Surgical barrier possessing clinically important absorption characteristics
A technology of copolymers and components, applied in the field of surgical barriers with clinically important absorption properties, can solve problems such as difficult operations and variable results
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Embodiment 1
[0113] Example 1: Synthesis of A(BCB)A block of Poloxamer (Poloxamer) and polylactic acid
[0114] The final water content obtained by drying Pluronic 31R1 (molecular weight 3250) (BASF, Mt. Olive, NJ) (a copolymer of propylene oxide and ethylene oxide) in a spherical flask at 85°C for 12 hours under vacuum less than 300ppm. 10 g of Pluronic 31R1 were added to 2.1 g of (l)-lactide and 0.18 g of catalyst (stannous 2-ethylhexanoate) (0.43%). The reaction was carried out in a sealed flask at 145° C. for 2.5 hours under a dry nitrogen saturated atmosphere. The product is a copolymer of Pluronic and polylactic acid.
Embodiment 2
[0115] Embodiment 2: the A(B)A block of synthetic polyethylene glycol and polylactic acid
[0116] Polyethylene glycol (molecular weight 3000) was dried under vacuum at 85°C overnight. After this time, the PEG was cooled to room temperature, and the product was blanketed with dry nitrogen. 100 g of PEG was added to 18 g of (l)-lactide and 0.18 g of catalyst (stannous 2-ethylhexanoate). The mixture of PEG and lactide was placed in an oil bath at 140°C and mixed for 3 hours under flowing nitrogen. At the end of the 3 hour period, the mixture was removed from the oil bath, allowed to cool, dissolved in chloroform and precipitated in ether. Thereafter the precipitate was collected and dried in vacuo at 50°C overnight.
Embodiment 3
[0117] Embodiment 3: Synthesis of AD (BCB) DA block of poloxamer and polylactic acid
[0118] 2 moles of diisocyanate were placed under nitrogen in a reactor equipped with a stir bar. The contents were heated to 60°C and 1 mole of poloxamer diol (BCB) was slowly added. The poloxamer should be added at a rate slow enough that the temperature of the contents does not rise above 65°C. If the poloxamer is solid at 60°C, a solvent can be used. When all the poloxamer has been added to the reaction contents, the mixture will react until the isocyanate content corresponds to two available NCO groups per poloxamer molecule. Adding the poloxamer slowly ensures that each poloxamer molecule is capped with two diisocyanate molecules, since most of the reaction is performed in excess diisocyanate and chain extension of the poloxamer is unlikely . If it is important to prevent chain extension, a large excess of diisocyanate can be employed and evaporated at the end of the reaction.
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