Tocopherol Co-Catalyst Ring Opening Polymerisation Polysiloxanes
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Solution Overview
Problem
The existing methods for ring opening polymerization of cyclic siloxanes require large amounts of catalysts, leading to cross-linking of polymers during storage, and lack a suitable co-catalyst to control the release rate of drugs in medical applications, especially for hydrophilic drugs where polydimethylsiloxane is hydrophobic.
Innovation Solution
The use of tocopherol as a co-catalyst in the ring opening polymerization of cyclic siloxanes, reducing the amount of catalyst needed and minimizing cross-linking, while allowing for the production of hydrophilic polysiloxanes that can be easily cross-linked to form a drug delivery system with controlled release rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large amount of phosphazene base catalyst is used in ring opening polymerisation of cyclic siloxanes, then the polymerisation reaction proceeds efficiently, but cross-linking of the polymers occurs during storage
Solution Approach 1:
Tocopherol acts as an intermediary substance between the phosphazene base catalyst and the cyclic siloxane monomer. It forms a complex with the catalyst that moderates the catalyst's activity, allowing efficient polymerisation while preventing excessive reactivity that would cause cross-linking during storage.
Solution Approach 2:
The invention changes the chemical state and reactivity parameters of the catalyst system by introducing tocopherol. This modification allows the catalyst to maintain high polymerisation efficiency while reducing the harmful side effects of cross-linking during storage.
2Stability of the object's composition
If polydimethylsiloxane is used as a membrane material, then the membrane is stable and temperature resistant, but it cannot be used for hydrophilic drugs due to hydrophobicity
Solution Approach 1:
The invention creates a composite membrane material by combining polydimethylsiloxane with hydrophilic polymers or hydrophilic modifying agents. This composite structure maintains the thermal stability and mechanical strength of PDMS while introducing hydrophilic characteristics that enable compatibility with hydrophilic drugs.
Solution Approach 2:
The invention modifies specific local regions of the PDMS membrane by incorporating hydrophilic groups or phases at controlled locations. This allows the membrane to maintain its overall stability and temperature resistance while creating localized hydrophilic pathways for drug release.
3Shape
If the dimensions of the delivery device cannot be modified, then the device structure remains fixed, but the release rate of the drug cannot be significantly changed
Solution Approach 1:
The invention changes the chemical composition parameters of the membrane material to control drug release rate. By adjusting the ratio of hydrophilic to hydrophobic components, the diffusion properties of the membrane are modified, enabling significant changes in release rate without altering device dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in polysiloxane polymers that are free from undesired cross-linking, enabling precise control of drug release rates and maintaining mechanical properties, with the ability to form platinum-free elastomers suitable for medical applications.
Implementation Method 1
The present invention thus relates to the use of tocopherol as a co-catalyst in the ring opening polymerisation of cyclic siloxanes
Implementation Method 2
wherein a hydrido-containing cyclic siloxane is reacted with a hydrophilic molecule comprising a carbon-carbon double bond
Implementation Method 3
and polymerising said monomer in the presence of a second catalyst and tocopherol as a co-catalyst
Implementation Method 4
comprising cross-linking a polysiloxane in the presence of a cross-linking catalyst
Data Source
AI summary
The present invention relates to the use of tocopherol as a co-catalyst in the ring opening polymerisation of cyclic siloxanes. The present invention further relates to a method for manufacturing hydrophilic polysiloxanes, wherein a hydrido- containing cyclic siloxane is reacted with a hydrophilic molecule comprising a carbon-carbon double bond, having the general formula (I) H2C=CH-(CHR)n-O- (CHR1CR2R3)mR4 or (II) H2C=CH-(CHR)n-R5, wherein n is an integer from 0 to 4, m is an integer from 0 to 5, R, R1, R2, R3 and R4 are each independently hydrogen or a C1 to C6 alkyl, R5 is a saturated cyclic hydrocarbon containing carbonyl group, in the presence of a first catalyst to obtain a monomer, and polymerising said monomer in the presence of a second catalyst and tocopherol as a co-catalyst.