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Polycaprolactone is one of the biodegradable polymers with good drug permeability. In the present paper, polycaprolactone and three kinds of copolycaprolactone–polycaprolactone–poly(ethylene oxide)– polycaprolactone triblock copolymer (PCE), polycaprolactone/polycaprolactone-poly(ethylene oxide)/polylactide tricomponents random block copolymer (PCEL) and polycaprolactone/poly(ethylene terephthalate) random block copolymer (PETCL)– were synthesized. The biodegradation behavior of these polymers were shown by degradation tests in vitro, ex vivo and in vivo. The oxygen permeabilities of these polymers were in the range of 10−10 ∼ 10−9 cm3 (STP) cm/cm2 sec cm Hg. Copolymers PCE and PCEL displayed O2 and N2 permeability coefficients (PO2/PN2) ratios of about 9. The effects of composition and crystallinity of the copolymers on biodegradability and the oxygen permeability of the polymer were discussed. Copyright © 1999 John Wiley & Sons, Ltd.

The surface properties of polycaprolactone (PCL)–poly(ethylene glycol) (PEG) block copolymer (PCE) and blend (B-PCE) of PCL and PEG obviously affect the drug release behavior of the polymer. In this paper, both surface properties of PCE and B-PCE are studied and compared by measuring their water sorption and using the contact angle and X-ray photoelectron spectroscopy technique. The effect of the polyether segment content in PCE and B-PCE on hydrophilicity is discussed. The results show that a hydrophilic polyether segment moves towards the surface and enriches on the surface for either PCE or B-PCE. The enrichment content of the polyether segment of PCE and the hydrophilicity of its surface are higher than that of B-PCE. A reason for the different drug release rates for PCE and B-PCE is suggested.

Copolymers of N-substituted methacrylamide (1a, b), new biomaterials, were synthesized to be used as encapsulating membranes of carbon kidney. In order to obtain a copolymer with a suitable hydrophilic property, the aminolysis of styrene-methyl methacrylate (St-MMA) copolymer with N-(2-hydroxyethyl)ethylenediamine was carried out under various conditions. The occurrence of aminolysis was confirmed by elemental analysis, IR and 1H NMR spectra. It was shown that a copolymer of N-substituted methacrylamide with a predictable degree of hydrophilicity can be obtained by controlling the composition ratio of the St-MMA copolymer and the degree of aminolysis of the copolymer. Hemoperfusion experiments with a living animal (dog), using a minicolumn with several types of microspheric activated carbon encapsulated with various copolymers, showed that copolymers with suitable hydrophilicity and hydrophobicity or with proper structure have a good blood compatibility. Studies with creatinine, uric acid and vitamin B12 showed that microspheric activated carbon, encapsulated with N-substituted methacrylamide copolymers of proper hydrophilicity and structure, has a good penetration property, and that detaching of activated carbon particles is effectively prevented.

A new type of polyether-polyester block copolymer (MPEE) consisting of two components of polyethers (PTMGT and PEGT) as soft segment and one polyester (PET) as hard segment has been synthesized. It has also been investigated in comparison with blended polyether-polyester block copolymer (BPEE) consisting of the same composition ratio of hard and soft segments and both of the two polyethers (PTMG and PEG). It was found that 1) Improvement of blood compatibility of polyether-polyester block copolymer can be achieved by introducing the hydrophilic component PEG into it; 2) generally the blood compatibility of MPEE is better than that of BPEE; 3) at a specific molar ratio of PTMGT-PET to PEGT-PET (60/40), the blended copolymer (BPEE 60/40) shows the best blood compatibility, as well as the best mechanical properties. This might be related to smaller-size microphaseseparated structures. The relationship between blood compatibility and structure of the copolymer is discussed. Polyether-polyester block ...

The blood compatibility of polymer is strongly influenced by surface properties of multicomponent polyether polyester block copolymer, such as contact angle, water sorption and microphase separated structure of the copolymer. The X-ray photoelectron spectroscopy test shows that the concentration ratio of oxygen to carbon on the sample-air interface is greater than that in the bulk, suggesting the diffusion of ether-bond towards the air surface. The biggest contact angle, the greatest increasing degree of O/C, and the most tiny microphase separated structure were found in the polyether polyester block copolymer composed of 60%—(PTMGT) and 40%—(PEGT) as soft segment, and this was the best material for blood compatibility.