Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1995-02-03
1997-04-08
Lipman, Bernard
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525296, 5253338, 525353, 525366, 525387, 525398, 525401, 525420, 525426, 525437, 525445, 525452, 525455, 525472, C08F 808
Patent
active
056188870
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the functionalisation of polymers. More particularly it relates to the treatment of polymers which do not possess groups normally considered readily reactive. It also relates to the coupling of so-treated polymers which other materials, for example, monomers, polymers, bioactive materials and dyes.
Conventional procedures for activating the surface of, for example, polypropylene include the action of high energy radiation, glow and corona discharges, photoinitiation with the use of a sensitiser such as benzophenone, reaction with ozone, and surface flaming. Some of these procedures have the disadvantage of severely degrading the polymer and the use of non-aqueous media may be necessary.
Early work with polypropylene was aimed at introducing hydroperoxides; thus in DE-A- 1595 808 and GB-A- 1086108 and by Jabloner and Mommar (J. Polymer Sci. A-1, 1972, 10, (763-778)) it was claimed that a cation surfactant and potassium peroxysulphate could be used to achieve wetting and initiate oxidation of polypropylene powder as slurry. The reaction was carried out in the presence of oxygen (e.g. at 30 p.s.i.), at 100.degree. C. Critical importance was attached to the presence of the cationic surfactant and it was stated that an anionic surfactant did not lead to significant hydroperoxidation. Graft copolymerization was subsequently carried out by addition of a redox system (e.g. ferric salt and benzion) and a vinyl monomer at 65.degree. C.
In many other examples the polymer (polypropylene), initiator (e.g. peroxysulphate) and monomer were reacted together. This procedure led to a high yield of homopolymer. Any graft copolymer was probably formed by chain transfer involving initial or propagating radicals and the polymer.
It has now been found possible to functionalise many polymers by an inexpensive and simple method. It has been found possible to provide such a method which takes a relatively short time and can be effected in aqueous media.
According to the present invention there is provided a method of functionalisating of a polymer, which method comprises reacting the polymer in an aqueous medium with an oxidising agent to produce oxygen-centered radicals which are responsible for introducing hydroxyl groups into the polymer, the reaction being carried out in the absence of (a) any additive which is preferentially oxidised or is reactive towards the radicals produced by the oxidising agent, (b) added oxygen and (c) a cationic surfactant.
According to a further aspect of the present invention there is provided a method for the functionalisation of a polymer, which method consists essentially of reacting the polymer with a suitable oxidising agent in an aquous medium.
A suitable oxidising agent is an oxidising agent capable of producing oxygen-centered radicals (i.e. the free radical is on the oxygen atom) in aqueous media. Under appropriate conditions such radicals can be responsible for introducing hydroxyl groups into the polymer, thus producing a functionalisation process. It is important to note that during the oxidation process no additives with readily extractable hydrogen atoms are present.
The oxidising agent usually used in the method of the present invention is a peroxy salt of a metal, preferably a peroxy-disulphate or monosulphate. We have examined the effectiveness of several peroxidants for the hydroxylation of polystyrene and found the following order: ##STR1## The last compound in the series, that is peracetic acid, has been found to be only very weakly active under the test conditions used.
The present invention will be further described for the sake of convenience with reference to (but in no manner limited to) the use of peroxysulphates as the oxidising agents.
The decomposition of the peroxy moiety may be considered to be in accordance with the equation: ##STR2##
The peroxysulphate may be an alkali metal peroxysulphate, preferably potassium peroxysulphate. A particularly useful potassium compound is a triple salt having the composition 2KHSO.sub.5.KHSO.sub.4.K.sub.
REFERENCES:
Jabloner et al., "Heterogeneous Grafting of Polypropylene and Physical Properties of Graft Blends", Journ. Poly. Sci., vol. 10, (1972), pp. 763-778.
Kolthoff et al., "The Chemistry of Persulfate. I. The Kinetics and Mechanism of the Decomposition of the Persulfate Ion in Aqueous Medium.sup.1 ", Polymer Sci., vol. 73, No. 1, (1946), pp. 3055-3059.
Mino et al., "A New Method for the Preparation of Graft Copolymers. Polymerization Initiated by Ceric Ion Redox Systems", Journ. of Poly. Sci., vol. XXXI, Issue No. 122, (1958), pp. 242-243.
William A. Szabo, "Chlorosulfonyl Isocyanate, Silver Anniversary of a Lively Heterocumulene", Aldrichimica Acta, vol. 10, No. 2, pp. 23-29.
Al-Lamee Kadem G.
Bamford Clement H.
Lipman Bernard
The University of Liverpool
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