Polymers with anti-microbial properties

Details Polymers with anti-microbial properties Polymers with anti-microbial properties

1999-07-16

2001-02-27

Pezzuto, Helen L. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S320000, C526S328500, C526S329600, C526S332000

Reexamination Certificate

active

06194530

ABSTRACT:

The invention relates to polymers with antimicrobial properties. The polymers according to the invention comprise vinyl-type polymerizable monomers which are known themselves as well as monomers in which at least one long-chain alkyl residue is bonded to a quaternary ammonium group, which in turn is bonded with a vinyl function via a hydrophilic spacer and if applicable a linking unit.
PRIOR ART
European Patent Application 0641805 A1 describes polymers with antimicrobial (biophobic) properties. The polymers comprise ethylene-type unsaturated monomers containing some antimicrobial phenolic agents bonded covalently via side groups.
By analogy with polymers, the phenolic agents are bonded to repeat units having functional groups that can react with amino or hydroxyl groups. Examples of reactive residues are hydroxy, hydroxyalkyl, dialkylaminoalkyl or haloalkyl groups. The phenolic residues of the monomers having biocidal function are therefore bonded with the polymer matrix via relatively short, hydrophobic spacers.
The abstract of Japanese Patent 62-05936 (Chemical Abstracts, 107, 41977v) describes antifungal and antibacterial agents. These have a (meth)acryl residue, to which there is bonded a fluorinated aromatic group via an ethylene glycol, propylene glycol or hydroxypropylene group containing 1 to 4 units. The monomers, in the form of a polyvinyl chloride paste, are used, for example, as antimicrobial coating on paper. Use in polymers is not mentioned.
Nazarova et al. (Chemical Abstracts 122: 230183d: Khim.-Farm. Zh. (1993), 27 (2), 30-3) describe biophobic polymers of N-(2-hydroxypropyl)methacrylamide containing bound chloramphenicol.
Therein higher activity is observed in vivo when the chloramphenicol is additionally bonded to the polymer and cleaved from the polymer via a glycine-leucine-glycine spacer. The authors suspect particularly good action toward intracellular microorganisms. Obviously the ease of cleavage of the chloramphenicol from the polymer by enzymatic hydrolysis of the peptide bond is decisive for the good in vivo effect.
The incorporation of a bactericidal monomer for dental applications is described in J. Dent. Rs. 73(8), 1437-1443 (1994). An antimicrobial effect is observed without release of the active species, although it is not clear whether the effectiveness is derived from a bactericidal or biophobic (antiadhesion) property. The pyridinium compound used is bonded to the polymer skeleton via a hydrophobic spacer (long-chain alkyl residue).
OBJECT AND ACHIEVEMENT
The object of the invention is to provide copolymers which are obtained by copolymerization of monomers having antimicrobial effect and which are suitable for making coatings or shaped articles whose surfaces have biocidal or biophobic properties without releasing toxic compounds. In this way it is intended that subsequent addition of microbiologically active molecules to surfaces by analogy with polymers can be avoided. Another goal is to discover a class of active substances as an alternative to the phenolic compounds, among other purposes to prevent selection of resistant strains by variation or combination of active substances and to close gaps in activity.
It has been found that polymers of the following structure have good antimicrobial properties. The polymers comprise
a) 99 to 40 wt % of nonfunctional vinyl-type polymerizable monomers and
b) 1 to 60 wt % of functional vinyl-type polymerizable monomers of general formula (I)
[V-A
y
-HSp]
m
-N
⊕
(R
1
)
4−(m+t)
-(R
2
)
t
.X
−
  (I)
 where
V=vinyl, (meth)acroyl, allyl or styryl,
A=a linking unit which is present if necessary, which can be alkyl, aryl, arylalkyl or hydroxyalkyl, and which can also be interrupted by heteroatoms, for example by heteroatoms in urethane, carbonate, ester, amide or ether groups, where y=0 or 1,
HSp=a hydrophilic spacer of general formula
—(O—CH
2
—CH
2
)
r
—  (i)
and/or
—(O—CH
2
—CH(CH
3
))
s
  (ii)
where r=0 to 40, s=0 to 40 and r+s=2 to 40, as well as
m=1, 2 or 3 and
R
1
=CH
3
, ethyl or benzyl
R
2
=an alkyl residue with 8 to 20 C atoms, where
t=1, 2 or 3.
X
−
=Cl
−
, Br
−
, I
−
or (alkyl sulfate)
−
Monomers a) are preferably chosen mainly from the (meth)acrylic acid esters. Especially preferred are polymers in which monomers b) are (meth)acrylic acid esters of general formula (II)
[CH
2
═CR
3
—CO—(O—CH
2
—CHR
4
)
n
]
m
-N
⊕
(CH
3
)
4−(m+t)
-(R
2
)
t
.X
−
  (II)
where
m=1, 2 or 3, n=2 to 40,
R
2
=an alkyl residue with 8 to 20 C atoms, where t=1, 2 or 3.
R
3
=H or CH
3
,
R
4
=H or CH
3
X
−
=Cl
−
, Br
−
, I
−
or (alkyl sulfate)
−
Although the mechanism of action is not understood, the inventors assume that monomers b), in which a combination of the quaternary ammonium group which contains at least one long-chain alkyl residue and which is bound to a hydrophilic spacer represents the active principle having antimicrobial activity in the polymers according to the invention. This was in no way foreseeable. The use of monomers, especially (meth)acrylic acid esters, which contain vinyl groups and which can undergo radical polymerization to form the antimicrobial polymers opens diverse possibilities of controlling the further polymer properties such as glass transition temperature, minimum film-forming temperature, molecular weight, etc., and so antimicrobial polymers are accessible for a multitude of applications.
WORKING OF THE INVENTION
The polymers according to the invention with antimicrobial properties can be obtained in a way known in itself by radical polymerization of the monomers in the presence of polymerization initiators and if necessary molecular weight regulators.
For this purpose there are used a) nonfunctional vinyl-type polymerizable monomers and b) functional vinyl-type polymerizable monomers of general formula (I). The term functional monomers relates to monomers b) in the sense that the antimicrobial property of the polymers is attributed to their presence.
For the present purpose, an antimicrobial property is understood as a germ-reducing or germ-killing action which occurs when the polymer and germs come into contact with one another in the presence of water.
Monomers a):
Examples of suitable nonfunctional vinyl-type polymerizable monomers according to a) are acrylate or methacrylate compounds, allyl compounds, styrenes, maleic acid, maleic anhydride or other vinyl compounds, such as vinyl esters, etc.
Monomers a) preferably comprise mainly (meth)acrylate compounds, or in other words such compounds account for at least 90% relative to the total quantity of monomers a). Of course, relatively small proportions such as up to 10% of other monomers a) can also be included. Preferred are alkyl (meth)acrylates with 1 to 20 C atoms in the alkyl residue, hydroxy (meth)acrylates or even (meth)acrylate compounds with acid or amide functions. Examples are methyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, hydroxyethyl (meth)acrylate, acrylic acid, methacrylic acid, acrylamide, methacrylamide. Relatively small proportions of cross-linking compounds such as glycol dimethacrylate or allyl methacrylate can also be included. Preferred monomers are alkyl (meth)acrylates. Especially preferred monomers a) are methyl methacrylate and butyl acrylate.
Monomers b):
Functional vinyl-type polymerizable monomers according to b) have the general structure of formula (I)
[V-A
y
-HSp]
m
-N
⊕
(R
1
)
4−(m+t)
-(R
2
)
t
.X
−
  (I)
where
V=vinyl, (meth)acroyl, allyl or styryl; (meth)acryloyl is preferred
A=a linking unit which is present if necessary, which can be alkyl, aryl, arylalkyl or hydroxyalkyl, and which can also be interrupted by heteroatoms, for

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