Synthesis and photopolymerization of low shrinkage methacrylate monomers containing bulky substituent groups.
OBJECTIVE
This study was conducted to determine whether novel photopolymerizable formulations based on dimethacrylate monomers with bulky substituent groups could provide low polymerization shrinkage without sacrifice to degree of conversion, and mechanical properties of the polymers.


METHODS
Relatively high molecular weight dimethacrylate monomers were prepared from rigid bisphenol A core groups. Photopolymerization kinetics and shrinkage as well as flexural strength and glass transition temperatures were evaluated for various comonomer compositions.


RESULTS
Copolymerization of the bulky monomers with TEGDMA show higher conversion but similar shrinkage compared with Bis-GMA/TEGDMA controls. The resulting polymers have suitable mechanical strength properties for potential dental restorative materials applications. When copolymerized with PEGDMA, the bulky monomers show lower shrinkage, comparable conversion, and more homogeneous polymeric network structures compared with Bis-EMA/PEGDMA systems.


CONCLUSIONS
The novel dimethacrylate monomers with reduced reactive group densities can decrease the polymerization shrinkage as anticipated, but there is no significant evidence that the bulky substituent groups have any additional effect on reducing shrinkage based on the physical interactions as polymer side chains. The bulky groups improve the double bond conversion and help maintain the mechanical properties of the resulting polymer, which would otherwise decrease rapidly due to the reduced crosslinking density. Further, it was found that bulky monomers help produce more homogeneous copolymer networks.
Department of Chemical and Biological Engineering, University of Colorado, 80262, USA.
Junhao
J
Ge
Marianela
M
Trujillo
Jeffrey
J
Stansbury
D001559:Benzhydryl Compounds; D017438:Bisphenol A-Glycidyl Methacrylate / Q000138:chemical synthesis / Q000737:chemistry; D003764:Dental Materials / Q000138:chemical synthesis* / Q000737:chemistry / Q000528:radiation effects; D006801:Humans; D007700:Kinetics; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000138:chemical synthesis* / Q000737:chemistry / Q000528:radiation effects; D008970:Molecular Weight; D010636:Phenols / Q000737:chemistry; D018583:Pliability; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D011109:Polymethacrylic Acids / Q000138:chemical synthesis / Q000737:chemistry; D013499:Surface Properties; D044366:Transition Temperature; D000098826:Bisphenol A Compounds
D001559:Benzhydryl Compounds; D017438:Bisphenol A-Glycidyl Methacrylate; D003764:Dental Materials; D008689:Methacrylates; D010636:Phenols; D011092:Polyethylene Glycols; D011108:Polymers; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; C041979:2,2-bis-(4-(2-methacryloxyethoxy)phenyl)propane; C006780:bisphenol A; D000098826:Bisphenol A Compounds