Radiation Processing of Natural and Synthetic Polymers for Potential Applications El-Sayed A. Hegazy Former Chairman, National Center for Radiation

Transcription

1 Radiation Processing of Natural and Synthetic Polymers for Potential Applications El-Sayed A. Hegazy Former Chairman, National Center for Radiation Research and Technology Atomic Energy Authority Cairo, Egypt

2 OBJECTIVE: To study the effect of ionizing radiations on the crosslinking and degradation of some natural polymers such as CMC-Na, chitosan and alginate. Super absorbant materials and nano gels were prepared by radiation copolymerization of natural and synthetic polymers for possible use in industrial, agricultural and biomedical applications. 2

3 25 20 Gel Content (%) CMC Concentration (%) Effect of different CMC concentrations in water on its gel content at 20 kgy using EB irradiation in air atmosphere. 3

4 %CMC-Na 40%CMC-Na 50%CMC-Na Gel Content (%) Irradiation Dose (kgy) 4 Gel content (%) of cross linked CMC-Na as a function of irradiation dose at 35 o C.

5 kGy. 30kGy. 40kGy Swelling Ratio (g/g) Time (min.) 5 Effect of applied irradiation dose on the swelling ratio of crosslinked CMC-Na in distilled water (50 wt%).

6 Chitosan Molecular Weight x Blank With 10% H 2 O 2 ( v / w ) With 20% H 2 O 2 ( v/ w) With 10% KPS ( w / w ) With 10% APS ( w / w ) Irradiation Dose ( kgy ) Effect of irradiation dose on the degradation of chitosan in the presence and absence of additives 6

7 Sod. Alginate Molecular Weight x Blank With 10% H 2 O 2 ( v / w ) With 20% H 2 O 2 ( v / w ) With 10% KPS ( w / w ) With 10% APS ( w / w ) Irradiation Dose ( kgy ) Effect of irradiation on the degradation of Na-alginate in the presence and absence of additives. 7

8 Use of Degraded Natural polymers in agriculture as a growth promoter Degraded Na-alginate and chitosan could be used as a growth promoter for plants in agriculture purposes. The growth and other responses of zea maze plant treated with irradiated Na-alginate or chitosan of different MWts were studied. The test field results showed that the treatment of the zea plant with irradiated Na-alginate at 120, 160, and 200 kgy in the presence of APS resulted in increasing the growth in plant. Meanwhile, the use of chitosan under the same conditions enhances the plant growth and productivity as well. The increase in plant performance by using degraded alginate or chitosan suggested its acceptable use in agriculture field as growth promoter. 8

9 0 20 kgy 40 kgy 80 kgy 120 kgy 160 kgy 200 kgy Contro l SA Treated by 10% APS The growth and other responses of zea maze plant treated with irradiated Na-alginate of different MWts in APS 9

10 10 Radiation Cross-linking of Natural Products/ PAAm For the Use as Super Adsorbent Hydrogels Super Adsorbent Hydrogels are used in various fields including bandages and wound dressing, controlled drug delivery, humiditycontrolled products, soil conditioners, controlled release of fertilizers, aqueous waste management and gelling agents, medical health care products..etc.

11 CMC-Na:PAAm 50:50 60:40 70:30 80:20 Gel Content (%) Irradiation Dose (kgy) 11 Gel content of crosslinked CMC-Na:PAAm as a function of irradiation dose extracted at 50 o C after 24hr.

12 Swelling Rate (g/g) CMC-Na/PAAm 50/50 60/40 70/30 80/20 0/ Time (min) Effect of polymer composition on the swelling ratio of crosslinked CMC-Na:PAAm hydrogel, Polym. conc. 30 wt%. Irrad. dose 10kGy 12

13 200 Swelling Ratio (g/g) with blowing agent without blowing agent Time(min.) 13 Swelling ratio of CMC-Na:PAAm hydrogels (50:50) in distilled water.polym.conc. 30 wt% Irrad. dose 10kGy in Am Carbonate.

14 14 Bean plant cultivated in soil after 9 weeks: (A) Untreated (control), (B) Treated with PAAm and (C) treated with PAAm/Na-alginate.

15 50 50:50 (CMC-Na:PAAm) commercial diapers Swelling Ratio (g/g) Time (min.) 15 Swelling ratio of CMC-Na/PAAm superabsorbent hydrogel and commercial diaper in simulated urine solution.

16 Application of PNIPAAm grafted with some natural polymers 16 Effect of natural polymer on the release of ketoprofen from its corresponding copolymer with PNIPAAm at ph 1 and 7.

17 Radiation synthesis of nanosized hydrogel particles based on the interpolymer complexation between polyvinylpyrrolidone and polyacrylic acid by gamma radiation

18 DLS Results of irradiated (40 kgy) PVP/PAAC D av =280 nm PDI=0.176 (a) ph 4 Synthesis of PVP/PAAc nanogels by gamma irradiation in air atmosphere: (b) ph 7 D av =200 nm PDI=0.165 Volume-weighted Gaussian distribution analysis for irradiated (40 kgy) PVP/PAAC at ph 4 and 7. Feed composition: PVP/PAAc (35/65 mol/mol %); total conc. 0.5%; PVP

19 Multimodal distribution for the particles obtained from PVP/ PAAc polymers Figure (3) AFM image for PVP and PAAc polymers

20 DLS results for PVP/AAc aqueous solution at ph 4 D av =83 nm PDI=0.041 DLS results for system (B): PVP/AAc in deionized water at ph 4. PVP/AAc: 35/65 mol/mol %; Total conc.: 1.5%; PVP Mw = ; 20 kgy.

21 DLS results for N-VP/PAAc aqueous solution at ph 4 D av =57 nm PDI=0.086 DLS results for system (C): N-VP/PAAc in deionized water at ph 4. N-VP/PAAc: 35/65 mol/mol %; Total conc.: 1.5%; PAAc Mw = ; 20 kgy.

22 AFM image (topography and three dimensional) of PVP/PAAc nanogel particles investigated in deionized water.

23 Possible Bio-medical Applications of PVP/PAAc Nanogels

24 Treatment of dry eye syndrome Topical application of PVP/PAAc nanogel dispersions in an experimental dry eye model in albino rabbits Dry eye syndrome is a chronic eye disease which is associated with symptoms of discomfort, visual disturbance and abnormal tear film from either tear deficiency or excessive tear evaporation

25 Topical application of PVP/PAAc nanogel dispersions in an experimental dry eye model in albino rabbits An experimental dry eye model in albino rabbits was carried out using atropine sulfate 1% eye drops The model produces some typical dry eye symptoms such as a significant reduction in the tear volume and tear break-up time (TBUT), corneal staining, and histopathological signs of dryness and inflammation. The prepared PVP/PAAc nanogels (1.5 w/v%, ph 7.4) were used for the treatment of the dry eye model, and the obtained results were compared with that of commercial carbomer gel Vidisic, 0.2%

26 Untreated dry eye model Ulcer

27 Treated dry eye model

28 Conclusion It can be concluded that radiation is a very effective tool for controlling the degradation and cross-linking of natural occurring polymers and the synthesis of relative economic, environmentally friendly super-absorbent hydrogels which may potentially be used in personal care products industry, in agriculture as a growth promoter, and in medical uses as drug delivery under control release to specific sites. 28

29 Many Thanks for your kind attention 29