Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From heterocyclic reactant containing as ring atoms oxygen,...
Reexamination Certificate
2002-01-25
2003-09-09
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From heterocyclic reactant containing as ring atoms oxygen,...
C528S403000, C528S408000, C528S409000, C528S420000, C528S486000
Reexamination Certificate
active
06617418
ABSTRACT:
The present invention refers to a hyperbranched dendritic polyether obtainable in a process comprising the step of thermally initiated cationic ring-opening of at least one oxetane having at least two reactive groups of which at least one is an oxetane group. In a further aspect, the present invention refers to a process for the manufacture of said hyperbranched dendritic polyether.
Macromolecular architecture has received increasing attention during the last decade. The interest is governed by the realisation that new and/or improved material properties can be obtained by altering the architecture of the polymers. Especially dendritic polymers, that is dendrimers and hyperbranched polymers, have received considerable attention in this context. The most characteristic features of dendritic polymers in contrast to linear polymers or ordinarily and randomly branched polymers are the absence of entanglements and the low viscosity in bulk.
Dendritic polymers are based on for instance AB
x
monomers and are highly branched macromolecules with a multitude of end-groups. Dendrimers are monodisperse, exact structures where all branch points are utilised. Due to their well defined structure dendrimers are tedious and often expensive to synthesise. Hyperbranched polymers are polydisperse and some of the AB
x
monomers are incorporated in a linear fashion, resulting in a less well defined architecture. Hyperbranched polymers are less complicated to synthesise and, therefore, less expensive which makes them more attractive than dendrimers for large-scale applications.
Conceptually, condensation monomers of AB
x
type are the easiest to identify and a wide variety of such monomers have also been demonstrated to yield hyperbranched and dendritic polymers. Various dendritic, including dendrimers, polyesters and processes for production thereof are disclosed in the Swedish patents 468 771 and 503 342. Polyether dendrimers produced using complex and expensive protective chemistry are discussed but not further evaluated or prepared in the European patent 115 771. More recently, vinyl monomers, bearing both an initiating and a propagating function has been utilised to result in hyperbranched or dendritic polymers, both via cationic and free radical procedures—J. M. J. Fréchet et al.,
Science,
269, 1080 (1995), C. J. Hawker, et al.,
J. Am. Chem. Soc.
117, 10763 (1995) and S. G. Gaynor et al.,
Macromolecules
29, 1979 (1996).
So far no successful ring-opening polymerisation resulting in hyperbranched dendritic polyethers, including dendrimers, has been reported. The ring-opening polymerisation of 3-hydroxymethyl-3-methyl oxetane under basic conditions was reported by Y. H. Kim in
J. Polym. Sci. Part A: Polym. Chem.,
36, 1685 (1998). However, only a low molar mass polyether was obtained.
The present invention provides quite unexpectedly hyperbranched dendritic polyethers by means of cationic ring-opening polymerisation of at least one oxetane. The present invention accordingly provides hyperbranched dendritic polyethers readily synthesised in bulk. The hyperbranched dendritic polyether of the present invention has like most of the well-known hyperbranched dendritic polyesters terminal hydroxyl groups and can accordingly like said polyesters be further processed to yield hyperbranched dendritic polymers having desired end-groups and tailor-made final properties. Hyperbranched dendritic polyethers are, as polyethers normally are, less susceptible to hydrolysis and have a slightly more flexible main chain than corresponding polyesters, which properties imply utilisation, and pending improved properties, in application areas wherein esters are less suitable. A further advantage is that the hyperbranched polyether of the present invention in most cases easily can be purified by simple precipitation.
The hyperbranched dendritic polyether of the present invention is accordingly obtainable in a process comprising the step of thermally initiated cationic ring-opening polymerisation of at least one oxetane having at least two reactive groups of which at least one is an oxetane group. The thermally initiated ring-opening polymerisation is performed using an effective amount of at least one initiator, such as an onium salt, a Lewis acid and/or a Brønsted acid. Terminal groups or functions in obtained hyperbranched dendritic polyether are normally and substantially hydroxyl groups. The hyperbranched dendritic polyether can also optionally comprise one or more other monomeric or polymeric molecules. The hyperbranched dendritic polyether can furthermore and optionally be a further processed polymer, such as further chain extended, chain terminated and/or functionalised.
The hyperbranched dendritic polyether of the present invention is as disclosed above obtainable in a process comprising said oxetane, whereby the oxetane for instance may be part of a reaction mixture comprising said oxetane in an amount, such as at least 1%, sufficient to provide branching. The oxetane may have two or more oxetane groups or one or more oxetane groups and one or more hydroxyl groups and similar or other suitable combinations of groups and functions. A reaction mixture comprising said oxetane can in addition thereto comprise at least one additional oxetane having at least one oxetane group and optionally one or more other reactive groups and/or at least one alcohol, epoxide, anhydride, tetrahydrofuran and/or lactone.
Said at least one oxetane having said at least two reactive groups is in preferred embodiments of the present invention a compound of the general formula
wherein R
1
is alkyl, alkyloxy, alkyloxyalkyl, aryloxyalkyl, hydroxyalkyl, hydroxyalkyloxy, aryl, aryloxy, hydroxyaryl or hydroxyaryloxy, R
2
is hydroxyalkyl, hydroxyalkyloxy, hydroxyaryl or hydroxyaryloxy, and wherein each R
3
independently is hydrogen, alkyl, alkyloxy, alkyloxyalkyl, aryloxyalkyl, hydroxyalkyl, hydroxyalkyloxy, aryl, aryloxy, hydroxyaryl or hydroxyaryloxy. Said alkyl is preferably linear or branched alkanyl or alkenyl having 1 to 24, such as 3 to 24, 1 to 12, 4 to 12 or 2 to 8, carbon atoms. The oxetane is in especially preferred embodiments an oxetane of a 2-alkyl-2-hydroxyalkyl-1,3-propanediol, a 2,2-di(hydroxyalkyl)-1,3-propanediol, a 2-alkyl-2-hydroxyalkyloxy-1,3-propanediol, a 2,2-di(hydroxyalkyloxy)-1,3-propanediol or a dimer, trimer or polymer of said 1,3-propanediol, wherein said alkyl independently and preferably is linear or branched alkanyl or alkenyl having 3 to 24, such as 4 to 12, carbon atoms. The most preferred embodiments of the present invention comprises an oxetane of a tri and polyalcohol, such as trimethylolethane, trimethylolpropane, pentaerythritol, ditrimethylolethane, ditrimethylolpropane or dipentaerythritol.
The initiator is preferably at least one onium salt, such as a sulphonium, oxonium and/or iodonium salt, and can be exemplified by a compound of structural formula
wherein X is a halogen containing group. The initiator according to said formula can be exemplified by benzyltetramethylenesulphonium hexafluoroantimonate (X
−
is SbF
6
−
), benzyltetramethylenesulphonium hexafluorophosphate and benzyltetramethylenesulphonium trifluoromethanesulphonate. The initiation proceeds in such a case by a reversible generation of the benzyl cation which is stabilised by the non-nucleophilic anion. The benzyl cation is responsible for the initiation of the polymerisation by addition to the nucleophilic oxetane ring.
Further initiators can be found among Lewis acids, such as BF
3
, AlCl
3
, FeCl
3
and/or SnCl
4
, and Brønsted acids such as naphthalene sulphonic acid, para-toluene sulphonic acid, methane sulphonic acid, trifluoromethane sulphonic acid, trifluoroacetic acid, sulphuric acid and/or phosphoric acid.
Embodiments of the hyperbranched dendritic polyether of the present invention include species being further processed, whereby at least one spacing or branching monomeric or polymeric chain extender is added to at least one terminal hydroxyl group in said polyether. Spacing or branching chain extenders
Hult Anders
Magnusson Helen
Malmstrom Eva
Rehnberg Nicola
Perstorp AB
Stevens Davis Miller & Mosher L.L.P.
Truong Duc
LandOfFree
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