title: Structure-property relationship in new photo-cured dimethacrylate-based dental resins.
abstract: OBJECTIVE
  In this study five novel dimethacrylates of different chain lengths having rigid aromatic rings were synthesized and proposed as possible dental monomers for dental resin mixtures.
  
  
  METHODS
  Four monomers were prepared by the reaction of glycidyl methacrylate with dicarboxylic acid esters obtained from phthalic anhydride and 1,3-propylene, 1,4-butylene, 1,5-penthylene and 1,6-hexylene glycols. The addition reaction of glycidyl methacrylate and the acidic compound was carried out in the presence of tetraethylammonium bromide. The fifth monomer was obtained from 1,5-penthylene glycol-based dimethacrylate by blocking its hydroxyl groups with acetyl groups. The monomers were photo-copolymerized with triethyleneglycol dimethacrylate (TEGDMA) in the presence of a photoinitiator which was 2,2-dimethoxy-2-phenyloacetophenone. Unfilled polymers were evaluated for photopolymerization conversion and volumetric curing shrinkage. Water sorption, water solubility, flexural strength and hardness were measured. The prepared polymers were also subjected to dynamic mechanical studies (DMA).
  
  
  RESULTS
  Results show that, increasing the distance between double bonds decreases flexural modulus and hardness. As expected, the curing shrinkage increased with increasing degree of conversion. The acetylation of hydroxyl groups resulted in improved water uptake properties of the compositions. It was demonstrated that, depending upon the content of acetyl groups in the network, the glass transition temperature may be significantly lowered. In polymers with large amounts of pendant groups, β relaxation overlaps with α relaxation (glass transition temperature), and it is the former that discloses the maximum on the tanδ curve.
  
  
  CONCLUSIONS
  The systematic change in the length of the new dimethacrylates provided insight into the effects on the resultant material properties. It was shown in the article that the properties of the new monomers compare favorably with properties of the commercially available resins.
authors.affiliation: Faculty of Chemistry, Department of Polymer Chemistry, MCS University, Lublin, Poland. m.podgorski@op.pl
authors.forename: Maciej
authors.initials: M
authors.lastname: Podgórski
mesh_terms: D000042:Absorption; D000180:Acrylic Resins / Q000737:chemistry*; D002072:Butylene Glycols; D003799:Dental Stress Analysis; D003998:Dicarboxylic Acids; D055119:Elastic Modulus; D004852:Epoxy Compounds; D006018:Glycols; D006244:Hardness; D017665:Hydroxyl Radical; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008689:Methacrylates / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D010795:Phthalic Acids; D018583:Pliability; D011092:Polyethylene Glycols; D058105:Polymerization; D019946:Propylene Glycol; D012995:Solubility; D013329:Structure-Activity Relationship; D044366:Transition Temperature; D014783:Viscosity; D014867:Water
chemical_list: D000180:Acrylic Resins; D002072:Butylene Glycols; D003998:Dicarboxylic Acids; D004852:Epoxy Compounds; D006018:Glycols; D008689:Methacrylates; D010795:Phthalic Acids; D014867:Water; D017665:Hydroxyl Radical; D011092:Polyethylene Glycols; D019946:Propylene Glycol; C011480:hexylene glycol; C007870:glycidyl methacrylate