IADR Abstract Archives
Modifying or Creating Polymer Networks with Nanogels
Objectives: Prepolymeric nanoparticles (nanogels) can be prepared with extensive control over features such as internal network structure and reactive group density. Solvent of appropriate solubility parameter readily infiltrates and disperses nanogels, which when loaded above percolation threshold can efficiently form macroscopic networks through polymerization between overlapping nanogel particles. When a monomer is used as the dispersant, the interparticle polymerization is combined with nanogel copolymerization with the matrix to create unique network structures. This study uses nanogels dispersed in either inert or reactive matrices to probe the structure and properties that can be developed.
Methods: Discrete ~10nm nanogels with methacrylate reactive groups located throughout the particles were prepared from HEMA/BisEMA as one example among others. The nanogel was loaded at 50 wt% in glycerol dimethacrylate (GDMA) or HEMA as reactive matrices as well as in acetone as an inert matrix. The transparent formulations were photopolymerized to give bar-shaped specimens for dry and wet testing of flexural modulus. Homopolymer specimens of HEMA and GDMA were applied as controls.
Results: When dispersed and photocured in acetone, the dry/wet modulus of the HEMA/BisEMA nanogel network was 619±82/648±84MPa. For comparison, the dry/wet modulus of bulk poly(HEMA) control was only 8.0±0.3/0.30±0.01MPa while the HEMA/BisEMA nanogel dispersed in HEMA gave 1711±119/217±19MPa. When tested dry, the highly crosslinked bulk cured GDMA had a modulus of 1411±95MPa and the HEMA/BisEMA nanogel dispersed in GDMA produced an equivalent value of 1493±77MPa. However, as noted both these values were significantly below that achieved with the HEMA/BisEMA nanogel dispersed in acetone.
Conclusions: These modulus results demonstrate that high density, high strength 3D polymeric networks can be generated with nanogels dispersed in either crosslinking monomer, monovinyl monomer or even in an inert solvent. HEMA used as a matrix for nanogel networks produces much lower wet strength compared to the same nanogel network formed in an inert solvent.
Methods: Discrete ~10nm nanogels with methacrylate reactive groups located throughout the particles were prepared from HEMA/BisEMA as one example among others. The nanogel was loaded at 50 wt% in glycerol dimethacrylate (GDMA) or HEMA as reactive matrices as well as in acetone as an inert matrix. The transparent formulations were photopolymerized to give bar-shaped specimens for dry and wet testing of flexural modulus. Homopolymer specimens of HEMA and GDMA were applied as controls.
Results: When dispersed and photocured in acetone, the dry/wet modulus of the HEMA/BisEMA nanogel network was 619±82/648±84MPa. For comparison, the dry/wet modulus of bulk poly(HEMA) control was only 8.0±0.3/0.30±0.01MPa while the HEMA/BisEMA nanogel dispersed in HEMA gave 1711±119/217±19MPa. When tested dry, the highly crosslinked bulk cured GDMA had a modulus of 1411±95MPa and the HEMA/BisEMA nanogel dispersed in GDMA produced an equivalent value of 1493±77MPa. However, as noted both these values were significantly below that achieved with the HEMA/BisEMA nanogel dispersed in acetone.
Conclusions: These modulus results demonstrate that high density, high strength 3D polymeric networks can be generated with nanogels dispersed in either crosslinking monomer, monovinyl monomer or even in an inert solvent. HEMA used as a matrix for nanogel networks produces much lower wet strength compared to the same nanogel network formed in an inert solvent.