Title of Invention

"A PROCESS FOR THE PREPARATION OF HYPERBRANCHED POLYMERS OF DIISOPROPHENYLBEZENE OR DIVINYLBENZENE OR ITS COPOLYMERS"

Abstract A process for the preparation of hyperbranched polymers of diisopropenylbenzene or divinyl/benzene or its copolymers by mixing an initiator with diisopropenylbenzene or divinylbenzene monomer in a mole ratio of 1:1 to 1:0.4 in less than 2 seconds at 30°C to -40°C in an organic solvent, cooling the said mixture to -40°C to obtain a solution of hyperbranched polymer, optionally adding co-monomer equal to or higher than initiator moles periodically, terminating the said reaction with a small amount of degassed methanol and separating the hyperbranched polymer by conventional precipitation using a non-solvent.
Full Text This invention relates to a process for the preparation of hyperbranched polymers and copolymers. More particularly the present "invention relates to a process for the production of hyperbranched polymers from divinylbenzene or 1,3-diisopropenylbenzene in presence or in absence of a co-monomer such as styrene, 1,1-diphenylethylene with broad molecular weight distribution using anionic initiator.
Physical properties of polymers mainly depend on their chemical composition and architectural features. The physical properties can be tailored by manipulation of the polymer's main-chain topology (US Patent 5587441 (1996), Science, 263, 1710, 1994, ACS Symp. Scr. 285, 175, 1985 and J. Am. Chcm. Soc., 117, 6414, 1995). Branching in a linear polymer exerts tremendous influence on chemical, physical, mechanical and Theological properties.
Regular, well-defined branching in a polymer synthesis produces a globular shape three-dimensional topology called dendrimers (J. Org. Chem., 50, 2003, 1985, Angew. Chem., 102, 119, 1990 and Macromolecules, 24, 5893, 1991). However, dendrimers are very difficult to produce as the synthesis involves multi-step reactions. It is also known that a less well-defined hyperbranched polymer can be obtained from condensation of

AB2 type monomers (J. Am. Chem. Soc., 74, 2718, 1952). Recently, Frechet and co-workers demonstrated a novel method for the synthesis of hyperbranched polymers using vinyl monomer which has a dormant functional group with the potential of initiating vinyl groups when activated by an external stimulus (US Patent 5587446 (1996), 5635571 (1997), 5663260 (1997), Science, 269, 1080, 1995 and J. Am. Chem. Soc., 117, 10763, 1995). Upon activation of the dormant group in such a vinyl monomer, it initiates

intermolecularly and produces hypcrbranched polymer. As the intermolecular reaction of vinyl monomer containing initiating group resembles polycondensation, the process is called as self-condensing vinyl polymerization (SCVP).
Several vinyl monomers such as p-(chloromethyl)styrene (Science, 269, 1080, 1995), 2-((2-bromopropionyl)oxy)ethyl acrylate (US Patent 5763548 (1998), and Macromolecules, 30, 7034, 1995), are used for SCVP. Depending on the nature of monomer, suitable polymerization methods have been adopted for SCVP, i.e., cationic (Science, 269, 1080, 1995), radical (J. Am. Chem. Soc., 117, 10763, 1995), atom transfer radical (Macromolecules, 30, 7034, 1997), and group transfer polymerization (GTP) (Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.), 38, 498, 1997 and Macrmol. Rapid Commun., 18, 865, 1997). However, anionic polymerization method has not been yet applied for SCVP. It is possible to synthesis hyperbranched polymer using anionic initiators and divinylbenzene monomers under appropriate condition. Hyperbranched polymers are expected to have non-Newtonian flow in melt as well as in solution viscosity and hence low viscosities can be achieved for a very high molecular weight. Hyperbranched polymeric materials will have important role to play in industry as they are cost effective compare to regular dendritic polymers.
The main object of the present invention is therefore to provide a process for the preparation of hyperbranched polymers and copolymers using divinylbenzene monomers with anionic initiators.
Another objective is to produce hyperbranched copolymers using divinylbenzene monomers with other non-acrylic comonomers. Yet another objective is to enable the

production of polymers and copolymers with a- wide range of molecular weight with broad molecular weight distribution with polydispersities in the range of 2 to 50.
Still another objective is to enable the production of hyper-brached polymers or
copolymers consisting of chain end functionality, which can be used for further post reactions.
Accordingly, the present invention provides a process for the preparation of hyperbranched polymers and copolymers which comprises mixing an equimolar amount of initiator and diisopropenylbenzene or divinylbenzene monomer in less than 2 seconds at 30 °C to -40 °C in an organic solvent, cooling the said mixture to -40 °C to obtain a solution of hyperbranched polymer, optionally adding co-monomer equal to or higher than initiator moles periodically, terminating the said polymer with a small amount of degassed methanol and separating the hyperbranched polymer by conventional precipitation using a non-solvent.
In one of the embodiments of the present invention, the initiator used may be of general formula (I), in the drawing accompanying the specification, where R1 = linear or branched alkyl group having one to six carbon atoms, R2 = hydrogen atom or phenyl or alkyl group having one to six carbon atoms, R3 = hydrogen atom or phenyl or an ester group, and M+ is an alkali or alkaline earth metal such as n-, secondary, or tertiary-butyllithum and 1,1-diphenylhexyllithium.
In another embodiment the monomer used may be such as 1,3-divinylbenzene, 1,4-divinylbenzene, commercial mixture of 1,3 and 1,4-divinylbenzene (with 35% ethylvinylbenzene) (DVB) and 1,3-diisopropenylbenzene (DIPB).

In yet another embodiment, the mole ratio of initiator to monomer can vary from 1:1 to 1:0.4 preferrably 1:1.
In still another embodiment the solvent used for the synthesis of hyper branched polymer may be selected from tetrahydrofuran (THF), tetrahydropyran (THP), or hydrocarbon such as benzene, toluene, ethylbenzene, xylene and cyclohexane preferably tetrahydrofuran.
In yet another embodiment the non-solvent used for the precipitation may be such as methanol, methanol-water (8:2 v/v) mixture, n-hexane and petroleum ether.
In still another embodiment the comonomer used may be such as styrene or alpha-methylstyrene, isoprene, butadiene, 1,1-diphenylethylene, alkyl (meth)acrylates, and other (alkyl) acrylates.
The process of the present invention is described hereinbelow with examples, which are illustrative only and should not be construed to limit the scope of the invention, in any manner.
Example 1
This example illustrates the synthesis of hyperbranched polymer using divinlybenzene (DVB) and n-butyllithium in THF at -40 °C
Into a dry 250 mL round bottom flask equipped with magnetic needle, nitrogen/vacuum three-way adapter with rubber septum, was added 30 mL dry tetrahydrofuran. 0.4 mL, 2.26x10"3 moles of divinylbenzene (35 % ethylstyrene) was added into the polymerization flask and the temperature was brought to -40 °C. Then, 2.4 mL, 2.287x10'3 moles of n-butyllithium (0.953M) was added into the monomer solution very fast (
solution turned into dark red colour and no gelation was observed throughout the reaction. The reaction was terminated after 10 min with 2 mL of degassed methanol. The polymer was recovered by precipitation in excess "methanol and dried at 80 °C for 12 h under vacuum giving 0.46 gm of hyperbranched polyDVB (98 % yield).
Gel permeation chromatography equipped with 100Å, 500 Å, 103 Å, 104 Å and one linear µ-ultrastyragcl columns showed that the polymer had Mn,cpc = 14,990 g/mol, MW.GPC = 1,11,500 g/mol and Mw/Mn = 7.4 with respect to PMMA calibration standards. Intrinsic visocity of the polymer measured in chloroform at 30 °C is 0.77 dL/g.
Example 2
This example illustrates the synthesis of hyperbranched polymer using 1,3-diisopropenylbenzene (DIPB) and n-butyllithium in THF at -40 °C
Into a dry 250 mL round bottom flask equipped with magnetic needle, nitrogen/vacuum three-way adapter with rubber septum, was added 50 mL dry tetrahydrofuran. 1.0 mL, 5.84xlO-3 moles of diisopropenylbenzene was added into the polymerization flask. Then, 4.2 mL, 5.84xlO-3 moles of n-butyllithium (1.39M) was added into the monomer solution at 30 °C very fast (
Gel permeation chromatography equipped with 100Å, 500 Å, 103 Å, 104 Å and one linear µ-ultrastyragel columns showed that the polymer had Mn,cpc = 360 g/mol, MW,GPC = 1500 g/mol and Mw/Mn = 4.16 with respect to PMMA calibration standards.
Example 3
This example illustrates the synthesis of hyperbranched copolymer using 1,3-diisopropenylbenzene (DIPB), styrene and n-butyllithium in THF at -40 °C
Into a dry 250 mL round bottom flask equipped with magnetic needle, nitrogen/vacuum three-way adapter with rubber septum, was added 60 mL dry tetrahydrofuran. 1.0 mL, 5.84xlO"3 moles of diisopropenylbenzene was added into the polymerization flask. Then, 4.2 mL, 5.84xlO-3 moles of n-butyllithium (1.39M) was added into the monomer solution at 30 °C very fast ( Gel permeation chromatography equipped with lOOÅ, 500 Å, 103Å, 104 Å and one linear µ.-ultrastyragel columns showed that the polymer had Mn,Gpc = 4500 g/mol, Mw,Gpc = 21180 g/mol and Mw/Mn = 2.70 with respect to PMMA calibration standards.

Example 4
This example illustrates the synthesis of loosely hyperbranched poly(diisopropenylbenzene-co-styrene) using 1,3-diisopropenylbenzene, styrene and n-butyllithium in THF at -40 °C
Into a dry 250 mL round bottom flask equipped with magnetic needle, nitrogen/vacuum three-way adapter with rubber septum, was added 10 mL dry tetrahydrofuran. 0.5 mL, 2.92xlO-3 moles of diisopropenylbenzene was added into the polymerization flask. Then, 2.1 mL, 2.92x10-3 moles of n-butyllithium (1.39M) was added into the monomer solution at 30 °C very fast ( Gel permeation chromatography equipped with 100Å, 500Å, 103 Å, 104 Å and one linear µ-ultrastyragel columns showed that the polymer had Mn,cpc = 26100 g/mol, MWtcpc = 80982 g/mol and Mw/Mn = 3.10 with respect to PMMA calibration standards.

Example 5
This example illustrates the synthesis of star (poly methylmethacrylate) using hyperbranched oligo (diisopropenylbenzene-co-styrene) core in THF at -78 °C
Into a dry 250 mL round bottom flask equipped with magnetic needle, nitrogen/vacuum three-way adapter with rubber septum, was added 125 mL dry tetrahydrofuran. 2.5 mL THF containing 250 mg of LiClO4 and 0.4 mL, 2.33x10-3 moles of diisopropenylbenzene was added into the polymerization flask. Then, 1.34 mL, 2.34xlO"3 moles of n-butyllithium (1.75M) was added into the monomer solution at 30 °C. The reaction solution turned into dark red color and no gelation was observed. The reaction was stirred for 10 min and then, the reaction temperature was brought down to -78 °C. After 15 min, 0.28 ml of styrene was added to form hyperbranched oligoDIPB. To this solution, 10 mL, 9.36 grams of methyl methacrylate was added. The reaction was terminated after 20 min with 1 mL of degassed methanol. The polymer was recovered by precipitation in excess methanol and dried at 80 °C for 12 h under vacuum giving 10 grams of star (poly methylmethacrylate) with hyperbranched copoly (DIPB-co-styrene) core moiety. (100 % yield).
Gel permeation chromatography equipped with lOOA, 500 Å, 103 Å, 104 Å and one linear µ-ultrastyragel columns showed that the polymer had Mn,cpc = 31000 g/mol, MW-GPC = 46870 g/mol and Mw/Mn = 1.5 with respect to PMMA calibration standards.

Example 6
This example illustrates the procedure for the synthesis of hyperbranched copolymer consisting of 1,3-diisopropenylbenzene and styrene as repeat units in THF at -40 °C.
The polymerization was carried out under pure nitrogen atmosphere. To a 250 mL flame dried round bottomed flask connected with an ampoule containing 4.2 mL (5.84 x 10-3 moles) of 0.139 M nBuLi in cyclohexane, was added 150 mL of tetrahydrofuran. 1,3-diisopropenylbenzene, 1 mL, (5.84 x 10-3 moles) was added into the polymerization flask and nBuLi was then added into the monomer solution very fast (
(98 % yield) by this procedure are all soluble in toluene, tetrahydrofuran, and chlorinated solvents. The polymers were characterized for their molecular weights using Gel permeation chromatography equipped with lOOA, 500 Å, 103 Å, 104 Å and one linear µ-ultrastyragel columns. The molecular weights determined with respect to PMMA calibration standards are given in the Table 1.
Table. 1. Results of the hyperbranched poly (diisopropenylbenzene-co-styrene) formed at different generations using styrene ([styrene]/[Li+] = 1) as promoter at -40 °C in THF

(Table Removed)
Example 7
This example illustrates the synthesis of hyperbranched polymer using 1,3-diisopropenylbenzene (DIPB), styrene and 1,1-diphenylhexyllithium in THF at -40 °C
Into a dry 250 mL round bottom flask equipped with magnetic needle, nitrogen/vacuum three-way adapter with rubber septum, was added 50 mL dry tetrahydrofuran. 1.0 mL, 5.84xlO-3 moles of diisopropenylbenzene was added into the polymerization flask. Then, 3.4 mL, 5.84xlO-3 moles of 1,1-diphenylhexyllithium (1.4M)

was added into the monomer solution at 30 °C. The reaction solution turned into dark red colour and no gelation was observed. The reaction was stirred for 15 min and then, the reaction temperature was brought down to —40 °C. After 15 min, 0.7 ml, 6.1xlO-3 moles of styrene was added to enhance self-condensation of the preformed hyperbranched oligoDIPB. The reaction was terminated with 2 mL of degassed methanol after 20 min. The polymer was recovered by precipitation in excess methanol and dried at 60 °C for 12 h under vacuum giving 2 gm of hyperbranched copoly (DIPB-co-styrene) (-100 % yield).
Gel permeation chromatography equipped with 100Å, 500Å, 103 Å, 104Å and one linear µ-ultrastyragel columns showed that the polymer had Mn,Gpc = 8700 g/mol, MW,GPC = 21680 g/mol and Mw/Mn = 2.49 with respect to PMMA calibration standards.
The present invention has following advantages:
1) Hyper branched polymers can be synthesized using commerically available
divinylbenzene monomer.
2) The living ends of the hyperbranched polymers can be either used for
functionalization or used as multifunctional initiator for the synthesis of hyper-star
polymer.





We claim:
1. A process for the preparation of hyperbranched polymers and copolymers which,.
comprises mixing an equimolar amount of jnitiatprlmd diisopropenylbenzene or

divinylbenzene monomer in less than 2 seconds at 30 °C to -40 °C in an organic;

solvent) cooling the said mixture to -40 °C to obtain, a solution of hyperbranched
polymer, optionally adding equal to or higher than initiator moles
periodically terminating the said polymer with a small amount of degassed

methanol and separating the hyperbranched polymer by conventional precipitation])
using a non-solvent.)
2. A process as claimed in claim 1 wherein, the initiator has general formula (I), in
the drawing accompanying the specification, where R1 = linear or branched alkyl
group having one to six carbon atoms, R2 = hydrogen atom or phenyl or alkyl
group having one to six carbon atoms, R3, = hydrogen atom or phenyl or an ester
group, and M+ is an ^kali or alkaline earth] metal such as n-, secondary, or
tertiary-butyllithum and 1,1-diphenylhexyllithium.
3. A process as claimed in claims 1 to 2 wherein the monomer used is such as 1,3-
divinylbenzene, 1,4-divinylbenzene, commercial mixture of 1,3 and 1,4-
divinylbenzene (with 35% cthylvinylbenzenc) and 1,3-diisopropenylbenzene.
4. A process as claimed in claims 1 to 3 wherein the mole ratio of initiator to
monomer vary from 1:1 to 1:0.4 preferrably 1:1.
5. A process as claimed in claims 1 to 4 wherein the solvent used for the preparation
of hyperbranched polymer is such as tetrahydrofuran (THF), tetrahydropyran



(THP), or hydrocarbon such as benzene, toluene, ethylbenzene, xylene and
cyclohexane preferably tetrahyclrofuran.
A process as claimed in claims 1 to 5 wherein the comonomer, if necessary, may
be styrene or alpha-methylstyrene, isoprene, butadiene, 1,1-diphenyethylene,
alkyl (meth)acrylates, and other (alkyl) acrylates.
A process for the preparation of hypcrbranchcd polymer and copolymer as fully
described hereinbefore with reference to the examples contained therein.



Documents:

1151-del-1999-abstract.pdf

1151-DEL-1999-Claims.pdf

1151-del-1999-correspondence-others.pdf

1151-del-1999-correspondence-po.pdf

1151-del-1999-description (complete).pdf

1151-del-1999-drawings.pdf

1151-del-1999-form-1.pdf

1151-del-1999-form-19.pdf

1151-DEL-1999-Form-2.pdf


Patent Number 215492
Indian Patent Application Number 1151/DEL/1999
PG Journal Number 11/2008
Publication Date 14-Mar-2008
Grant Date 27-Feb-2008
Date of Filing 26-Aug-1999
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 DURAIRAJ BAKARAN NATIONAL CHEMICAL LABORATORY, PUNE-411 008, INDIA.
PCT International Classification Number C08L 25/04
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA