Title of Invention

A METHOD FOR SYNTHESIS OF POLYMERS AND COPOLYMERS

Abstract

This invention discloses a process of activated monomer ring opening mode of polymerization for producing a polymer/copolymer from a corresponding cyclic monomer such as lactide and lactones with an active catalyst selected from simple halides containing Group 8 metals along with mediating agents. The synthesized polymer/copolymer was analyzed and found to have high number average molecular weight (Mn) with desired physical properties.

Full Text

PRIOR ART: Synthetic petrochemical-based polymers have had a tremendous industrial Impact since the 1940s. Despite the numerous advantages of these materials, two major drawbacks remain to be solved, namely, the use of nonrenewable resources in their production and the ultimate fate of these large-scale commodity polymers. Due to their unique properties, biodegradable polymers have long been considered as alternative environmentally friendly polymers, and the spectacular advances achieved over the last 30 years in the synthesis, manufacture, and processing of these materials have given rise to a broad range of practical applications from packaging to more sophisticated biomedical devices. Of the variety of biodegradable polymers known, linear aliphatic polyesters are particularly attractive and most used. Notably these polymers are not only biodegradable (the aliphatic polyester backbone is intrinsically sensitive to water and heat) but also bloassimilable, since their hydrolysis in physiological media gives nontoxic components that are eliminated via the Krebs cycle as water and carbon dioxide. Furthermore, the influence of the rheological and physical characteristics of these polymers should not be underestimated. Spectacular variations in physical properties can al^o be achieved during the polymer processing itself, through orientation, blending, branching, cross-linking, or plasticization. Indeed, these biodegradable polymers may well offer a practical solution to the ecological problems associated with bioresistant wastes. Flexible films, rigid containers, drink cups, and bottles are representative products already available in the marketplace. Numerous medical applications have also been considered for both surgical and pharmacological use (Fig. 1.). Historically, the use of synthetic biodegradable polymers as sutures started in the 1970s, the most widely used bloassimilable sutures being Dexon and Vicryl. Besides tissue repairing and engineering, biodegradable implants have also been used for fixation of fractured bones and joints. Accordingly, several orthopedic devices are commercially available such as the ligatlng clips and bone pins produced. With these biodegradable and bioassimilable devices, there are no particular precautions necessary for their use and no need for a removal operation, which is highly advantageous compared with metal implants. I I One of the many methods in synthesizing these polymers is the ring opening ; polymerization of the corresponding cyclic lactone monqmers or lactide. , RING OPENING POLYMERIZATION Many catalyst systems have been evaluated for the polymerization of lactide and lactones including complexes of aluminum, zinc, tin, and lanthanides. Even strong bases such as metal alkoxldes have been used \N\\h some success. Depending on the cata(yst system and reaction conditions, almost all conceivable mechanisms have been proposed to explain the kinetics, side reactions, and nature of the end groups observed in these polymerizations. Tin compounds, especially tln(ll) bi8-2-ethylhexanoic acid (tin octoate), are preferred for the bulk polymerization due to their soluWIity in molten state, high catalytic activity, and low rate of racemization of the polymer. Conversions of >90% and less than 1 % racemization can be obtained while providing polymer with high molecular weight. The polymerization of lactide and lactones using tin octoate is generally thought to occur via a coordination-insertion mechanism. High molecular weight polymer, good reaction rate, and low levels of racemization are observed with tin octoate-catalyzed polymerization. Typical conditions for polymerization are 180±210 °C, tin octoate concentrations of 100±1000 ppm, and 2±5 h to reach ca. 95% conversion. The polymerization is first order in both catalyst and monomer. Frequently hydroxyl-containing initiators such as l-octanol are used to both control molecular weight and accelerate the reaction. Copolymers of lactide with other cyclic monomers such as caprolactone can be prepared using similar reaction conditions. These monomers can be used to prepare random copolymers or block polymers because of the end growth polymerization mechanism. The coordination-insertion ring opening mode of polymerization is the most popular because of its capability in producing polymers with narrow molecular weight distribution. A large variety of metal complexes containing alkyl, alkoxide, carboxylates and oxides have been reported to possess good activity. Tin alkoxldes being the most popular route often envisages initiators of,the composition Sn(0R)2. Other metal alkoxldes or aryloxides containing aluminum, lithium, titanium and some lanthanides have been reported. A plethora of blo-compatible metal based Initiators have also been reported recently. These include examples from zinc, magnesium and calcium. In the 1980s, calcium ammoniate was popularly used for the ring opening polymerization of e-caprolactone. Extreme hydrolytic sensitivity and limited solubility in organic solvents restricted its use. Derivatives containing iron namely alkoxides, porphyrins and acetates have been used previously. Key issue in commercialization is the catalyst residue. In spite of the versatile applications of Lewis acids in organic synthesis, their use in polymer chemistry has been quite limited. In the recent years, the increasing need to search alternative polymeric materials to those based on non-renewable petroleum resources, along with the desire to produce environmentally benign biodegradable plastics has provided active impetus towards the polymerization of cyclic esters. Aliphatic polyesters have been implicated for biomedical applications such as delivery medium for the controlled release of drugs and biodegradable surgical sutures. Polylactones have potential utility for such usage as a result of their permeability, biocompatibility and biodegradability. One of the convenient strategies in synthesizing these polymers is the ring opening polymerization of the corresponding cyclic lactone monomers or functionally related compounds. Although a multitude of initiators are known for such polymerizations, the major hurdle regarding the commercialization of such processes is the difficulty in removing catalyst residues and the cytotoxicity associated with such residues, which limit the application of these polymers in biomedical applications. An attractive process is envisioned to be engineered upon new catalysts that have environmentally benign metals that are constituents in the mammalian anatomy so that the residues are potentially harmless. Iron based initiators have been known. The biomedical applications of such polymers require low levels of impurities, so there Is great impetus for the development of active catalysts that contain low toxicity ttietals. Iron is attractive in this regard, but there are few reports of iron complexes for such polymerization. Ferric oxide, iron porphyrins, and simple iron salts including carboxylates and alkoxides have been used, but the polymerizations are sluggish, even at high temperature (120-21CC, hours or days), racemization invariably occurs for lactide polymerizations (especially at longer reaction times), and mechanistic analysis is frequently hindered by a lack of knowledge of precatalyst structure, often because of sample inhomogeneity. Interestingly, no detailed investigation has been reported using simple halides containing Group 8 metals. The feasibility of using metal halides as catalysts prompted the Inventors to investigate in details the ring opening polymerization characteristics using iron chloride towards e-caprolactone (CL), 5-valerolactone (VL), P-butyrolactone (BL) and lactide (LA). The extensive use of readily available and environmentally benign metal halides as catalysts has not been investigated extensively. BRIEF DESCRIPTION OF DRAWINGS: Fig.1. Practical applications of biodegradable polymers. Fig. 1A. Plot of Mn (vs polystyrene standards) vs [CL]o/[Cat]o for CL polymerization at 2rC using FeCIa- 6H2O, RuCly H2O and FeCi? 4H2O. Fig. 2. Plot of A/fn (vs polystyrene standards) vs [M]o/[Fe]o for CL, VL and BL polymerization at 27 "C using FeCly 6H2O. Fig. 2A. Plot of Mn (vs polystyrene standards) vs [VL]d/[Cat]o for VL polymerization at 27'C using FeCiy 6H2O, RuCly H2O and FeCl2- 4H2O. Fig. 3. Plot of Mn vs feed ratio of CLA/L/BL to BnOH at 27 "C. Fig. 3A. Plot of Mn vs feed ratio of CL to BnOH at 27 «C. Fig. 4. Semilogarithmic plots of CL conversion in time initiated by FeCl3-6H20: [monomer]/[catalyst] = 200 at 27 "C. Fig. 4A. Plot of Mn vs feed ratio of VL to BnOH at 27 "C. Fig. 5. MALDI-MS of the crude product obtained from a reaction between CL and FeCl3-6H20 along with BnOH in 15:1:2 ratio. Fig. 6. Co-polymers of CL, VL, BL and LA.. . Fig. 7. Co-polymer of CL and VL. Fig 8 MALDI-MS of the crude product obtained from a reaction between CL and RUCI3H2O along with BnOH in 15:1:2 ratio. Fig 9 ^HNMR spectrum of the crude product obtained from a reaction between CL and RUCI3 H2O along with BnOH in 15:1:2 ratio DESCRIPTION OF THE INVENTION FeCIa- 6H2O, RuCia- H2O and FeCI/ 4H2O are found to be bulk polymerization catalysts for the ring opening polymerization of £-caprolactone, 5-valerolactone and P-butyrolactone. These polymerizations can be significantly enhanced by conducting them in the presence of appropriate amounts of different alcohols. The major initiation pathway in the polymerization is found to proceed via the activated monomer mechanism and depending on the nature of the alcohol used, poly(lactones) with different end groups can be synthesized. Such polymerizations constitute an economical process, employing readily available inorganics as catalysts and do not necessitate solvents. The overall system is green and eco friendly. The study began with the observation that anhydrous FeCia alone can be used catalytically for the bulk polymerization of CL, VL and BL respectively producing appreciably high number average molecular weight (A/fn) polymers. Since it is more practical to use hydrated FeCIa, tal Table 1 Results of CL, VL and BL polymerization using anhydrous FeCIa at IT'O. Entry Monomer Initiator' [M]o:[Fe]o:[l]o /"(min) Yield M^l MJMn (M) (I) ratio (%) ^^0 1 CL None 200:1:0 60.0 100 1.94/2.28 1.87 2 CL H2O 200:1:5 26.4 100 3.89/0.46 2.06 3 VL None 200:1:0 1.8 100 3.10/2.00 1.39 4 VL H2O 200:1:5 0.9 " 100 7.28/0.40 2.26 5 BL None " 200:1:0 0.6 100 1.22/1.72 1.78 ^6 BL H2O 200:1:5 0.3 100 2.48/0.35 1.76 a. Time of polymerization measured by quenching tiie polymerization reaction when all monomer was found consumed. b. Measured by GPC at ll^C in THF relative to polystyrene standards with Mark- Houwink corrections for Mn in the case of CL polymerizations. c. Calculated from MWMo([M]o/[Fe]o) for cases where no water is used and MWMo([M]o/[l]o)+MWwater for cases using water. Various polymerizations were, performed using CL, VL and BL Independently with commercially available FeCly 6H2O, under different conditions of stoichiometry, temperature and in the presence of several alcohol initiators as indicated in Table 2-4. These trials were performed under bulk conditions, Analysis of the results for CL polymerization using FeCiy 6H2O reveals that there is an increase in the molecular weight (Mn) of the poly(caprolactone) with an increase in the ratio between monomer and catalyst along with an improvement in molecular weight distributions (MWDs) (Entries 1-5 of Table 2). In the presence of an alcohol, for a given monomer initiator ratio, reasonable degree of control was reflected in terms of lower MWDs (Entry 1 Vs Entries 10-13 in Table 2) and enhanced molecular weights JMn) of the i-esulting polymers. In such cases the polymerization was found to proceed to completion much faster as reflected by the time. At 80°C, the polymerization proceeds rapidly where as at CC and IS^C, It is slower and the changes in Mn or MWDs are not significant when compared to the results obtained at 27 "C (Entry 1 vs Entries 6, 8 and 9 in Table 2). The Plot of Mn with [CL]o/[Fe]o ratio using FeClj 6H2O are depicted in Fig. 2. The plots are linear indicating that there is a continual rise in Mn with an increase in [CL]o/[Fe]o ratio. For RuCl3-H20 and FeClz4H20 the trends were similar as compared to the reactions catalyzed by FeCiyeHzO. The variations of Mn with [CL]o/[Cat]o ratio are depicted in Fig. 1A. The plots are linear Indicating that there is a continual rise in Mn with an increase In [CL]o/[Cat]o ratio. (Cat) (I) CO :[l]o ratio (%) Mth'xIO"'* 1 FeCl36H20 None 27 200:1:0 27.0 100 3.61/2.28 2.22 2 FeCb-SHzO None 27 400:1:0 1.25(h) . 100 5.83/4,56 2.17 3 FeCla-BHzO None 27 800:1:0 4.25(h) 100 8.63/9.12 1.70 4 FeCla-SHzO None 27 1000:1:0 10.25(h) 100 10.41/11.40 1.49 » 5 FeCb-BHjO None 27 1200:1:0 13.26(h) 100 12.52/13.68 1.28 6 FeCb-BHaO None 80 200:1:0 6.0 100 5.01/2.28 2.03 7 FeCl3-6HjO None 80 1000:1:0 15.0 100 3.88/11.40 2.06 8 FeCl3-6H20 None 15 200:1:0 1.25(h) 100 5.72/2.28 2.08 9 FeCls-eHjO None 0 200:1:0 3.25(h) 100 6.33/2.28 2.03 10 FeCla-eHjO BnOH 27 200:1:5 16.8 100 6.73/0.47 1.26 11 FeCla-eHjO EtOH 27 200:1:5 22.8 100 5.98/0.46 1.54 12 FeCl3-6H20 /-PrOH 27 200:1:5 15.6 100 7.00/0.46 1.67 13 FeCl3-6H20 Glycol 27 200:1:5 21.6 100 8.20/0.46 1.38 14 RuCIs- None 27 200:1:0 57.6 100 3.98/2.28 2.28 H2O 15 RuCla'HjO None 27 400:1:0 2.33(h) 100 5.55/4.56 2.02 16 RUCI3H2O None 27 800:1:0 5.75(h) 100 9.25/9.12 1.38 17 RuCia-HjO None 27 1000:1:0 7.50(h) 100 10.81/11.40 1.24 18 RuCla-HzO None 27 1200:1:0 10.60(h) 100 13.07/13.68 1.20 19 RUCI3H2O None 80 200:1:0 11.0 100 4.80/2.28 1.92 20 RuCb-HjO None 0 200:1:0 4.5(h) 100 3.87/2.28 1.84 21 RuCls-HjO BnOH 27 200:1:5 42.0 100 8.41/0.47 1.14 22 RuCla'HzO EtOH 27 200:1:5 54.6 100 8.47/0.46 1.39 23 RUCI3H2O /-PrOH 27 200:1:5 ' 39.6 100 6.60/0.46 1.21 24 RuCl3H20 Glycol 27 200:1:5 49.8 100 5.74/0.46 1.80 25 FeCl2-4H20 None 27 -200:1:0 24.0(h) 100 4.85/2.28 2.15 26 FeCl2-4H20 None 27 400:1:0 25.5(h) 100 6.83/4.56 1.69 27 FeCl2-4H20 None 27 800:1:0 27.0(h) 100 8.11/9.12 1.46 28 FeCl2-4H20 None 27 1000:1:0 29.0(h) 100 8.92/11.40 1.40 29 FeCl2-4H20 None 27 1200:1:0 31.2(h) 100 10.36/13.68 1.25 30 FeCl2-4H20 None 80 200:1:0 11.0(h) 100 3.52/2.28 1.92 31 FeCl2-4HaO None 0 200:1:0 36.0(h) 100 5.08/2.28 1.89 32 FeCl2-4H20 BnOH 27 200:1:5 14.0(h) 100 8.21/0.47 1.43 33 FeCl2-4H20 EtOH 27 200:1:5 15.0(h) 100 4.19/0.46 1.64 34 FeCl2-4HaO /-PrOH 27 200:1:5 14.5(h) 100 5.23/0.46 1.56 35 FeCl2-4H20 Glycol 27 200:1:5 16.0(h) 100 5.35/0.46 1.41 a. Time of polynnerization measured by quenching the polymerization reaction when all monomer was found consumed, b. Measured by GPC at 27 X in THF relative to polystyrene standards with Mark- Houwink corrections for Mn [71]. c. Calculated from MWcL([CL]o/[Cat]o) for cases where no alcohol is used and MWCL([CL]O/[I]O)+I^/1WROH for cases using alcohol. Having obtained encouraging results with CL, we proceeded towards investigating polymerizations using VL and BL employing the same metal salts under analogous conditions. These results using VL are summarized in Table 3. The Plot of /Wn with [VL]o/[Fe]o ratio using FeClj 6H2O are depicted in Fig. 2. The plots are linear indicating that there is a continual rise in Mn with an increase in |yL]o/[Fe]o ratio. VL has a greater tendency to undergo ring opening polymerization reaction when compared to CL. At 27 °C (Table 3), FeCly 6H2O, RuClj H2O and FeCI? 4H2O yielded good results. Again th^ Mn values were found to increase with an increase in [VL]o/[Cat]o (Entries 1-5, 11-15 and 21-25 of Table 3). In the presence of alcohols, better control of the polymerization reaction was reflected in terms of lower MWDs along with a reduction in the polymerization reaction time. The plot of /Wn vs [VL]o/[Cat]o ratio for FeClj 6H2O, RuCly H2O and FeCly 4H2O (Fig. 2A) is linear for eacli case. Table 3 Results of VL polymerization using FeCIs- 6H2O, RuCly H2O and FeCl2' 4H2O. Entry Catalyst Initiator Temp. [VLJoi ^(min) Yield M„^/ MJM„ "==« M.-MO- [i]o ratio 1 FeCls-eHjO None 27 200:1:0 0.96 100 7.43/2.00 2.07 2 FeCla'SHaO None 27 400:1:0 1.56 100 8.17/4.00 1.96 3 FeCla'SHzO None 27 800:1:0 3.00 100 9.78/8.00 1.73 4 FeCla-eHaO None 27 1000:1: 3.48 100 10.59/10.00 1.63 0 5 FeCl3-6H20 None 27 1200:1: 3.90 100 11.34/12.00 1.56 0 6 FeCla-eHjO None 0 200:1:0 13.98 100 6.49/2.00 1.99 7 FeCla-eHzO BnOH 27 200:1:5 0.78 100 6.17/0.41 1.78 8 FeCla-eHjO EtOH 27 200:1:5 1.08 100 5.77/0.40 1.53 9 FeCl3-6H20 /-PrOH 27 200:1:5 0.72 100 5.62/0.41 1.49 10 FeCl3-6H20 Glycol 27 200:1:5 0.90 100 7.10/0.41 1.47 11 RUCI3H2O None 27 200:1:a 1.92 100 5.12/2.00 2.37 12 RUCI3H2O None 27 400:1:0 3.60 100 6.56/4.00 2.09 13 RuCia-HzO None 27 800:1:0 6.00 100 9.61/8.00 1.61 14 RUCI3H2O None 27 1000:1: 7.20 100 11.00/10.00 1.47 0 15 RuCla-HzO None 27 1200:1: 8.28 100 12.60/12.00 1.32 0 16 RuCb-HaO None 0 200:1:0 15.60 100 2.17/2.00 1.30 17 RUCI3H2O BnOH 27 200:1:5 1.56 100 5.50/0.41 1.83 18 RuCla-HzO EtOH 27 200:1:5 1.80 100 3.67/0.40 1.41 19 RuCls-HjO /-PrOH 27 200:1:5 1.69 100 5.61/0.41 1.22 20 RuCla-HzO Glycol 27 200:1:6 1.74 100 2.18/0.41 1.19 21 FeCl2-4H20 None 27 200:1:0 2.33(h) 100 8.27/2.00 2.06 22 FeCl2-4H20 None 27 400:1:0 3.00(h) 100 10.73/4.00 1.70 23 FeCl2-4H20 None 27 800:1:0 4.00(h) 100 12.79/8.00 1.51 24 FeCl2-4H20 None 27 1000:1: 4.50(h) 100 14.20/10.00 1.41 0 25 FeCl2-4H20 None 27 1200:1: 5.10(h) 100 15.91/12.00 1.33 0 26 FeCl2-4H20 None 80 200:1:0 1.50(h) 100 5.89/2.00 2.12 27 FeCl2-4H20 None ,0 200:1:0 6.00(h) 100 10.18/2.00 1.53 28 FeCl2'4H20 BnOH 27 200:1:5 1.66(h) 100 14.44/0.41 1.37 29 FeCl2-4H20 EtOH 27 200:1:5 1.90(h) 100 7.76/0.40 1.39 30 FeCl2-4H20 /-PrOH 27 200:1:5 1.69(h) 100 5.86/0.41 1.77 31 FeCl2-4H20 Glycol 27 200:1:5 1.70(h) 100 8.85/0.41 1.27 a. TInne of polymerization measured by quenching the polymerization reaction when ail monomer was found consumed. b. Measured by GPC at 27'C in THF relative to polystyrene standards. c. Calculated from MWvL([VL]o/[Cat]o) for cases where no alcohol is used and MWVL([VL]O/[I]O)+IVIWROH for cases using alcohol. On a similar basis, polymerizations were conducted using FeCly 6H2O and BL and the results are enumerated in Table 4.The results follow the general trends discussed for the other polymerizations using FeClj 6H2O. Again the plot of Mn vs [BL]o/[Fe]o is found to be linear (Fig 2). Table 4 1^ Results of BL polymerization using FeCly 6H2O. Entry Initiator Temp. [BL]o:[Fe]o:[l]o f Yield M^l MJMn (I) ("C) ratio (min) (%) ^^c^io-4 1 None 27 200:1:0 0.24 100 2.42/1.72 1.96 2 None 27 400:1:0 0.54 100 3.02/3.44 1.60 3 None 27 800:1:0 1.14 100 3.19/6.88 1.37 4 None 27 1000:1:0 1.50 100 4.54/8.60 1.40 5 None 27 1200:1:0 2.10 100 5.03/10.32 1.32 6 None 0 200:1:0 _ 12.00 100 1.31/1.72 1.76 7 BnOH 27 200:1:5 0.18 100 4.49/0.35 1.25 8 EtOH 27 200:1:5 0.27 100 1.84/0.35 1.56 9 /-PrOH 27 200:1:5 0.19 100 3.37/0.35 1.63 10 Glycol 27 200:1:5 0.24 100 2.99/0.35 1.62 a. Time of polymerization measured by quenching the polymerization reaction when all monomer was found consumed. b. Measured by GPC at 27'C in THF relative to polystyrene standards. c. Calculated from MWBL([BL]o/[Fe]o) for cases where no alcohol is used and MWBL([BL]O/[I]O)+MWROH for cases using alcohol. The results using anhydrous FeCis and H2O as an initiator are similar to those using FeCly 6H2O, RuClj H2O and Fed? 4H2O for CL, VL and BL polymerizations (Entries 2, 4 and 6 of Table 1 vs Entry 1 of Tables 2-4). This indicates that such polymerizations can be mediated using H2O. Similarly, other stronger nucleophlles such as alcohols may be used. We have studied the effect of various alcohols (Tables 2-4) and found that the polymerizations proceed much faster in their presence. Moreover, some degree of control in terms of improvements in the MWDs was noticed but living polymerization was never observed. There was no general trend observed to explain the relative behaviour of the different alcohols in the different lactone polymerizations discussed using FeCl3-6H20, RuClyH20 and FeCl2-4H20. In the presence of different alcohols (Tables 2-4), the observed molecular weights of the polymers were found to be much higher in magnitude than those calculated. Hence It is reasonable to conclude that the rates of initiation and propagation are much more rapid than that of chain transfer. As a consequence, a better control over A/fn is observed. For polymerizations where there is slow initiation or rapid trans-esterification, the observed Mn is lower in magnitude than those calculated. The dependence of molecular weight (Mn). upon varying the feed ratio of CL, VL and BL (Fig. 3.) to benzyl alcohol (BnOH) as an initiator was examined using FeCl3-6H20. The molecular weight (^fn) increased almost linearly with increasing feed ratio of monomer to BnOH. The dependence of molecular weight (Mn) upon varying the feed ratio of CL (Fig. 3A) and VL (Fig. 4A) to benzyl alcohol (BnOH) as an initiator was examined using FeCia-eHaO and RUCI3H2O. The molecular weight (Mn) increased almost linearly with increasing feed ratio of CL or VL to BnOH. Similar studies were done using BL. The kinetic studies for the polymerization of CL and VL using FeCIa- 6H2O in ratio tmonomer]/[catalyst]=200 were performed. The results for CL polymerization are depicted in Fig. 4. Since BL polymerizations are extremely rapid, such a study could not be done with accuracy. The plots suggest that at first there is an induction period followed by a first-order dependence of rate of polymerization on monomer concentration. Such an induction period for CL polymerizations with non-living characteristics have been reported previously. It has been sufficiently illustrated that the structure of the initiator may influence the strength of the catalyst/initiator interaction. These interactions at the early stages of the reaction are responsible for the formation of the "true" initiating species followed by subsequent ring opening. The catalysts used in these studies are hydrated metal salts. As a result such interactions are feasible. Induction periods using water as an initiator is well documented. The values of the apparent rate constant (/fapp) for CL polymerizations initiated by FeCly 6H2O was found to be 7.38x10"^ min'"' and /Capp for VL polymerizations was estimated to be 5.43x10"^ s'\ The orders of magnitude of /fgpp for CL polymerization indicate that these are much faster than the results known for iron aikoxides. MALDI-MS (Fig .5.) of synthesized low molecular weight oligomers suggest that these polymerizations proceed by the activated monomer mechanism. An intuition to support this is that the polymerization of BL is the fastest followed by VL and then CL. This is against the conventional coordination-insertion mechanism wherein the trend would be the reverse with the polymerization of CL being the fastest due to largest ring strain. Although FGCIJ 6H2O is extremely reactive towards the polymerization of CL, VL, and VL it is relatively sluggish towards the polymerization of LA. Various co¬polymers (Fig. 6.) were derived from these monomers as colourless viscous liquids. This is in sharp contrast to the parent homopolymers which are solids. Bulk polymerizations to produce these copolymers were done up to 150 g scale (Fig. 7.) MECHANISM OF POLYMERIZATION To gain insight into the polymerization characteristics and final composition of the product, it was decided to investigate the polymerization using CL and VL more closely. Low molecular weight oligomers of poly(caprolactone) and poly(valerolactone) were synthesized by stirring these monomers with FeClj 6H2O or RuClffHaO in 15:1 molar ratio under neat conditions at aZ'C. The product was extracted with heptane. In all the cases the residue (after removal of heptane) were analyzed thoroughly using MALDITOF. In case of RuClffH20, the product was analyzed using ^H NMR spectroscopy. Using CL as the substrate for such studies, MALDI-TOF results reveals the major product of the composition HO[CO(CH2)50]nH which is further supported by ^H NIVIR spectroscopy. These observations can be rationalized by considerihg the reaction pathway depicted in Scheme 1. Scheme 1. Reaction pathway for CL polymerization. If E-hydroxycaproic acid (1) is assumed as a polymerization intermediate, it must act as an initiator and possess the capability of initiating polymerization when used along with FeCia-eHaO or RuCia-HaO. Low molecular weight oligomers of poly(caprolactone) were synthesized by stirring CL with RuCly H2O in the presence of 1 as the initiator in 15:1:2 molar ratio^ under neat conditions at 27'C. The work up was done in a similar manner. The ""H NMR spectrum of the crude product had the same characteristics when RuClj H2O was used alone. Polymerizations using CL, FeCl3-6H20 or RUCI3H2O, and 1 in the ratio 200/1/5 were conducted independently at 27X. For FeClj 6H2O, the polymerization time is 6.6 min (M„ = 7.84x10-4 g/mol, MJMn = 1.39) and for RuCijHaO the polymerization time is 10.8 min (Mn = 8.01x10-4 g/mol, MJM^ = 1.42). The polymerization is much faster (Entries 1 and 14 of Table 2), providing sufficient credence to 1 being considered as a true intermediate. Hence, 1 is a suitable initiator towards the synthesis of poly(caprolactone) with -OH end terminal groups. For VL, MALDI-TOF results reveals the major product of the composition HO[CO(CH2)40]„H which is further supported by ^H NMR spectroscopy. The attributes of such a working hypothesis suggests the formation of poly(caprolactone) with -OH end terminal groups if water is used as an initiator. To understand the effect of BnOH, CL or VL along with FeCly6H20 or RuCljHzO and BnOH in the ratio 15:1:2. On a similar basis the reaction mixtures were analyzed using MALDITOF and ^H NMR spectroscopy for reactions using RUCI3H2O. MALDI-TOF results reveal the major product of the composition PhCH20[CO(CH2)50]„H. This is further substantiated by ^H NMR spectroscopy in the case where RUCI3H2O was used. These results are shown in Figs. 8 and 9 respectively. Analysis of Fig. 8 reveals the presence of HO[CO(CH2)50]nH {m/z = 611.5, 725.6, 839.7, 953.8, . . .) in addition to the peaks indicating the required product. Since we are using hydrated salts as initiators, the presence of peaks indicating the role of H2O is obvious. On the basis of Scheme 1, one may consider BnO- C(0)(CH2)50-H (2) as the possible intermediate. For understanding the authenticity of this pathway, bench scale polymerization of CL using FeCly 6H2O or RuCiy H2O in the presence of requisite amounts 2 in the ratio 200/1/5 were performed at 27'C. For FeCly 6H2O, the polymerization time is 15 min (Mn = 9.22x10"'* g/mol,Mw/Mn = 1.40) and for RuClj H2O the polymerization time is 27min (Mn = 6.83x10"* g/mol, MJM„ = 1.37). Similar studies with VL indicated a polymer of composition PhCH20[CO(CH2)40]nH as the major product. ' The results presented here indicate the ring opening polymerizations to proceed by an activated monomer mechanism. An intuition to support this is that the polymerization of BL is the fastest followed by VL and then CL. This is against the conventional coordination-insertion mechanism wherein the trend would be the reverse with the polymerization of CL being the fastest due to largest ring strain. It can be safely concluded that FeCly 6H2O Is a potent initiator towards the ring opening polymerization reactions. Alcohol initiators enhance the tendency of polymerization and produce an alkoxy end terminal functionalized product. The major initiation pathway in the polymerization is understood to be the activated 1 monomer mechanism and can be used towards the synthesis of telechelic polymers copolymers with tunable properties. This polymerization contributes to an economical process employing readily available commercial inorganics as catalysts and does not necessitate solvents. The overall system Is green and eco friendly and environmentally benign since Iron is a natural human constituent and these polymers being biodegradable. The achievement of obtaining good .molecular weights without having to resort to elaborate ligands is a noted feature for our system. WE CLAIM: 1. A process of activated monomer ring opening mode of polymerization for producing a polymer from a corresponding cyclic monomer such as lactide and lactones with an active catalyst to achieve high number average molecular weight (Mn) polymer having desired physical properties, the process characterized in the selected catalyst being simple halldes containing Group 8 metals. 2. The process as claimed In Claim 1 further characterized in the catalyst used along with a mediating agent, which is water. 3. The process as claimed in Claim 1 further characterized in the catalyst used along with a mediating agent, which are nucleophlles such as alcohols. 4. The process as claimed in Claim 1 further characterized in the catalyst used along with mediating agents, which are water and nucleophlles. 5. The process as claimed in Claims 1 to 4, wherein the said selected metals are environmentally benign metals that are constituents in the mammalian anatomy thereby the catalyst residues are potentially harmless. 6. The process as claimed in Claims 1 to 4, wherein the monomer and the metal halide feed ratio is generally 200:1 molar ratio. 7. The process as claimed in Claims 1 to 4, wherein the metal halide catalyst selected is for use with lactone monomers such as e - caprolactone (CL), 6 -vaierolactone (VL) ,p - butyrolactone (BL) and lactide (LA). 8. The process as claimed in Claims 1 to 4, wherein theiatio of the monomer and the halide for CL polymers is 0.5 mL of CL (0.54 g, 4.71 mmol) and 23.6 pmol of metal halide. 9. The process as claimed in Claims 1 to 4, wherein the ratio of the monomer and the halide for VL polymers is 0.25 mL of VL (0.27 g, 2.69 mmol) and 13.5 pmoi of metal halide. 10. The process as claimed in Claims 1 to 4, wherein the ratio of the monomer and the halide for BL polymers is 0.25 mL of BL (0.26 g, 3.06 mmol) and 15.3 pmol of metal halide. 11. The process as claimed in Claims 1 to 4, wherein the molecular weight Mn is further varied by varying the feed ratio of the monomer and the mediating agents. 12. The process as claimed in Claims 1 to 4, wherein polymerization of BL Is faster than the polymerization of VL and the polymerization of VL Is faster than polymerization of CL. 13. The process as claimed in Claims 1 to 4, wherein the process of polymerization comprises of: a. introducing a selected metal halide catalyst Into an enclosed nitrogen atmosphere; b. adding a selected monomer into the enclosure under mixture stirring condition at a given temperature thereby achieving a rise in viscosity of the mixture; c. observing the reduction of monomer until its disappearance; d. quenching by pouring the contents into cold heptane; e. isolating the polymer by filtration; f. drying the filtered polymer; and g. collecting polymer of a constant weight. 14. The process as claimed in Claim 13, wherein the observation of polymerization is done using TLC technique through the disappearance of the monomer. 15. The process as claimed in Claim 13, wherein the catalyst is a metal halide per se. 16. The process as claimed in Claim 13, wherein the catalyst is a metal halide with predetermined amount of nucleophiles such as alcohol. 17. The process as claimed in Claim 13, wherein the catalyst is a metal halide with predetermined amount of nucleophiles such as alcohols and also a predetermined amount of dry toluene' 18. The process as claimed in Claim 13, wherein FeCia is selected as a catalyst comprising of additional steps of performing of ste|a>(a)and (b) below prior to step (a) of claim 13 and performing step (c) below alongwith step (b) of claim 13 wherein the steps (a), (b) and (c) is as follows : a. selecting anhydrous FeCIa; b. contaminating the anhydrous FeCia with a known stoichiometric of water to form metal halide catalyst; and c. polymerizing a selected monomer with the catalyst under rapid stirring at a given temperature, characterized in the selection of the catalyst and the ratio of the monomer and metal halide catalyst. 19. A process of activated monomer ring opening mode of polymerization for producing a copolymer from corresponding plurality of cyclic monomers such as lactide and lactones with an active catalyst to achieve high number average molecular weight (Mn) polymers having desired physical properties, the process characterized in the selected catalyst being simple halides containing Group 8 metals. 20. The process as claimed in Claim 19 further characterized in the catalyst used along with a mediating agent, which is water. 21. The process as claimed in Claim 19 further characterized in the catalyst used along with a mediating agent, which are nucieophrle& such as alcohols. 22. The process as claimed in Claim 19 further characterized in the catalyst used along with mediating agents, which are water and nucleophiles. 23. The process as claimed in Claims 19 to 22, wherein the said metals are environmentally benign metals that are constituents in the mammalian anatomy thereby the catalyst residues are potentially harmless. 24. The process as claimed in Claims 19 to 22, wherein the mixture of monomers and the metal halide feed ratio selected may be 200:1,100:1, or 50:1 molar ratio. 25. The process as claimed in Claims 19 to 22, wherein the metal halide catalyst selected is for a mixture of some or all of lactone monomers such as £ -caprolactone (CL), 5 - valerolactone (VL) ,p - butyrolactone (BL) and lactide (LA). 26. The process as claimed in Claims 19 to 22, wherein the molecular weight IVIn is varied by varying the feed ratio of the mixture of monomers and the mediating agents. 27. The process as claimed in Claims 19 to 22, wherein the process of polymerization comprises of: a. introducing a selected metal halide catalyst into an enclosed nitrogen atmosphere; b. adding a selected plurality of said monomers into the enclosure under mixture stirring condition at a given temperature thereby achieving a rise in viscosity of the mixture; c. observing the reduction of monomers until their disappearance; d. quenching by pouring the contents into cold heptane; e. isolating the copolymer by filtration; f. drying the filtered copolymer; and * g. collecting copolymer of a constant weight. 28. The process as claimed in Claim 28, wherein the observation of polymerization is done using TLC technique through the disappearance of the monomers. 29. The process as claimed in Claim 28, wherein the catalyst is metal halide per se. 30. The process as claimed in Claim 28, wherein the catalyst is metal halide with predetermined amount of nucleophiles such as alcohol. 31. The process as claimed in Claim 28, wherein the catalyst is metal halide with predetermined amount of nucleophiles such as alcohol and also a predetermined amount of dry toluene. 32. The process as claimed In Claims 28, wherein FeCIs is selected as a catalyst comprising of additional steps of performing of step (a) and (b) below prior to step (a) of claim 28 and performing step (c) below alongwith step (b) of claim 28 wherein the steps (a), (b) and (c) is as follows : a. selecting anhydrous FeCis; b. contaminating the anhydrous FeCis with a known stoichiometric of water to form metal halide catalyst; and c. polymerizing a mixture of selected monomers with the catalyst under rapid stirring at a given temperature, characterized in the selection of the catalyst and the ratio of the mixture of monomers and metal halide catalyst.

Documents:

3099-CHE-2009 AMENDED CLAIMS 23-09-2014.pdf

3099-CHE-2009 FORM-3 23-09-2014.pdf

3099-CHE-2009 FORM-5 23-09-2014.pdf

3099-CHE-2009 AMENDED PAGES OF SPECIFICATION 23-09-2014.pdf

3099-CHE-2009 EXAMINATION REPORT REPLY RECIEVED 23-09-2014.pdf

3099-che-2009 abstract 15-12-2009.pdf

3099-che-2009 claims 15-12-2009.pdf

3099-che-2009 correspondence-others 15-12-2009.pdf

3099-che-2009 description (complete) 15-12-2009.pdf

3099-che-2009 drawings 15-12-2009.pdf

3099-che-2009 form-1 15-12-2009.pdf

3099-CHE-2009 FORM-18 21-01-2010.pdf

3099-che-2009 form-2 15-12-2009.pdf

3099-che-2009 form-3 15-12-2009.pdf

3099-che-2009 form-5 15-12-2009.pdf

3099-che-2009 power of attorney 15-12-2009.pdf