Claims:1. A process for synthesizing a biodegradable polycarbonate polymer said process comprising the following steps:
i. epoxidation of at least one vegetable oil to obtain an epoxide of said vegetable oil and reacting said epoxide so obtained with carbon dioxide (CO2) in presence of a catalyst to form a cyclic carbonate; and

ii. performing ring opening polymerization (ROP) on said cyclic carbonate to obtain a mixture containing a crude polymer and precipitating said biodegradable polycarbonate polymer from said mixture.

2. The process as claimed in claim 1, wherein said vegetable oil is castor oil.

3. The process as claimed in claim 1, wherein said epoxide is reacted with CO2 at a temperature in the range of 90 to 140 °C for a time period of 2 to 8 hours with pressure in the range of 30 to 50 bars and in presence of predetermined amount of at least one polar solvent.

4. The process as claimed in claim 3, wherein said polar solvent is tetrahydrofuran.

5. The process as claimed in claim 1, wherein said catalyst is at least one selected from the group consisting of Zinc, Nickel and cobalt based salen complex.
6. The process as claimed in claim 1, wherein said ring opening polymerization is carried out in presence of at least one polar solvent in predetermined amounts and stannous octoate catalyst at a temperature in the range of 60 to 120 °C for a time period of 3 to 10 hours.

7. The process as claimed in claim 6, wherein said stannous octoate catalyst is Tin octanoate. , Description:FIELD
The present disclosure relates to the field of polymer chemistry, in particular to a biodegradable polycarbonate polymer based on bio resources, and also relates to a process for synthesizing the biodegradable polycarbonate polymer.
BACKGROUND
Demands of biodegradable polymeric materials have been increasing extensively all over the world. The mass production of polymers has already brought a negative impact on the environment, because majority of these polymers are non-biodegradable. Alternatively, research on developing biodegradable polymers has become increasingly important with the aim to reduce any further negative impact on the environment. Vegetable oil/plant oil based polymers are a good candidate in this context such as polyurethanes (PUs). Polyurethanes have many industrial applications such as coating, building and construction, transportation, furniture, bedding, etc. due to a wide range of properties due to the high number of functional groups present in the main chain of the vegetable oil.
Society is to a growing degree confronted with global warming, which is due to the increasing accumulation of Carbon dioxide (CO2) in the atmosphere. This results in climate change and serious environmental problems, which are closely correlated with greenhouse gas emissions from human activities. Among the greenhouse gases, carbon dioxide contributes more than 60% to global warming because of its huge emission amount. Thus utilisation of CO2 for preparing a polymer which is biodegradable helps in reducing the carbon footprint which the world is facing today. Polycarbonate manufactured from vegetable oil and carbon dioxide is a completely biodegradable polymer and contains higher number of functional groups, which makes this class of polymer making suitable for a wide number of applications.
There is great need for degradable, environment friendly polymeric materials that are non-toxic to human health over their prolonged use. The demand for such polymers is particularly high as food packaging material as well as health and personal care products, especially where individuals or the consumable materials are exposed to the polymer over prolonged periods. Biodegradability without generating toxic by-products both in vivo and ex vivo is indeed desirable in all new polymers.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a biodegradeable polycarbonate with high functionality, high polarity and flowability.
Another object of the present disclosure is to provide a process for synthesizing a biodegradable polycarbonate.
Still another object of the present disclosure is to provide an economic process for synthesizing the biodegradable polycarbonate.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages a process for synthesizing a biodegradable polycarbonate polymer. The process comprises mixing in a reaction vessel, vegetable oil, at least one oxidizing agent and a polar solvent. The oxidizing agent is added in a dropwise manner over a predetermined time period to obtain a reaction mixture. This reaction mixture is then poured in a predetermined amount of water to remove the unreacted oxidizing agent, to obtain an epoxide of the vegetable oil. The epoxide of the vegetable oil is then reacted with predetermined amount of carbon dioxide in a high pressure reaction vessel with constant stirring at a temperature in the range of 90 to 140 °C for a time period of 2 to 8 hours with pressure in the range of 30 to 50 bars in presence of predetermined amount of at least one polar solvent and predetermined amount of at least one transition metal atom-salen based catalyst system, to obtain a cyclic carbonate. This cyclic carbonate is then subjected to undergo ring opening polymerization (ROP) in presence of at least one polar solvent in predetermined amounts and stannous octoate catalyst at a temperature in the range of 60 to 120 °C for a time period of 3 to 10 hours, to obtain a mixture containing a crude polymer. This crude polymer so obtained is precipitated in predetermined amount of methanol followed by vacuum drying at a temperature in the range of 50 to 70 °C to obtain the biodegradable polycarbonate polymer.
Typically, the epoxide can be reacted with CO2 at a temperature in the range of 90 to 140 °C for a time period of 2 to 8 hours with pressure in the range of 3 to 50 bars and in presence of predetermined amount of at least one polar solvent. Typically, the vegetable oil (both edible and nonedible oils) can be at least one selected from the group consisting of castor oil, coconut oil, palm oil, sunflower oil, cottonseed oil, olive oil, peanut oil, rapeseed oil, sesame oil,soybean oil, almond oil, beechnut oil, brazilnut oil, cashew oil, hazelnut oil, macadamia oil, mongongo nut oil, pecan oil, pinenut oil, pistachio oil, walnut oil, all type of citrous oils such ase lemon oil, orange oil, grapefruit seed oil, jatropha seed oil, paradise oil, and pongamia oil. Typically, the polar solvent can be at least one selected from the group consisting of tetrahydrofuran, cyclohexanone, Dichloromethane, and 1,2 dichloroethane. Typically, the catalyst can be at least one selected from the group consisting of Zinc, Nickel and cobalt based salen complex. Typically, the ring opening polymerization can be carried out in presence of at least one polar solvent in predetermined amounts and stannous octoate catalyst at a temperature in the range of 60 to 120 °C for a time period of 3 to 10 hours. Typically, the stannous octoate catalyst can be at least one selected from the group consisting of Tin octanoate.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates synthesis of biodegradable polycarbonate polymer from castor oil and CO2.
Figure 2 illustrates FTIR spectra of castor oil, epoxide, cyclic carbonate and the polycarbonate.
Figure 3 illustrates the synthesis of biodegradable polycarbonate polymer.
DETAILED DESCRIPTION
Demands of biodegradable polymeric materials have been increasing extensively all over the world. The mass production of polymers has already brought a negative impact on the environment, because majority of these polymers are non-biodegradable. Moreover the society is to a growing degree confronted with global warming, which is due to the increasing accumulation of Carbon dioxide (CO2) in the atmosphere. This results in climate change and serious environmental problems, which are closely correlated with greenhouse gas emissions from human activities. Among the greenhouse gases, carbon dioxide contributes more than 60% to global warming because of its huge emission amount. Thus utilisation of CO2 for preparing a polymer which is biodegradable helps in reducing the carbon footprint which the world is facing today.
There is great need for degradable, environment friendly polymeric materials that are non-toxic to human health over their prolonged use. The demand for such polymers is particularly high as food packaging material as well as health and personal care products, especially where individuals or the consumable materials are exposed to the polymer over prolonged periods. Biodegradability without generating toxic by-products both in vivo and ex vivo is indeed desirable in all new polymers. Polycarbonate manufactured from vegetable oil and carbon dioxide is a completely biodegradable polymer and contains higher number of functional groups, which makes this class of polymer making suitable for a wide number of applications.
The present disclosure envisages a process for synthesizing a biodegradable polycarbonate polymer. The process for synthesizing the biodegradable polycarbonate polymer comprises epoxidation of at least one vegetable oil to obtain an epoxide of the vegetable oil and reacting the epoxide so obtained with carbon dioxide (CO2) in presence of a catalyst to form a cyclic carbonate. This cyclic carbonate is the nsubjected to ring opening polymerization (ROP) to obtain a mixture containing a crude polymer and precipitating the biodegradable polycarbonate polymer from the mixture.
Typically, the epoxide can be reacted with CO2 at a temperature in the range of 90 to 140 °C for a time period of 2 to 8 hours with pressure in the range of 30 to 50 bars and in presence of predetermined amount of at least one polar solvent.
Typically, the vegetable oil can be castor oil. The vegetable oil as used in the present disclosure is commercially purchased from the market as value added product and therefore, the specific source of the product is unknown. Typically, the vegetable oil (both edible and nonedible oils) can be at least one selected from the group consisting of castor oil, coconut oil, palm oil, sunflower oil, cottonseed oil, olive oil, peanut oil, rapeseed oil, sesame oil,soybean oil, almond oil, beechnut oil, brazilnut oil, cashew oil, hazelnut oil, macadamia oil, mongongo nut oil, pecan oil, pinenut oil, pistachio oil, walnut oil, all type of citrous oils such ase lemon oil, orange oil, grapefruit seed oil, jatropha seed oil, paradise oil, and pongamia oil. Typically, the polar solvent can be at least one selected from the group consisting of tetrahydrofuran, cyclohexanone, Dichloromethane, and 1,2 dichloroethane.
Typically, the polar solvent can be tetrahydrofuran.
Typically, the catalyst can be at least one selected from the group consisting of Zinc, Nickel and cobalt based salen complex.
Typically, the ring opening polymerization can be carried out in presence of at least one polar solvent in predetermined amounts and stannous octoate catalyst at a temperature in the range of 60 to 120 °C for a time period of 3 to 10 hours.
Typically, the stannous octoate catalyst can be Tin octanoate.
In an embodiment of the present disclosure, the process comprises mixing in a reaction vessel, vegetable oil, at least one oxidizing agent and a polar solvent. The oxidizing agent is added in a dropwise manner over a predetermined time period to obtain a reaction mixture. This reaction mixture is then poured in a predetermined amount of water to remove the unreacted oxidizing agent, to obtain an epoxide of the vegetable oil. The epoxide of the vegetable oil is then reacted with predetermined amount of carbon dioxide in a high pressure reaction vessel with constant stirring at a temperature in the range of 90 to 140 °C for a time period of 2 to 8 hours with pressure in the range of 30 to 50 bars in presence of predetermined amount of at least one polar solvent and predetermined amount of at least one transition metal atom-salen based catalyst system, to obtain a cyclic carbonate. This cyclic carbonate is then subjected to undergo ring opening polymerization (ROP) in presence of at least one polar solvent in predetermined amounts and stannous octoate catalyst at a temperature in the range of 60 to 120 °C for a time period of 3 to 10 hours, to obtain a mixture containing a crude polymer. This crude polymer so obtained is precipitated in predetermined amount of methanol followed by vacuum drying at a temperature in the range of 50 to 70 °C to obtain the biodegradable polycarbonate polymer.
Typically, the yield of the polycarbonate polymers can be calculated and analyzed by FT-IR spectra, 13C-NMR analysis, TGA and DSC.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
Experiment:
First set of examples: Synthesis of a biodegradable polycarbonate polymer.
In each case, reaction vessels were charged with 10 gm of castor oil and 100 ml of dichloromethane (DCM). 20 gm of metachloroperbenzoic acid (MCPBA) in dichloromethane solvent was then added drop wise. In different instances, the reaction was continued at various time intervals, between 2 – 4 hours in nitrogen atmosphere at various temperature ranges between 0 – 5 °C to obtain reaction mixtures. Each of the reaction mixtures was then poured into sufficient amounts of demineralised water to remove extra amount of unreacted MCPBA, to obtain epoxides of the castor oil.
In each case, 10 gm of the epoxide was then charged into a high pressure reaction vessel in 150 ml of tetrahydrofuran. 1gm of Zinc salen complex catalyst was then added followed by charging of the high pressure reaction vessel with CO2 till the pressure was 13 bar. The reaction was carried out at a temperature of 120 °C for 7 hours. Then the high pressure reaction vessel was depressurized and the crude product was washed with sufficeient amount of methanol for 2-3 times to obtain cyclic carbonates.
In each case, the cyclic carbonate was used as a starting material for synthesizing the biodegradable polycarbonate polymer. 8 gm of the cyclic carbonate was then charged into a reaction vessel. 100 ml of tetrahydrofuran (THF) and 0.02 gm of stannous octanoate was then added to the reaction vessel containing the cyclic carbonate. The reaction was then carried out for 7 hours at 80 °C under Nitrogen atmosphere to obtain a mixture containing a crude polymer. This crude polymer was then precipitated using sufficient amount of methanol followed by drying in vacuum oven for 2 hours to obtain the biodegradable polycarbonate polymer.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
? a simple and economic process for synthesizing a biodegradable polycarbonate polymer; and
? a process which synthesizes a biodegradable polycarbonate polymer with high functional group in the polymer backbone;

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.