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New Paradigm in the Design of Degradable Polymeric Materials - Macroscopic Performance Translated to all Levels of Order

Final Report Summary - PARADIGM (New Paradigm in the Design of Degradable Polymeric Materials - Macroscopic Performance Translated to all Levels of Order)

The overall aim of this project was to create a new generation of polymeric materials, with sustainable interactions with the environment and with controllable degradation patterns. These new systems are composed of micro- or nano-particles held together by secondary bonds with changeable strength. These materials are purposely structurally engineered to be macroscopically homogeneous while microscopically heterogeneous.

During the lifetime of the project, several research and technological achievements have been accomplished. Much effort has been devoted to developing a system that can create tailor-made polymer particles in high yield, subsequent viable surface modification routes, as well as the direct synthesis of self-organizing polymers and polymers containing functional groups.
The main objective has been to create dynamic systems for tissue engineering applications, as well as sustainable materials for commodity applications. This includes self-assembly, microspheres interconnected by secondary forces such as hydrogen bonding and ionic forces, stimuli responding polymers, tailored hydrophilicity to minimize biofouling etc. The key constituent in these systems are polymer particles of various forms and functions. The initial focus has therefore been on creating particles with desired properties i.e. size, shape, and size distribution. Firstly, we developed and/or improved four methods for producing PLA particles; oil-in-water emulsion, nanoprecipitation, electro-spraying and cryogenic milling, methods that are all complimentary with respect to the size and shape of the resulting particles. Furthermore, we developed a system that can create sub-micron sized stereocomplexed particles in high yield and with high throughput by means of a spray dryer. PLA-based core-shell particles have been achieved by having PLA stereocomplex and a rubbery type copolymer in the formulation.

We have established several important parameters that control the degradation rate and profile of our materials, including the ability to induce degradability to non-degradable polymers, to control the degradability of the materials by controlling their miscibility or by inducing stereocomplex formation. Further, biopolymer-based hydrogels have been created and made conducting as a step towards a floating extracellular matrix. Much effort has been dedicated to broaden the platform of polymers and properties available. Alternative routes to design degradable aliphatic polyesters and combinations of inert and degradable polymers have therefore been explored. We have also established a bridge between two different initiating systems by using a duo-functional monomer.

The kinetic and thermodynamic dependence of the polymerization behavior and the final properties of a polymer have been investigated by using a monomer-specific “on/off-switch”. This approach has made it possible to synthesize multi-block copolymers at a high level of control. Recently, we have investigated the thermodynamic equilibrium behavior in relation to the monomer structure. This information offers an additional level of complexity to the molecular toolbox and enables a powerful route to both monomer formation and intentional macromolecular design.

Finally, in this project we have demonstrated new and unconventional routes to design new degradable polymeric materials, where the macroscopic performance is translated to all levels of order. A total of 35 articles have been published in peer reviewed journals as well as 31 contributions to international conferences, which all have important contents that contribute to the progress of the project.