2. Description of Related Art It is well known that limiting the exposure of oxygen-sensitive products to oxygen maintains the quality and extends the shelf-life of the product. For instance, by limiting the oxygen exposure of oxygen sensitive food products in a packaging system, the quality of the food product is maintained, and food spoilage is avoided. Such packaging also keeps the product in inventory longer, thereby reducing costs incurred from waste and restocking. In the food packaging industry, several means for limiting oxygen exposure have already been developed, including modified atmosphere packaging (MAP), vacuum packaging and oxygen barrier film packaging.

Another, more recent, means for limiting oxygen exposure involves incorporating an oxygen scavenger into the packaging structure. Incorporation of a scavenger in the package can consume oxygen present in the package after filling of the package with a product. In addition, such incorporation can provide a means of intercepting and scavenging oxygen as it passes through the walls of the package, before the oxygen could reach the packaged product, thus providing even more protection to the packaged product.

An oxidizable organic compound that has been used as an oxygen scavenger in oxygen scavenging packaging materials is ethylene/methyl acrylate/cyclohexenylmethyl acrylate terpolymer (EMCM). EMCM can be readily made following the teachings of international patent publication WO 99/48963, incorporated herein by reference. Typically, EMCM is prepared by, first, forming an ethylene/methyl acrylate copolymer and, second, transesterifying some of the methyl acrylate units with cyclohexenylmethyl alcohol. Another oxidizable

organic compound that has been used is ethylene/cyclohexenylmethyl acrylate copolymer (ECHA), which can be prepared by high pressure copolymerization.

Although effective, the methods known in the art for making EMCM and ECHA have a number of shortcomings. Transesterification of EMCM will bring about somewhat less than 100% conversion of methyl acrylate units of the ethylene/methyl acrylate copolymer to cyclohexenylmethyl acrylate. Transesterification also can impose a need for removal of by- products from the reaction vessel, and thus complicate the process. High pressure copolymerization requires specialized, expensive equipment in order to perform the reaction.

Thus, it is desirable to have a method of making oxygen scavenging polymers, especially such polymers comprising cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate units, that is inexpensive, highly efficient, and convenient.

SUMMARY OF THE INVENTION In one embodiment, the present invention is directed to a method of making a homopolymer of cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate, comprising: (i) combining a suspending agent, a free radical initiator, and the cyclohexenylmethyl acrylate or the cyclohexenylmethyl methacrylate as a monomer in an aqueous solution; (ii) agitating the aqueous solution, to form droplets of the monomer in the aqueous solution; (iii) activating the free radical initiator; (iv) and polymerizing the cyclohexenylmethyl acrylate or the cyclohexenylmethyl methacrylate, to form the homopolymer.

In another embodiment, the present invention is directed to a method of making a copolymer of cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate and a second alkyl acrylate, comprising: (i) combining a suspending agent, a free radical initiator, the cyclohexenylmethyl acrylate or the cyclohexenylmethyl methacrylate as a monomer, and the second alkyl acrylate as a monomer, in an aqueous solution; (ii) agitating the aqueous solution, to form droplets of the monomers in the aqueous solution; (iii) activating the free radical initiator ; (iv) and polymerizing the monomers, to form the copolymer. Preferably, one of the pendantly-substituted alkyl acrylate monomers is CHAA, and the other is cyclohexenylmethyl methacrylate (CHMA).

In yet another embodiment, the present invention is directed to a method of making a copolymer of cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate and a vinyl compound, comprising: (i) combining a suspending agent, a free radical initiator, the

cyclohexenylmethyl acrylate or the cyclohexenylmethyl methacrylate as a monomer, and the vinyl compound as a monomer, in an aqueous solution; (ii) agitating the aqueous solution, to form droplets of the monomers in the aqueous solution; (iii) activating the free radical initiator; (iv) and polymerizing the cyclohexenylmethyl acrylate or the cyclohexenylmethyl methacrylate and the vinyl compound, to form the copolymer. Preferably, CHAA is used, and the vinyl compound is vinyl acetate, acrylonitrile, styrene, or acrylic acid.

The present invention has the advantages of providing homopolymers that can consist of essentially 100% oxygen scavenging units, or copolymers comprising a high proportion of oxygen scavenging units. These polymers are made by a convenient, inexpensive method for the synthesis of such homopolymers or copolymers.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS The present invention is directed to methods of making a polymer comprising cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate by suspension polymerization. The polymer can be a homopolymer comprising the cyclohexenylmethyl acrylate or the cyclohexenylmethyl methacrylate, or the polymer can be a copolymer or terpolymer comprising cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate and another unit or units, such as a second alkyl acrylate or a vinyl compound.

"Homopolymer,"as used herein, is a polymer consisting essentially of monomer units of a single structure, with any monomer units of a different structure that may be present being at levels below about 1 mol%, preferably below about 0.1 mol%. The structures of monomer units of cyclohexenylmethyl acrylate and cyclohexenylmethyl methacrylate are well-known in the art. One of ordinary skill in the art will recognize that a homopolymer made from cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate will have a saturated polyethylenic backbone.

Alternatively, the method of the present invention can be used to synthesize a copolymer of cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate and a second alkyl acrylate. The cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate may be referred to as a"first alkyl acrylate."By"copolymer"is meant a polymer consisting essentially of monomer units of two structures, with any monomer units of a different structure that may be present being at levels below about 1 mol%, preferably below about 0.1 mol%. The copolymer may be a random or a block copolymer, preferably a random copolymer. The first alkyl acrylate unit can comprise any mole percentage of the copolymer, preferably from about 5 mol% to about 99 mol%, with the balance essentially made up by the second alkyl acrylate unit.

By"monomer of a second alkyl acrylate"is meant a molecule with the structure I :

wherein a is-CH2- ; b is an integer from 1 to 3; X is hydrogen or methyl; and R is hydrogen, aryl of 6 to 20 carbons, substituted aryl of 6 to 20 carbons, alkyl of 1 to 20 carbons, substituted alkyl of 1 to 20 carbons, alkenyl of 2 to 20 carbons, substituted alkenyl of 2 to 20 carbons, cycloalkenyl of 4 to 20 carbons, or substituted cycloalkenyl of 4 to 20 carbons.

Substituents that can be present on the aryl, alkenyl, or cycloalkenyl groups include hydroxy, keto, carboxy, or halogen.

Preferably, R is a cycloalkenyl group having structure II : wherein ql, q2, q3, q4, and r are independently selected from hydrogen, methyl, or ethyl; m is- (CH2) n-, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of ql, q2, q3, and q4 is also hydrogen.

More preferably, R is cyclohexenyl (i. e. n = 1 and ql, q2, q3, q4, and r are each hydrogen) and X is hydrogen or methyl. When R is cyclohexenyl and X is hydrogen, the pendantly-substituted alkyl acrylate is cyclohexenylmethyl acrylate (CHAA). When R is cyclohexenyl and X is methyl, the pendantly-substituted alkyl acrylate is cyclohexenylmethyl methacrylate (CHMA).

Although the second alkyl acrylate can be cyclohexenylmethyl acrylate or cyclohexenylmethyl methacrylate, excluded from this embodiment are the situations where (a) the first alkyl acrylate is cyclohexenylmethyl acrylate and the second alkyl acrylate is

cyclohexenylmethyl acrylate or (b) the first alkyl acrylate is cyclohexenylmethyl methacrylate and the second alkyl acrylate is cyclohexenylmethyl methacrylate. These two situations are excluded from this embodiment because they are encompassed by the homopolymer embodiment described previously.

Preferably, in the second alkyl acrylate, X is hydrogen and R is selected from structure II. More preferably, the first alkyl acrylate is CHAA, and the second alkyl acrylate is CHMA ; or the first alkyl acrylate is CHMA, and the second alkyl acrylate is CHAA.

One of ordinary skill in the art will recognize that the copolymer made from CHAA, CHMA, or monomers of structure I will have a saturated polyethylenic backbone.

In yet another alternative, the method of the present invention can be used to synthesize a copolymer of CHAA or CHMA and a vinyl compound. The CHAA or CHMA may be referred to as the"first alkyl acrylate." The CHAA or CHMA are as described above. More preferably, the first alkyl acrylate is CHAA.

By"vinyl compound"is meant a monomer having the structure III: wherein R2 is selected from alkyl of 1 to 20 carbon atoms, substituted alkyl of 1 to 20 carbon atoms, alkenyl of 2 to 20 carbon atoms, substituted alkenyl of 2 to 20 carbon atoms, hydroxy, alkoxy of 1 to 20 carbon atoms, aryl of 6 to 20 carbon atoms, substituted aryl of 6 to 20 carbon atoms, keto of 1 to 20 carbon atoms, aldehyde of 1 to 20 carbon atoms, nitrile, or carboxy of 1 to 20 carbon atoms. Preferably, R2 is acetate, C1 carboxy, nitrile, or phenyl (i. e. the vinyl compound is vinyl acetate, acrylic acid, acrylonitrile, or styrene). More preferably, the vinyl compound is vinyl acetate.

One of ordinary skill in the art will recognize that the copolymer made from the first alkyl acrylate and the vinyl compound will have a saturated polyethylenic backbone.

The copolymer may be a random or a block copolymer, preferably a random copolymer. The acrylate unit can comprise any mole percentage of the copolymer, preferably from about 5 mol% to about 99 mol%, with the balance essentially made up by the vinyl unit.

The present invention is directed to a method of making a polymer comprising cyclohexenylmethyl acrylate (CHAA) or cyclohexenylmethyl methacrylate (CHMA). If the

polymer is a homopolymer of CHAA or CHMA, the method comprises: (i) combining a suspending agent, a free radical initiator, and the CHAA or CHMA as a monomer in an aqueous solution; (ii) agitating the aqueous solution, to form droplets of the monomer in the aqueous solution; (iii) activating the free radical initiator; (iv) and polymerizing the CHAA or CHMA, to form the homopolymer of CHAA or CHMA.

The CHAA or CHMA monomer is described above.

The suspending agent functions to enable droplets of the monomer to form in the aqueous solution, because a monomer of CHAA or CHMA is substantially poorly soluble or nonsoluble in aqueous solution. Any known suspending agent, such as polyvinyl alcohol, starch, gelatin, calcium phosphate, poly (acrylic acid) salts, gum arabic, or gum tragacanth, can be used. A preferred suspending agent is polyvinyl alcohol. Preferably, enough suspending agent is added to prevent agglomeration of particles of the polymer, but not so much as to emulsify the monomer and lead to a polymer latex instead of polymer beads.

The free radical initiator functions to provide free radicals to initiate polymerization.

This function occurs when the free radical initiator fragments under relatively high temperatures, such as about 80°C. The free radical initiator should be chosen such that its fragments are sufficiently soluble in droplets of the monomer to react with a monomer molecule and initiate polymerization. Any known free radical initiator, such as dibenzoyl peroxide, lauryl peroxide, or 2,2'-azobis (isobutyronitrile), can be used. A preferred free radical initiator is dibenzoyl peroxide.

One of ordinary skill in the art will recognize that reducing the concentration of the free radical initiator will tend to increase the molecular weight, because the reduced free radical initiator concentration will typically reduce the concentration of growing chains of the CHAA or CHMA polymer per droplet, and therefore polymerization of the growing chains will be less likely to terminate, by either coupling or disproportionation.

By"aqueous solution"is meant any solution comprising water as the solvent. In addition to the suspending agent, the free radical initiator, and the monomer, other solutes that may be present include organic or inorganic ions, including protons or hydroxide ions; organic or inorganic buffers; or other solutes known in the art, provided such solutes do not interfere with the suspension polymerization reaction described below. Compounds can be added to the solution with the intent of their entry into the solid formulation of the polymer; these compounds include plasticizers, pigments, chain-transfer agents, modifiers, etc.

The suspending agent, the free radical initiator, and the monomer can be combined in the aqueous solution in any order. The aqueous solution may be heated, stirred, or both to

facilitate the combination. If stirring is performed, it may be continuous with the agitating step described below. Alternatively, the process may be run on a continuous basis, wherein the suspending agent, the free radical initiator, and the monomer are added as needed to a reactor under continual agitation.

Once the aqueous solution is formed, it is agitated to form droplets of the monomer in the aqueous solution. The agitation can be by any appropriate technique, such as by a stir bar, paddle stirrer, or other known technique. The agitation should be of sufficient intensity and duration to form droplets of the monomer.

Once droplets of the monomer have formed, the free radical initiator is activated.

Typically, this is accomplished by heating the solution to a temperature at or slightly greater than the fragmentation temperature of the free radical initiator. Typically, the temperature to which the solution is heated is between about 60°C and about 90°C. This causes the free radical initiator to fragment. The resulting fragments each have a free radical electron, which renders them capable of extracting an electron from the ethylenic bond of a CHAA or CHMA monomer, thus initiating polymerization of the monomer.

Once polymerizing is initiated, it proceeds by free radical attack on a monomer molecule by the electron at the terminus of the growing homopolymer chain. If the concentration of free radical initiator is sufficiently low, the concentration of growing ends of the homopolymer chain can be low enough that termination of polymerization by chain coupling or disproportionation will be rare. As a result, homopolymers of the CHAA or CHMA of high molecular weight (> 25 kD) can be prepared.

The final result of polymerization is usually fine spheres or beads of the homopolymer.

The particle size depends on, among other variables, the reaction temperature, the ratio of monomer to water, the rate and efficiency of agitation, the nature and concentration of the suspending agent, and the nature of the monomer. The beads can then be extracted from the solution by filtration, or another appropriate method.

The beads will consist essentially of the homopolymer (and any additives provided to the solution for incorporation into the formulation of the polymer), although some residual monomer may be present. Monomer units present in the beads can be removed by evaporation, typically by the application of heat or vacuum.

After extraction and removal of monomer, the beads can be used or stored for use in forming any desired structure. For example, when the beads comprise a homopolymer of CHAA or CHMA, the beads can be used in the generation of an oxygen scavenging composition useful in forming an oxygen scavenging packaging article or a layer thereof. The

high concentration of oxidizable sites in the CHAA homopolymer makes it very useful in such an application. The oxygen scavenging capacity of a composition comprising CHAA homopolymer is given in Example 5, below.

In a further embodiment, the present invention is directed to a method of making a copolymer of CHAA or CHMA (a"first alkyl acrylate") and a second alkyl acrylate, comprising: (i) combining a suspending agent, a free radical initiator, the CHAA or CHMA as a monomer, and the second alkyl acrylate as a monomer, in an aqueous solution; (ii) agitating the aqueous solution, to form droplets of the monomers in the aqueous solution; (iii) activating the free radical initiator; (iv) and polymerizing the CHAA or CHMA and the second alkyl acrylate, to form the copolymer.

The method is substantially the same as that described above for the formation of the homopolymer, with exceptions described below. The second alkyl acrylate is as described above, and can be any pendantly-substituted alkyl acrylate of structure I, and is preferably CHAA (if the first alkyl acrylate is CHMA) or CHMA (if the first alkyl acrylate is CHAA).

Both monomers will typically enter the droplet and be available for chain extension of the copolymer. Typically, the copolymer produced will be a random copolymer, although a block copolymer produced by the method is also an aspect of the present invention.

After extraction and removal of monomer from the copolymer beads, the beads can be used or stored for use in forming any desired structure. For example, when the beads comprise a copolymer of CHAA and CHMA, the beads can be used in the generation of an oxygen scavenging composition useful in forming an oxygen scavenging packaging article or a layer thereof : The high concentration of oxidizable sites in the copolymer makes it very useful in such an application, and by adjusting the ratio of CHAA and CHMA units, the Tg of the copolymer can be adjusted as well.

In still a further embodiment, the present invention is directed to a method of making a copolymer of CHAA or CHMA (a"first alkyl acrylate") and a vinyl compound, comprising: (i) combining a suspending agent, a free radical initiator, and the CHAA or CHMA and the vinyl compound as monomers in an aqueous solution; (ii) agitating the aqueous solution, to form droplets of the monomers in the aqueous solution; (iii) activating the free radical initiator; (iv) and polymerizing the CHAA or CHMA and the vinyl compound, to form the copolymer.

The method is substantially the same as that described above. Preferably, the first alkyl acrylate is CHAA, and the vinyl compound is vinyl alcohol, vinyl acetate, vinyl acrylate, or styrene. More preferably, the vinyl compound is vinyl acrylate.

Both monomers will typically enter the droplet and be available for chain extension of the copolymer. Typically, the copolymer produced will be a random copolymer, although a block copolymer produced by the method is also an aspect of the present invention.

The following examples are included to demonstrate preferred embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventor to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

Examples Example 1. Suspension polymerization of cyclohexenylmethyl acrylate (CHAA) A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer was charged with 800 mL distilled water containing 2 g of polyvinyl alcohol (98% hydrolyzed, from JT Baker). The stirred solution was heated to 80 °C. To the solution, 200 g of CHAA containing 0.2 g dibenzoyl peroxide (BPO) were added dropwise in about 1 hr. The stirred monomer/water suspension mixture was kept at 80-90 °C for 2-3 hrs. After the exothermic phase of the reaction went to completion, the reaction mixture was heated to reflux.

Some excess monomer was removed by steam distillation. Then the mixture was cooled, the stirrer was stopped, and the polymeric beads were filtered through a paper filter. The

polymeric beads were washed with ethanol 4 times (4 x 100 mL). The product was dried in a vacuum oven at 50 °C overnight. Yield: 181.5 g (90.8%).

Example 2. Suspension polymerization of cyclohexenylmethyl methacrylate (CHMA) A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer was charged with 800 mL distilled water containing 2 g of polyvinyl alcohol (98% hydrolyzed, from JT Baker). The stirred solution was heated to 80 °C. Then, 200 g of CHMA containing 0.2 g BPO were added dropwise in about 1 hr. The stirred monomer/water suspension mixture was kept at 80-90 °C for 2-3 hrs. After the exothermic phase of the reaction went to completion, the reaction mixture was heated to reflux. Some excess monomer was removed by steam distillation. Then the mixture was cooled, the stirrer was stopped, and the polymeric beads were filtered through a paper filter. The polymeric beads were washed with ethanol 4 times (4 x 100 mL). The product was dried in a vacuum oven at 50 °C overnight. Yield: 196.4 g (98.2%).

Example 3. Suspension copolymerization of cyclohexenylmethyl acrylate (CHAA) and cyclohexenylmethyl methacrylate (CHMA) A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer was charged with 600 mL distilled water containing 1.5 g of polyvinyl alcohol (80% hydrolyzed, from Aldrich). The stirred solution was heated to 80 °C. A mixture of monomers containing 75 g of CHAA, 75 g of CHMA and 0.15 g BPO was added dropwise in about 1 hr.

The stirred monomer/water suspension mixture was kept at 80-90 °C for 2-3 hrs. After the exothermic phase of the reaction went to completion, the reaction mixture was heated to reflux.

Some excess monomer was removed by steam distillation. Then the mixture was cooled, the stirrer was stopped, and the polymeric beads were filtered through a paper filter. The polymeric beads were washed with warm water 5 times and with ethanol 2 times (2 x 100 mL).

The product was dried in a vacuum oven at 50 °C overnight. Yield: 138. 5 g (92.3%).

Example 4. Suspension copolymerization of cyclohexenylmethyl acrylate (CHAA) and cyclohexenylmethyl methacrylate (CHMA)

A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer was charged with 600 mL distilled water containing 1.5 g of polyvinyl alcohol (80% hydrolyzed, from Aldrich). The stirred solution was heated to 60 °C. A mixture of monomers containing 75 g of CHAA, 75 g of CHMA and 0.15 g BPO was added dropwise in about 1 hr.

The stirred monomer/water suspension mixture was kept at 60 °C for 8 hrs. The reaction mixture was cooled, the stirrer was stopped, and the polymeric beads were filtered through a paper filter. The polymeric beads were washed warm water 5 times and ethanol 4 times (4 x 100 mL). The product was dried in a vacuum oven at 50 °C overnight. Yield: 126.7 g (84.5%).

Example 5. Oxygen Scavenging Test of CHAA Homopolymer 30 g of CHAA homopolymer prepared according to Example 1 was blended with 170 g of EMAC (SP-2260, product of Chevron) and 10.6 g of EMAC based masterbatch containing 1 wt. % of cobalt oleate and 1 wt. % of a photoinitiator (tribenzoyl triphenylbenzene) on a Haake twin screw extruder at 170 °C. The resulting blend was then processed into a 1 mil thick monolayer film. A 100 cm2 (5 cm x 20 cm) film (0.56 g) was exposed for 1.6 minutes to 254 nm UV at 1 inch to receive 800 mJ/cm2. The oxygen scavenging was tested with 300 cc 1% 02 and 99% N2 at 4 °C, using a Mocon HS750. The results of the tests are given below in Table 1.

The oxygen scavenging uptake capacity is based on the total weight of the monolayer film.

Table 1. °2 Scavenging Measurements Using Mocon HS750 02 O2 Vol-O2 O2 O2 Uptake Time Meas. Instant Rate 02 Capacity Meas Used Uptake Avg. Rate (Days) Vol (cc/m2/day) (cc/m2/mil) (Vol%) (mL) (mL) (mL/g) (cc/m2/day) 0. 0 1. 02 3. 06 0. 00 0. 00 0. 00 0. 00 0. 00 1.1 0. 87 2. 57 0. 44 0. 79 20. 89 20. 89 22. 13 2.0 0.51 1.48 1.49 2.65 36.47 53.31 74.33 3.2 0. 12 0. 34 2. 60 4. 64 40. 53 47. 64 129. 90 4.2 0.04 0.11 2.82 5.04 33.47 11.08 141.10 7.2 0.01 0.03 2.90 5.19 20.24 1.39 145.23

Example 6. Suspension copolymerization of cyclohexenylmethyl acrylate (CHAA) and vinyl acetate (VA) A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer is charged with 600 mL distilled water containing 1.5 g of polyvinyl alcohol (80% hydrolyzed, from Aldrich). The stirred solution is heated to 70 °C. A mixture of monomers containing 75 g of CHAA, 75 g of VA and 0.15 g BPO is added dropwise in about 1 hr. The stirred monomer/water suspension mixture is kept at 70 °C for 5-6 hrs. The reaction mixture is cooled, the stirrer is stopped, and the polymeric beads are filtered through a paper filter. The polymeric beads are washed with warm water 5 times and with ethanol 2 times (2 x 100 mL).

The product is dried in a vacuum oven at 50 °C overnight.

Example 7. Suspension copolymerization of cyclohexenylmethyl acrylate (CHAA) and methyl methacrylate (MMA) A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer is charged with 600 mL distilled water containing 1.5 g of polyvinyl alcohol (80% hydrolyzed, from Aldrich). The stirred solution is heated to 80 °C. A mixture of monomers containing 75 g of CHAA, 75 g of MMA and 0. 15 g BPO is added dropwise in about 1 hr. The stirred monomer/water suspension mixture is kept at 80-90 °C for 2-3 hrs. After the exothermic phase of the reaction goes to completion, the reaction mixture is heated to reflux.

Some excess monomer is removed by steam distillation. Then the mixture is cooled, the stirrer is stopped, and the polymeric beads are filtered through a paper filter. The polymeric beads are washed with warm water several times and with ethanol 4 times (4 x 100 mL). The product is dried in a vacuum oven at 50 °C overnight.

Example 8. Suspension copolymerization of cyclohexenylmethyl acrylate (CHAA) and methyl acrylate (MA) A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer is charged with 600 mL distilled water containing 1.5 g of polyvinyl alcohol (80% hydrolyzed, from Aldrich). The stirred solution is heated to 60 °C. A mixture of monomers containing 75 g of CHAA, 75 g of MA and 0.15 g BPO is added dropwise in about 1 hr. The stirred monomer/water suspension mixture is kept at 60 °C for 7-8 hrs. The mixture is cooled,

the stirrer is stopped, and the polymeric beads are filtered through a paper filter. The polymeric beads are washed with water several times and with ethanol 4 times (4 x 100 mL). The product is dried in a vacuum oven at 40 °C overnight.

Example 9. Suspension copolymerization of cyclohexenylmethyl acrylate (CHAA) and styrene A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer is charged with 600 mL distilled water containing 1.5 g of polyvinyl alcohol (80% hydrolyzed, from Aldrich). The stirred solution is heated to 80 °C. A mixture of monomers containing 75 g of CHAA, 75 g of styrene and 0.15 g BPO is added dropwise in about 1 hr.

The stirred monomer/water suspension mixture is kept at 80-90 °C for 2-3 hrs. After the exothermic phase of the reaction goes to completion, the reaction mixture is heated to reflux.

Some excess monomer is removed by steam distillation. Then the mixture is cooled, the stirrer is stopped, and the polymeric beads are filtered through a paper filter. The polymeric beads are washed with warm water several times and with ethanol 4 times (4 x 100 mL). The product is dried in a vacuum oven at 50 °C overnight.

Example 10. Suspension copolymerization of cyclohexenylmethyl acrylate (CHAA) and acrylonitrile A 2000 mL 3-neck flask equipped with a condenser, thermocouple and mechanical stirrer is charged with 600 mL distilled water containing 1.5 g of polyvinyl alcohol (80% hydrolyzed, from Aldrich). The stirred solution is heated to 80 °C. A mixture of monomers containing 75 g of CHAA, 75 g of acrylonitrile and 0.15 g BPO is added dropwise in about 1 hr. The stirred monomer/water suspension mixture is kept at 65 °C for 7-8 hrs. The mixture is cooled, the stirrer is stopped, and the polymeric beads are filtered through a paper filter. The polymeric beads are washed with warm water several times and with ethanol 4 times (4 x 100 mL). The product is dried in a vacuum oven at 40 °C overnight.

All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the

compositions and methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

REFERENCES The following references, to the extent that they provide exemplary procedural or other details supplementary to those set forth herein, are specifically incorporated herein by reference.

Ching, T. Y., et al. PCT International Publication No. WO 99/48963 Sander, S. R., and Karo, W. Polymer Synthesis, p. 336. Vol. 1,2nd Ed., 1992 (Academic Press, New York).