ BOOTH F10

Dr. Martin Häubl

ESIM Chemicals GmbH

St.-Peter-Strasse 25

4020 Linz

Austria

Tel: +43 732 6982-2483

Mobile: +43 664 88236163

martin.haeubl@esim-chemicals.com

www.esim-chemicals.com

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