Blood interface biomaterials - Biomaterials and Devices for the Circulatory System - page 32

PEO

Macromonomer
(vinyl-PEO)

PEO-F
(activated PEO)

Homopolymer
or IPN
formation

Physical adsorption/
chemical
immobilisation

Grafting
copolymerisation

Block
copolymerisation

Physical
adsorption

Immobilisation

PEO-modified materials PEO-containing material

Coating material Blending additives

2.1 Molecular design of PEO-modifi ed surface (IPN = interpenetrating
network).

exhibited excellent blood compatibility. PEO can also be grafted chemically
onto numerous polymeric surfaces, such as polyethylene (PE), PU (Han
et al. , 1993), haemodialysis cellulose membranes (Akizawa et al. , 1989) and
polytetrafl uoroethylene (PTFE) (Allmer et al. , 1990). PEO-modifi ed hae-
modialysis membrane surfaces have been found to reduce complement
activation (Akizawa et al. , 1989).
PEO-containing polymers can be built by block copolymerisation. Lee et
al. (1989, 1990) synthesised copolymers of alkyl methacrylates with methoxy
PEO methacrylates. The material produced can be used for coating. The
PEO surface prepared by adsorption of this synthesised PEO-grafted copo-
lymer showed effi cient protein-resistant character. Bergström et al. (1992)
utilised PEO to coat polystyrene a surface to achieve a reduced fi brinogen
adsorption. For a strong retention of PEO at the modifi ed surface, Lens
et al. (1997) developed alkyl-PEO surfactants, which contained a terminal
hydroxyl, sulphate or carboxylate group. By surface coating with these
surfactants, followed by argon plasma treatment, a PEO strongly bound
surface could be achieved.
PEO has been widely applied as a soft segment for PU biomaterials and
PEO-PU segmented hydrogels have demonstrated improved blood com-
patibility in terms of protein adsorption and complement activation (Yu
et al. , 1991).
PEO can be immobilised on surfaces by the Williamson reaction and
this has been employed for PEO modifi cation of PVC (Lakshmi &
Jayakrishnan, 1998).

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