Starch thickening.pdf

Starch Based Thickening agents forPersonal Care Surfactant Systems

B. Volkert, A. Lehmann, A. Schrader, H. Nerenz

58th Starch Convention, Detmold, April 25 – 27

Index of contents

1. Requirements and objectives

2. Approach of resolution

2.1 Carboxymethylation of starch (CMS)

2.2 Hydrophobic modification of CMS

2.3 Variation of the surfactant system

3. Summary

• high viscosity by low application concentration• long-term stability over a pH-range ~4 – 9• electrolyte und surfactant compatibility• high transparency of the gel• simple workability (quick swelling and pH-adjustment)• biological degradation• cheap• toxicological harmlessness• satisfy appliance properties (e.g. no gluey feeling on the skin)

Profile of qualification of a modern thickening agent forsurfactant systems


Used surfactant systems

14% Surfactant 2% Chemical modified starch

OOC12

SO3Nan

n = 12-14

2.) Anionic Surfactant ! Sodiumlaurethsulfate (SLES)

" less kindness to the skin as APG

" easier to thicken

OHO

HOOH

OH

O

OHO

HOOH O

(CH2)n

m

m = 0-3; n = 12 - 16

1.) Nonionic surfactant ! Alkyl polyglucoside (APG)

" high kindness to the skin

" not easy to thicken

" synergistic effect with anionic surfactants


" Synthesis of a starch based thickener for personal surfactant systems

" high transparency

" formulations should obtain a customary viscosity (~ 6000 mPas)

Objectives for this project


1st Approach of resolution

Use of Carboxymethyl starch as thickening agent

2.1 Carboxymethylation of starch

O

OHO OOH

HOO

HO OOH

HOO

HO OOH

HO O

OHO OOH

OO

HO OOH

HOO

HO OO

HO

NaOH; i-PrOH; 40°C; 4.5h

CO2-Na+

CO2-Na+

Cl-CH2-COOH

1565

20685

2260

56808140

17870

0

5000

10000

15000

20000

25000

0.55 1.08 1.45

Degree of substitut ion

Shea

r vi

scos

ity

[mPa

s] a

t Sh

ear

rate

= 2

.55

s-1

0% Surfactant

14% APG

Shear viscosity of 2% CMS-solutions

" CMS obtain a thickening effect forAPG

" CMS with a DS~1 showsmaximum shear viscosity


86.582.0

67.0

5.02.56.5

0

20

40

60

80

100

0.55 1.08 1.45

Degree of substitut ion

Tran

spar

ency

[%

]

0% Surfactant

14% APG

" only solutions of CMS without APG are bright

" solutions of CMS with APG aremilky white with low transparency

Transparency of 2% CMS-solutions


2nd Approach of resolution

Use of hydrophobic carboxymethyl starch as thickening agent

2.2 Hydrophobic modification of Carboxymethyl starch

Hydrophobic substitution of carboxymethyl starch

Etherfication Esterfication

e.g. Reaction with1,2-EpoxyalkanesAlkyl halogenides

e.g. Reaction with Acid halogenides

2.2 Hydrophobic modification of carboxymethyl starch

Starch

Alkylation (hom.) Carboxymethylation (het.)

Carboxymethylation (het.) Alkylation (het.)

Hydrophobation: Reaction with 1,2-Epoxyalkanes

Hydrophilation: Reaction with Monochloroacetic acid

1. Hydrophobation 1. Hydrophiliation

2. Hydrophilation 2. Hydrophobation

Possibilities for synthesis


O

OHO OOH

HOO

HO OOH

HOO

HO OOH

HO O

OHO OOH

OO

HO OOH

HOO

HO OO

HO

140°C; 4h; 3bar

CH3

O

n

n = 5, 7, 9 Base

n

nCH3

H3C

HO

OH

2 Reaction channels

Bien et al. NaOH (0.5 eq); Na2SO4 (0.5 eq); Epoxyalkanes (1.2 eq)

Funke et al. KOH (0.8 eq); Epoxyoctane (1.0 eq)

Homogeneous Hydrophobation


Homogeneous Hydrophobation


C6 ! 2-Hydroxyhexyl starch DS = 0.8

C8 ! 2-Hydroxyoctyl starch DS = 0.7

C10 ! 2-Hydroxydecyl starch DS = 0.9

C12 ! 2-Hydroxydodecyl starch DS = 0.9

O

OHO OOH

HOO

HO OOH

HOO

HO OOH

HO O

OHO OOH

OO

HO OOH

HOO

HO OO

HO

140°C; 4h; 3bar

CH3

O

n

n = 5, 7, 9 Base

n

nCH3

H3C

HO

OH

"starch isn´t complete decomposed

" remaining starch chains can react with1,2-epoxyalkanes

103 104 105 106 107 1080,0

0,2

0,4

0,6

0,8

1,0

1,2

dW

/d(lo

g M

)

Molar mass [g/mol]

Mw [106g/mol] wms after reaction 6.4 waxy maize starch 54.0

Molar mass distribution of waxy maize starch


O

OHO OOH

OO

HO OOH

HOO

HO OO

HO

NaOH; i-PrOH; 40°C; 4h

CH3

O

OHO OOH

OO

O OOH

HOO

HO OO

O

CO2-Na+

+Na-O2C

H3C

HOn

H3C

HO

OH

CH3

OH

Cl-CH2-COOH

n

nn

1. Carboxymethylation of 2-Hydroxyoctylstarch with 1-3 eq MCE

2. Studies of these starch derivatives in surfactant system

3. Using the best results to synthesise C6, C10 and C12 hydrophobic starches

Heterogeneous Hydrophilation


75406910

6165

55 80 30 15

5055

0

2000

4000

6000

8000

C6-CMS C8-CMS C10-CMS C12-CMS

starch derivat ive

Shea

r vi

scos

ity

[mPa

s] a

t sh

ear

rate

= 2

.55

s-1

0 % Surfactant

14% APG

SD DS2-Hydroxyalkyl DSCarboxymethyl

C6-CMS 0.8 0.83

C8-CMS 0.7 0.92

C10-CMS 0.9 0.84

C12-CMS 0.9 0.65

(C6 = 2-Hydroxyhexyl-; C8 = 2-Hydroxyoctyl-;C10 = 2-Hydroxydecyl-; C12 = 2-Hydroxydodecyl)

Shear viscosity of 0.5% 2-Hydroxyalkylcarboxymethyl starch solutions


95 95 92

54

21

6068

74

0

20

40

60

80

100

C6-CMS C8-CMS C10-CMS C12-CMS

starch derivative

Tran

spar

ency

[%]

0 % Surfactant

14% APG

SD DS2-Hydroxyalkyl DSCarboxymethyl

C6-CMS 0.8 0.83

C8-CMS 0.7 0.92

C10-CMS 0.9 0.84

C12-CMS 0.9 0.65

(C6 = 2-Hydroxyhexyl-; C8 = 2-Hydroxyoctyl-;C10 = 2-Hydroxydecyl-; C12 = 2-Hydroxydodecyl)

Transparency of 0.5% 2-Hydroxyalkylcarboxymethyl starchsolutions


Analysis by static light scattering (SLS)

0 1x1010 2x1010 3x1010 4x1010 5x1010 6x1010 7x1010-19,0

-18,5

-18,0

-17,5

-17,0

ln(K

*c/R

(Θ))

q2

2-Hydroxyoctylcarboxymethyl starch Carboxymethyl starch Alkylpoly glucoside

Dilutuion 1:10


2-Hydroxyoctyl-CMS

DSCM = 0.9

DS2-HO = 0.7

Carboxymethyl starch

DSCM = 1.1

CMS C8/CMS C10/CMS C12/CMS


APG solutions with different hydrophobic modified CMS


3rd Approach of resolution

Use of surfactant mixture APG/SLES

8160

29710

2830

35900

5165

98

70

9195

65

0

5000

10000

15000

20000

25000

30000

35000

40000

2-HDOCMS14% APG 0% SLES





surfactant mixtures

Shea

r visc

osity

[m

Pas]

at

shea

r rat

e =

2.55

s-1

50

55

60

65

70

75

80

85

90

95

100

Tran

spar

ency

[%]

" by adding SLES viscosityand transparency of the formulations increase

" max. of viscosity and trans-parency by adding 3% SLES

" addition of >3 % SLES viscosity and transparencydecrease

Shear viscosity and transparency of different surfactantmixtures


1% 2-HDOCMS

14% Alkylpoly glucoside

1% 2-HDOCMS

14% Alkylpoly glucoside

1% SLES

η(γ=2.55 s-1) = 5165 mPas

T = 70 %

η(γ=2.55 s-1) = 8160 mPas

T = 91 %

Comparison of formulations with and withoutSLES


3. Summary

" selective aqueous surfactant systems can be stable thicken bymodified CMS (~0,5% concentration)

" viscosity and transparency can be controlled bv varying the DS hydrophobic-hydrophilic and addition of SLES

" in principle application as emulsifying agent for O/W-emulsionenspossible

Thanks to

" Dr. Waltraud Vorwerg for the GPC and SLS data

" Dr. Jürgen Kunze for recording the 13C-NMR data

" Inst. Dr. Schrader for the cooperation

" Agency for renewable resources for the financial support

Documents

Starch thickening.pdf