SYNTHESISE AND CHARACTERIZATION OF STARCH SILVER

NANOCOMPOSITE FILMS

Nur Fatin Nadiah Binti Jamil

Bachelor of Science with Honours

(Program of Resource Chemistry)

2013

1

SYNTHESISE AND CHARACTERIZATION OF STARCH SILVER NANOCOMPOSITE

FILMS

NUR FATIN NADIAH BT JAMIL

Resource Chemistry

Faculty of Resource Science and Technology

University Malaysia Sarawak

ABSTRACT

Starch has been widely used as a raw material in films production due to its low cost and

biodegradable properties. In this project, silver nanoparticles will be added to starch solution

to form Nano composites films with anti-microbial properties. Parameters such ratio of starch

and silver nanoparticles used together with amount of cross-linkers were investigated and

optimized to produce starch-silver Nanocomposite films with desirable physical and

anti-microbial properties. FTIR, SEM, FEM and UV-Visible spectrophotometer were used to

characterized morphology, particle size and changes in chemical composition of starch-silver

nanocomposite films.

Keywords : Nanoparticles, anti-microbial, nano-composite films

ABSTRAK

Kanji telah digunakan secara meluas sebagai bahan mentah dalam pengeluaran filem kerana

kos yang rendah dan sifat-sifat mesra alam. Dalam projek ini, nanopartikel argentum akan

ditambah kepada penyelesaian kanji untuk membentuk nanokomposit filem dengan ciri-ciri

anti-mikrobial. Parameter nisbah seperti kanji dan argentum nanopartikel digunakan

bersama-sama dengan jumlah silang linkers akan disiasat dan dioptimumkan untuk

menghasilkan filem-filem kanji komposit nano perak dengan sifat-sifat fizikal dan anti-mikrob

wajar. FTIR, SEM, FEM dan spektrofotometer UV-nyata akan digunakan untuk ciri-ciri

morfologi, saiz zarah dan perubahan dalam komposisi kimia filem Komposit nano kanji perak.

Keywords: nanopartikel, anti-mikrob, filem nano-komposit

2

1.0 Introduction

Due to increase number of waste generated from plastic in the world, researcher started to find

alternative ways of replacing plastics. In recent years, degradable films have attracted wide

spread interest due to increasing environmental pollutants. Degradation of conventional plastic

requires years to fully biodegrade, which leads to secondary pollutants and costly. Thus,

environmental friendly biodegradable film has been developed.

Among many natural biopolymers to prepare a biodegradable films, starch is one of the most

commonly used as raw materials due to its abundance, low cost, renewability and

biodegradability (Avenous et al., 2001). However, the application of starch films was limited

because of its own weakness such as water solubility and brittleness (Mathew et al., 2006). In

order to overcome the shortcomings and get functional properties, starch is often combined

with other natural biopolymer to form composite films.

Starch is a polymer which occurs widely in plants. Starch consists of replicating units of

glucose. Starch contains 30% of amylase and 70% amylopectin and less than 1% lipids and

proteins from plants is a fine addictive for forming membrane owing to its insoluble properties

(Fujun et al., 2009). In its application in biodegradable plastic, starch is physically mixed in

with its active granules, kept intact, or melted and blended on a molecular level with the

appropriate polymer.

The fraction of starch in mixture which is accessible to enzymes can be degraded by either, or

both amylases and glycosidase. Term sago is used to describe starch from the stem of palms,

cycads and from maniac tubers. Sago palm contains a large amount of starch in its trunk and

3

its productivity was calculated to be four times that of paddy rice (Ishizuka et al., 1995). Sago

starch produced from pith of sago palm, is a useful resource for commercial raw materials and

food stuff also important product in South Asia ( Yatsugi et al., 1986).

According to Takashi (1998), the properties of sago starch can be easily gelatinized, as it

gelatinization occurs at low temperature, it easily to mould and gel syneresis is also low and

highly viscous. Previously, due to the good film-forming property, excellent biocompatibility

and certain antimicrobial activity (Park at el., 2004 ; Xiao et al., 2010) chitosan has often been

chosen as raw material to prepare the composite films.

Recently, silver nanoparticles exhibiting antimicrobial activity have been synthesised (Zhu et

al., 2006). Antibacterial activity of the silver-containing materials can be used, for example, in

medicine to reduce infections as well as to prevent bacteria colonization on dental materials,

stainless steel materials, and human skins (Maillard et al., 2002 ; Mock et al., 2002). Due to its

high reactivity as large surface to volume ratio, nanoparticles play crucial role inhibiting

bacterial growth in aqueous and solid media. Silver-nanoparticles containing materials can be

employed to eliminate microorganisms on textile (Zhu J.J et al., 2001) or use for water

treatment (Mock J.J et al., 2002).

In this study, starch-silver nanocomposite films were prepared by incorporation of silver

nanoparticles into starch films. The physical and antimicrobial properties of the starch-silver

nanocomposite were tailored by varying the composition of the films.

4

1.1 Objectives

The objectives of this research project are:

1. To synthesize starch-silver nanocomposite films

2. To characterize the physical and antimicrobial properties of the starch-silver

nanocomposite films.

5

2.0 Literature Review

2.1 Starch as raw material

In its application in biodegradable plastics, starch is physically mixed in with native granules,

kept intact, or melted and blended on a molecular level with the appropriate polymer. Starch

molecules has two important functional groups, the -OH groups that susceptible to substitution

reactions and C-O-C bond that is susceptible to chain breakage. The hydroxyl group of

glucose has a nucleophile character. By reaction of its -OH group, modification of various

properties can be obtained. Cross-linking or bridging of the -OH groups changes the structure

into a network while increasing the viscosity, reducing water retention and increasing its

resistance to thermo mechanical shear. Starch films possess low permeability and thus

attractive materials for food packaging.

However, due to it’s the strong intermolecular and intramolecular hydrogen bond in starch,

native starch is not a true thermoplastics. In presence of plasticizer, for example, water and

glycerol, at high temperature. Among the plasticizer, water is most commonly used in thermal

processing of starch based polymer. Bio-plastic starch containing only water alone, possess

poor mechanical properties such as brittleness due to the fast retro degradation

(recrystallization). Thus, other non-volatile plasticizer is investigated to improve the

processing ability and product properties of bio-plastic starch such as glycerol, glycol, sugar,

urea and citric acid.

Besides, the chemical used for cross-linking starch a relatively toxic, expensive or do not

provide the desired improvement in properties. Blending synthetic polymers with starch at

high temperature could damage starch and lead to poor properties of the material developed.

6

2.2 Citric acid cross-linking starch films

Poly(carboxylic acid), such as citric acid, is inexpensive and non-toxic chemicals that had

been used to improve the performance properties of cellulose and proteins in textile

applications (Yang C. et al., 1991 ; Yang C. et al., 1997 ; Yang Y. et al., 1996). Cotton and silk

fabrics have been cross-linked with carboxylic acid, mainly improve their appearance and

resistance to wrinkling, and also shown that the mechanical properties and water stability of

regenerated protein fibers can be improved by cross-linking with poly(carboxylic acid) (Yang

Y. et al., 1996). Carboxylic acid cross-link the hydroxyl group of cellulose and the

cross-linking reaction is reported occurring at temperature between 165oC to 175oC (Yang Y.

et al., 1996 ; Yang C. et al., 1997).

Scheme 1: Mechanism of conventional dry cross-linking of cellulose using carboxylic acid

with presence of catalyst, R represents cellulose (Yang and Wang 1996 et al., 1997)

Cross-linking poly(carboxylic acid) of cellulose occurs mainly through the hydroxyl group.

Since starch also contains considerable amount of hydroxyl group and starch is more easy

accessible to chemical than cellulose (refer Sheme1), poly(carboxylic acid) can be expected to

cross-linking starch and improve its properties (Narendra et al., 2010). Citric acid has not been

7

used to cross-link starch widely, it has been reported that citric acid can form strong hydrogen

bond interaction with starch improves its thermal and water stability and inhibit

retrodegradation ( Yu J. et al., 2005).

Incorporating citric acid substantially reduce the tensile stress of the products developed under

the condition (Yu J. et al., 2005). Citric acid was also used as additive to starch-PVA films, due

to the improvement in tensile strength and concentration above 5% reduce the tensile strength

of films. At high concentrations, there is excess cross-linking that limits the mobility of starch

molecules, leading to lower tensile strength (Yang Y. et al., 1996 ; Yang C. et al., 1997).

2.3 Silver nanoparticles

Silver nanoparticles are of interest due to its unique properties, such its size and shape which

can be incorporated into antimicrobial applications. Several physical and chemical methods

have been used for synthesizing and stabilizing silver nanoparticles (Senapati et al., 2005 ;

Klaus-Joerger et al., 2001). The most popular chemical approaches, including chemical

reduction using variety of organic and inorganic reducing agents, electrochemical techniques,

physicochemical reduction, and radiolysis are widely used for the synthesis of nanoparticles.

2.3.1 Synthesis of silver nanoparticles

The most common approach for synthesis of silver nanoparticles is by chemical reduction

using organic or inorganic reducing agents. Generally, different reducing agents such, sodium

citrate, sodium borohydride NaBH4, polyol process and Tollen reagent are used for reduction

of silver ions (Ag+) and lead to formation of metallic silver (Ag0) which followed by

agglomeration into oligomeric cluster. These cluster can eventually formed a metallic colloidal

8

silver particles (Wiley et al., 2005 ; Evanoff and Chumanov 2004 ; Merga et al., 2007). Thus,

it is important to use protective agents to stabilize dispersive nanoparticles during the course

of metal nanoparticles preparation, and protect the nanoparticles that can be absorbed on or

bind onto nanoparticles surfaces, avoiding their agglomeration (Oliveira et al., 2005).

Silver nanoparticles were prepared using water as an environmentally-friendly solvent and

polysaccharides as capping/reducing agents. The synthesis of satrch-silver nanoparticles was

carried out with starch (as a capping agent) and ß-D-glucose (as reducing agent) in a gently

heated system (Raveendran et al., 2003). The binding interactions between starch and

produced silver nanoparticles were weak and could be reversible at higher temperatures,

allowing for the separations of the synthesized nanoparticles. Besides, silver nanoparticles

were synthesized by the reduction of silver ions inside nanoscopic starch templates

(Raveendran et al., 2003, 2005). Extensive network of hydrogen bands in templates provided

surface passivation or protection against nanoparticles aggregation.

Smaller silver nanoparticles were synthesized by mixing two solutions of silver nitrate

containing starch (as a capping agent), and NaOH solutions containing glucose (as reducing

agent) in spinning disk reactor witha reaction less than 10 mins (Tai et al. 2008). Silver

nanoparticles with controllable size were synthesized by reduction of [Ag(NH3)2]+ with

glucose, galactose, maltose and lactose (Panacek et al., 2006). In addition, conventional

heating approach (simultaneously polymerization-reduction method) to polymerize

acrylonitriles reduces silver ions resulting in homogeneous dispersal and narrow size

distribution of the silver nanoparticles in silver-polyacrylonitrile composite powders (Zhang et

al., 2003).

9

2.3.1.2 Applications of silver nanoparticles

Nanoparticles exhibit size and shape-dependent properties which are of interest for

applications ranging from bio-sensing and catalyst to optics ,antimicrobial activity and

wireless electronic logic. These particles also have many applications in different fields such

as medical imaging, nano-composite, filters, drug delivery and hyperthermia of tumors (Tan et

al., 2006 ; Lee et al., 2008 ; Pissuwan et al., 2006).

Silver nanoparticles have been used extensively as antimicrobial agents in health industry,

food storage, textile coatings and a number of environmental applications. It is shown that

silver nanoparticles mainly in range of 1-10nm attached to the surface of Escherichia coli.

(E.coli) cell membrane, and disturbed its proper function such as respiration and permeability

(Morones et al., 2005). Introduction of nano-sized silver into poly(vinyl alcohol) provides

antibacterial activity, which highly desired in textiles used in medicine, wound dressing

applications, clothing and household products (Hong et al., 2006).

These silver/TiO2 composite films were prepared by incorporating silver in the pores of

titanium dioxide films with an impregnation method via photoreduction (a versatile and

convenient process with advantage of space-selective fabrication). It was reported that these

composite films are promising in application of antimicrobial and self-clean technologies (Liu

et al., 2008).

10

3.0 Materials and Methods

3.1 Materials

Sago starch (OPAC brand) was used in this study. Citric acid monohydrate (CA), sodium

hydroxide (NaOH), silver nitrate (AgNO3), ß-D-glucose. Ultra-pure water was used

throughout the experiment (Water Purifying System, Ultra Genetic, and Model : ELGA,UK ).

3.2 Methods

3.2.1 Preparation of Citric Acid Cross-linked Starch

The reactions were carried out between the esterification reaction of sago starch and citric acid

monohydrate. Sago starch was added into the water to form a gelatinized starch solution, and

stirred at temperature of 75oC, NaOH solution was added as a catalyst. The mixture was

heated for 15 minutes followed with addition of citric acid. The heating was continued for 40

minutes.

11

Figure 1 : Flow diagram on preparation of Starch Citrate films

3.2.2 Synthesis of Starch citrate with Silver Nanoparticles.

Starch citrate with silver nanoparticles can be obtained by addition of AgNO3 and glucose to

starch citrate solution and stirred for 15 minutes at temperature of 55-750C. Then addition of

NaOH drop by drop with vigorous stirring till colorless solution turns to reddish brown.

Sago starch + ultra-pure water

Gelatinized starch solution

Addition of 0.3mL of 4M NaOH. Heated at temperature of 75oC for 15 minutes under

magnetic stirring

Citric acid modified starch

Addition of quantitative amount of citric acid

Heated at 55oC for 40 mins

Parameters of preparation of Citrate Starch : Reaction time Amount of acids

Starch Citrate solution

Starch citrate film

12

Figure 2 : Flow diagram on synthesis of AgNPs doped in starch citrate solution

3.2.3 Samples Characterizations

Fourier Transform Infrared Spectroscopy (FT-IR) was used to examine functional group of

modified starch. Starch-silver nanocomposite films were sent for Scanning Electron

Microscope (SEM) to observe its surface morphology and morphology of nanoparticles.

UV-visible Spectrophotometer was used to confirm the formation of silver nanoparticles.

3.2.3.1 FT-IR

Prior to the characterization, the modified starch film was washed with ultra-pure water to

remove unbound citric acid monohydrate and a film was dried. The thin films was cut into

smaller pieces and grind with dried KBr pellet by ratio 1:100. Then, the pellet was scanned

Temperature of solution maintain at 75oC and

vigorously stirred Addition of 1ml glucose

solution and 1ml of AgNO3 (0.001M).

Addition of NaOH (4M), drop by drop and solution

were vigorously stirred

Casted in the petri dish, 25ml each, and dried in oven at temperature of 50oC for 24

hours.

Starch Citrate solution (colourless solution)

Solution turns from colourless to dark yellowish

brown

13

through FT-IR at the wave number in the range between 400-4000 cm-1.

3.2.3.2 SEM

A starch-silver sample solution was dropped on stainless steel plate and dried in oven. The

samples were coated with plantinum to avoid charges during characterization. To observe the

size distribution of nanoparticles surface morphology were characterized with SEM.

3.2.3.3 UV-Visible Spectrophotometer

The starch-silver solution was isolated and placed in a small glass bottle and wrapped with

aluminum foiled. Ultra pure water in a blank cuvette was run as a baseline, and followed with

ultra pure water with a drop of starch-silver and run as sample. Samples were scanned at range

of 200-700 nm.

3.2.3.4 Swelling degree

The swelling degree of the samples was characterized at 37oC, for which samples with 1 cm

diameter were placed in deionized water. The experiments were carried out by measuring the

weight gain as a function of immersion time in 20 ml water. The swelling degree was

calculated by using the following equation,

Swelling degree: Wt –Wo

Where, Wt is the wet weight of the samples, Wo is the original dry weight of the sample.

X 100 Wo

14

3.2.3.5 Zone of inhibition

Zone inhibition test was performed in Lysogeny broth (LB) agar plates with starch citrate

AgNPs films. 25ml of LB agar was poured in autoclaved petri plates, and 1.0ml of active

bacterial culture was homogeneously spread in agar plates and starch films were placed in the

agar. Method adapted from standard protocol based on National Committee for Clinical

Laboratory Standards (NCCLS) recommendation. The plates were incubated at 37oC for 24

hours. The zone size was observed.

15

4.0 RESULTS AND DISCUSSION

4.1.0 Preparation of Starch Citrate

There is an optimum amount citric acid that is necessary to obtain good increase in the tensile

strength of the films. Cross-linking interconnects the starch molecules in the film, which could

increase the molecular weight of the starch and also provides better inter-molecular interaction

between molecules, leading to better tensile strength ,compared to the non-cross-linked starch

films.

Curing time

(mins)

Amount of citric acid (wt./v)%

1.5

2.0

2.5

20

Transparent

Quite Brittle

Weak Strength

Transparent

Not Flexible

Poor Strength

Transparent

Flexible

Weak strength

30

Transparent

Flexible

Transparent

Flexible

Transparent

Flexible

16

Moderate Strength Weak Strength Weak Strength

40

Transparent

Flexible

Good strength

Transparent

Flexible

Weak Strength

Transparent

Flexible

Weak Strength

Table 1 : Effects of curing time and amount of citric acid to properties of modified films.

Table 2 : Synthesis parameters used in preparation and citric acid modified starch

At low amount of citric acid, there is not enough cross-linking between the starch molecules to

Sample

( starch to

citric acid)

Synthesis Parameters

Native sago Starch

(g)

Citric acid (g)

Sodium Hydroxide (4.0M) mL

Reaction time

( minutes )

Temperature ( oC )

SCA 1

(4:3) 2.0236 1.5033 0.3 40 55

SCA 2

(1:1) 2.0062 2.0031 0.3 40 55

SCA 3

(4:1) 2.0066 1.0041 0.3 40 55

SCA 4

(2:1) 2.0210 0.5011 0.3 40 55

17

improve the tensile strength of the films. At high amount of citric acid, there is excess

cross-linking that limits the mobility of starch molecules, leading to lower tensile strength

( Yang et al., 1996 ).

Further increase in reaction time substantially decreased the strength of the films. Reaction

time is one of the most important factor determining the efficiency of the carboxylic acid

cross-linking and hence the properties of the cross-linked materials. Suitable reaction time is

necessary for the cross-linking reaction to occur but excess reaction time will damage the

starch molecules, leading to decrease in tensile strength and unwanted changes in the color of

the films.

An optimum reaction time of about 5 minutes at about 167-170oC was reported for citric acid

cross-linking of cotton fabrics. In this research, temperature was adjusted to 550C and thus, the

reaction time was increase to 40 minutes. Longer reaction times were maybe suitable, if lower

temperatures were used, but shorter reaction time for large-scale processing of films, due to

economic and technical reasons.

42

0.7

8

66

8.6

083

9.8

9

92

5.2

1

10

25

.05

11

55

.19

14

22

.35

14

59

.25

15

14

.62

15

41

.24

16

49

.45

16

79

.18

17

40

.72

23

34

.95

23

62

.50

34

45

.47

*******SS

4

6

8

10

12

14

16

%T

52

6.5

85

75

.26

70

9.8

9

76

4.9

4

85

9.8

2

92

9.7

1

10

18

.08

10

82

.67

11

60

.27

13

70

.71

14

23

.48

16

41

.24

29

29

.64

34

48

.06

*pure s tarch

0

2

4

6

8

10

12

%T

500 1000 1500 2000 2500 3000 3500

Wav enumbers (cm-1)

Figure 3 : FTIR result for native sago starch

18

52

1.1

75

76

.73

76

0.1

9

85

3.3

19

33

.72

10

24

.64

10

79

.27

11

53

.52

12

31

.69

14

00

.29

15

12

.75

15

40

.74

15

59

.04

16

49

.79

17

33

.68

17

95

.26

29

37

.01

34

43

.31

*A

-20

0

20

40

%T

57

6.9

4

66

6.2

9

74

8.6

8

85

4.6

0

93

3.6

6

10

24

.17

10

79

.38

11

53

.24

12

29

.89

14

00

.68

15

60

.44

16

49

.12

17

32

.73

29

36

.02

34

18

.90

*B

-50

0

50

%T

57

7.4

2

75

9.8

8

85

6.9

8

93

4.3

6

10

25

.48

10

79

.18

11

52

.67

12

28

.98

13

98

.81

15

11

.21

16

45

.83

17

29

.23

29

23

.78

34

24

.68

**C

-50

0

50

%T

51

5.1

2

67

0.1

4

75

3.4

4

84

7.5

9

93

1.6

4

10

76

.81

12

34

.24

13

67

.12

13

96

.18

14

22

.09

14

58

.42

15

13

.94

16

48

.32

17

33

.19

29

30

.05

35

65

.83

*****D

40

60

80

100

%T

500 1000 1500 2000 2500 3000 3500

Wav enumbers (cm-1)

Figure 4 : FTIR spectrum for Starch Citrate (a) SCA1, (b) SCA2, (c) SCA3, (d) SCA4

The FTIR spectrum of native sago starch (Figure 4) showed broad absorption peak at 3448

cm-1 indicating presence of intermolecular hydrogen bonding hydroxyl group having

polymeric association. Peak expressed on 2929 cm-1 refers to C-H stretching and 1423 cm-1

indicates C-H bending as presence of hydrocarbon chromospheres in native sago starch.

Comparing with cross-linked sago starch with native sago starch, both films have similar

peaks, except additional peak in the cross-linked films at 1736 - 1741 cm-1.The band is

ascribed to carboxyl and ester carbonyl bands (Yang et al., 1991).

The presence of carbonyl group shows the reaction condition applied is feasible for

esterification of citric acid with sago starch. Since the films were thoroughly washed to

remove unreacted citric acid, the presence of carbonyl peak confirmed the chemical linkages

b

a

c

d

19

between citric acid monohydrate with starch. Based on the result obtained, ratio of 4:3

provides good properties of starch modified films and maintained in the next proceedings.

4.1.1`Effect on morphology of starch citrate films by varying amount of citric acid used

a) b)

c) d)

e)

Figure 5 : SEM images on surface of (a) Native starch films ,(b) SCA4 ,(c) SCA 3 , (d)

SCA2 , (e) SCA1

e

20

Scanning Electron microscope images of the control and cross-linked films does not show any

appreciable change in surface morphology due to the cross-linking as seen Figure 5. These

films are homogenous and have no cracks, it shows well dispersed starch molecules ( Garg &

Jana et al., 2007) but the surface are less smoother than native starch films.

4.2.0 Preparation Starch citrate with Silver nanoparticles

The formation of silver nanoparticles in this experiment is where silver nanoparticles were

prepared using water as an environmentally-friendly solvent and starch as capping/reducing

agents. In this experiment starch acts as capping agent and ß-D-glucose acts as the reducing

agents. This method were reported by (Raveendran et al., 2003) which it said that the synthesis

of starch-silver nanoparticles was carried out with starch (as a capping agent) and ß-D-glucose

(as reducing agent) in a gently heated system.

As the silver nanoparticles possess antimicrobial properties, thus, the effectiveness of the

antibacterial activities in different types of starch films was tested. Different types of starch

films was prepared which are, native starch with silver nanoparticles (SS), starch citrate doped

with silver nanoparticles (SCS) and starch citrate with AgNO3 (SCA). In order to ensure the

formation of silver nanoparticles, the starch solution with nanoparticles were tested using

UV-visible spectrophotometer.

21

4.2.1 Different Preparation Method Of Ag-NPs in starch citrate film

Figure 6 : Different method on preparation of Ag-NPs in sago starch solution.

The different between two method above are, in method A, the sago starch was being modified

before synthesize of Ag-NPs take place, compared with method B the pure sago starch

solution proceed with synthesize of Ag-NPs then only cross-linked process take placed.

Method A, the sago starch was cross-link with citric acid before AgNPs was synthesis. The

hydroxyl group in the starch helps in reduction of silver ions. Due to the modification, the

hydroxyl group is being converted to ester carbonyl. Thus, there is less availability of free

hydroxyl group to reduce the Ag + ions, addition of glucose aids the process of reduction.

Starch Solution

Starch citrate solution Synthesis of AgNPs in starch solution

Cross-link AgNPs starch solution with

citric acid

Synthesis AgNPs in-situ

Starch-citrate-AgNPs (SCS) Starch-AgNPs-citrate

(SSC)

A B

Films

22

84

5.3

4

91

5.9

6

10

23

.20

10

80

.02

11

54

.39

12

80

.79

13

94

.96

15

85

.58

16

54

.45

17

36

.83

29

40

.19

34

46

.07

**SC S

-20

0

20

40

%T

83

2.8

8

92

7.0

3

10

27

.95

10

82

.85

11

52

.75

12

94

.07

13

95

.79

14

57

.64

15

61

.05

16

49

.10

17

37

.82

29

19

.14

34

45

.20

****SS

0

20

40

60%

T

76

0.0

2

83

6.5

2

93

4.5

9

10

24

.64

10

80

.37

11

54

.77

12

30

.771

39

6.9

8

14

55

.71

16

49

.15

17

36

.83

29

25

.48

34

45

.89

***SSC

-10

0

10

20

30

%T

500 1000 1500 2000 2500 3000 3500

Wav enumbers (cm-1)

84

5.3

4

91

5.9

6

10

23

.20

10

80

.02

11

54

.39

12

80

.79

13

94

.96

15

85

.58

16

54

.45

17

36

.83

29

40

.19

34

46

.07

**SC S

-20

0

20

40

%T

83

2.8

8

92

7.0

3

10

27

.95

10

82

.85

11

52

.75

12

94

.07

13

95

.79

14

57

.64

15

61

.05

16

49

.10

17

37

.82

29

19

.14

34

45

.20

****SS

0

20

40

60%

T

76

0.0

2

83

6.5

2

93

4.5

9

10

24

.64

10

80

.37

11

54

.77

12

30

.771

39

6.9

8

14

55

.71

16

49

.15

17

36

.83

29

25

.48

34

45

.89

***SSC

-10

0

10

20

30

%T

500 1000 1500 2000 2500 3000 3500

Wav enumbers (cm-1)

52

6.5

85

75

.26

70

9.8

9

76

4.9

4

85

9.8

2

92

9.7

1

10

18

.08

10

82

.67

11

60

.27

13

70

.71

14

23

.48

16

41

.24

23

71

.63

29

29

.64

34

48

.06

*pure s tarch

0

2

4

6

8

10

12

%T

57

9.4

376

2.9

6

10

25

.19

10

80

.34

11

54

.20

12

29

.97

14

03

.93

16

33

.58

16

73

.34

17

25

.74

23

62

.65

29

29

.68

34

41

.15

*s tarch-c itric -s ilver nano

-1

0

1

2

3

4

5

6

%T

1000 1500 2000 2500 3000 3500 4000

Wav enumbers (cm-1)

Figure 7: FT-IR result on (a) SS film (b) SSC film (c) SCS film

Based on the result in Figure 7, method B shows that, the crosslinking with citric acid are not

preferable after addition of Ag-NPs, as peak on 1736 - 1741 cm-1 were not observed ,this is

more probably because the hydroxyl group presence in sago starch reduce the AgNO3 and thus

the availability of free hydroxyl group to be cross link is minimized. From this research, it

shows that, synthesis of Ag-NPs starch citrate solution is more preferable.

b

c

a

23

Figure 8: Comparison on native starch films and SCS films.

a)

b)

Pure starch

SCS