Mass uptake study of the diffusion of water and SBF into poly(2-hydroxyethyl methacrylate-co-tetrahydrofurfuryI methacrylate) containing aspirin or vitamin B-12

The ingress of water and Kokubo simulated body fluid (SBF) into poly (2-hydroxyethyl methacrylate) (PHEMA), and its co-polymers with tetrahydrofurduryl methacrylate (THFMA), loaded with either one of two model drugs, vitamin 1312 or aspirin, was studied by mass uptake over the temperature range 298-318 K. The polymers were studied as cylinders and were loaded with either 5 wt% or 10 wt% of the drugs. From DSC studies it was observed that vitamin B-12 behaved as a physical cross-linker restricting chain segmental mobility, and so had a small anti-plasticisation effect on PHEMA and the co-polymers rich in HEMA, but almost no effect on the T-g of co-polymers rich in THFMA. On the other hand, aspirin exhibited a plasticising effect on PHEMA and the copolymers. All of the polymers were found to absorb water and SBF according to a Fickian diffusion mechanism. The polymers were all found to swell to a greater extent in SBF than in water, which was attributed to the presence of Tris buffer in the SBF. The sorptions of the two penetrants were found to follow Fickian kinetics in all cases and the diffusion coefficients at 310 K for SBF were found to be smaller than those for water, except for the polymers containing aspirin where the diffusion coefficients were higher than for the other systems. For example, for sorption into PHEMA the diffusion coefficient for water was 1.41 X 10(-11) m(2)/s and for SBF was 0.79 x 10-11 m(2)/s, but in the presence of 5 wt% aspirin the corresponding values were 1.27 x 10(-1)1 m(2)/s and 1.25 x 10(-11) m(2)/s, respectively. The corresponding values for PHEMA loaded with 5 wt% B-12 were 1.25 x 10(-11) m(2)/s and 0.74 x 10(-11) m(2)/s, respectively.

Courtyard, Hill House, Chapel Hill, Brisbane

Central courtyard space. Door to master bedroom and ensuite on right.

Upper west elevation, Hill House, Chapel Hill, Brisbane

Ensuite corner window in foreground on right, with planter to garden on left.

Trusses, Hill House, Chapel Hill, Brisbane

Trusses to living room roof.

Garden, Hill House, Chapel Hill, Brisbane

As seen from master bedroom, looking across to living room.

Garage, Hill House, Chapel Hill, Brisbane

Garage with store above (south elevation).

Courtyard, Hill House, Chapel Hill, Brisbane

Central courtyard space with strip windows to kitchen/dining on left.

Kitchen, Hill House, Chapel Hill, Brisbane

Dining room and courtyard space beyond.

Courtyard, Hill House, Chapel Hill, Brisbane

Courtyard to west elevation at completion of construction. Planter in foreground to right.

Courtyard, Hill House, Chapel Hill, Brisbane

Paved courtyard area to Western elevation.

West elevation, Hill House, Chapel Hill, Brisbane

As seen from the street, looking north-east.

Door openings, Hill House, Chapel Hill, Brisbane

Openings under construction.

Fireplace, Hill House, Chapel Hill, Brisbane

Fireplace to living room.

Entry hallway, Hill House, Chapel Hill, Brisbane

As seen from top of stairs.

Entry, Hill House, Chapel Hill, Brisbane

Entry stairs and front door, with garden area beyond.