Material Development.

Monomer Development & Synthesis

Our team has extensive experience in the development of polymers and materials used in the biomaterials field, including those used for drug delivery. In particular, our group has extensive experience using acrylic polymers polymerized using free-Radical (UV and thermal) and Controlled Radical Polymerization techniques (i.e. RAFT and ATRP) and silicone chemistry. We have the knowledge to help others to develop new polymers for a variety of applications.

Polymer Design

Our team has a wealth of experience in the development of new polymers for a variety of applications in the biomaterials field. We can help design custom monomers and polymers with the desired properties or take it further and develop and execute the synthetic procedures to make the desired polymer (i.e. surfactants, block co-polymers, etc.). We will work with you and everything can be customized to exactly what is needed.

Material Modification

Our team has a wealth of experience in the development and surface and bulk modification of materials for a variety of applications in the biomaterials field. We can help design new polymeric materials or modify existing materials to impart desired properties. We can also take it further and develop and execute the synthetic procedures to make/modify the materials for you. We will work with you and everything can be customized to exactly what is needed.

In particular, we have experience with the following bulk and surface modifications:

• Incorporation of PEG and HA to bulk and surface of hydrogel and silicone hydrogel to improve water content and wettability
• Incorporation of PBA and chitosan to bulk and surface to improve mucoadhesion properties of materials
• Adding another polymer through copolymerization or physical entanglement to increase drug interaction with the materials so that leads a more sustained release.
• Drug Tethering

Polymer & Material Characterization

Whether working with an existing polymer/material or something new, we have a wealth of experience in characterizing polymers and materials. Our strength is not only conducting these tests skilfully, but also having expertise to analyze the test data and correlate the results to the material development strategies to provide valuable consultations.

Polymers:

• Find the average composition
• Find the molecular weight and dispersity
• Polymer behavior and stability at different temperatures
• For solutions of surfactant we can find the size of aggregates the critical micelle concentration
• GPC for examining molecular weight and degradation test of a polymer material
• DSC, TGA for thermal analysis to determine Tg (glass transition temperature), LCST (low critical solution temperature), melting point, and decomposition temperatures etc.
• NMR, FTIR for chemical structure and material composition confirmation

Materials:

• Surface and bulk properties such as wettability, composition, morphology, response to variations in temperature, modulus, elasticity, transparency, water uptake, oxygen permeability
• TEM and SEM for investigating morphology of bulk materials and nanoparticles
• XPS, Goniometer and ATR-FTIR for surface property tests
• Instron machine for Mechanical testings including modulus, tensile strength and tear strength measurements
• DLS for determining particle size and distribution

Contact Lens Characterization

Silicone Hydrogels
In line with current contact lens manufacturing technologies, UV free radical polymerization and crosslinking are majorly used in C2020 contact lens team to synthesize different model contact lens material per client’s requests including conventional hydrogel and silicone hydrogel contact lenses for both flat lenses in material modification stage and molding of lenses with curvature in actual application tests. Besides the commonly used monomer HEMA, the other monomers including EGDMA, PVP, PVA and TRIS silicone monomers are also employed in the lens preparation for different purposes and projects.

Polymerization conditions including ratios in recipe, initiator type, temperature and UV intensity etc. can be altered to produce the same type of polymer materials with different properties. With an emphasis on material science employed in developing new contact lenses and related modifications for different application, more extensive contact lens modification solutions can be further provided for need of improving different properties as listed below.

Mechanical properties and water content can be regulated by altering crosslinking density or incorporating another monomer with different hydrophilicity. Enhancing contact lens material tensile strength and tear strength can be achieved by increasing crosslinking density or copolymerizing with a monomer which results in more rigid or more hydrophobic polymer. In some cases, adding a soft polymer can reduce the modulus of particularly tough materials (often silicone-based materials). Instron machine equipped with 15N and 50N load cell is used to measure tensile strength, modulus and tear strength of the materials. We also have custom-made small cuter and small clamps to hold such tender and small size contact lens specimens.

Water content and surface wettability can be improved by copolymering with MAA, NVP or PVA monomers to increase the water content of hydrogels due the strong hydrophilic character arising from amine, carboxylic acid, hydroxyl groups, etc. Therefore, these comonomers also influence the wettability of the surface.

Silicone-based comonomers or silicone containing additives add oxygen permeability to contact lens materials that require improvement to this property.

Our team understands that a balance must be reached between these parameters when designing or modifying a contact lens for a particular application.

Our facility holds whole stream of contact lens characterization and evaluation tools listed in ISO18369-4 including extractable using Soxhlet extractor, oxygen permeation test using polarographic method (Dk testing), refractive index and water content tests. In addition, transparency ranging from 400-800nm can be measured using UV-VIS spectrophotometer. Water contact angle of contact lens surface wettability characterization can be conducted using a goniometer on site.

Protein and lipid deposition on the contact lens remains a concern related to discomfort of the lens, particularly for HEMA based contact lenses containing silicone. Our team has developed special techniques for precise lipid and protein adsorption quantification using radiolabeling method. Also protein distribution through out the lens can be also visualized through confocal microscopy.

Modulus, transparency, oxygen permeability, surface wettability, water content and water contact angle etc.

Troubleshooting/Support

We are happy to consult and provide support to help troubleshoot synthetic challenges, difficulties in characterizing materials or help with data analysis. The combined and varied experience of our team members contain a wealth of knowledge and are up to any challenge.