Synthesis and characterization of hyperbranched polyurethanes via monomeric A₂ plus monomeric B₃ approach

Abstract

The monomeric A2 plus monomeric B3 approach was employed to prepare hyperbranched polyurethanes (HBPUs) based on 4,4′‐methylenediphenyl diisocyanate and trimethylolpropane with the molecular weights ranging from 20,000 to 59,800 g mol−1. Through controlling the concentration and stoichiometric ratio of monomers, gel was successfully prevented in the monomeric A2 plus monomeric B3 system. The structures of HBPUs were characterized by 13C NMR. Molecular weights of HBPUs were characterized by gel permeation chromatography. A gradual increase in HBPU molecular weight as well as degree of branching was observed when the stoichiometric ratio of A2 to B3 increased. It was exhibited that the solution concentration of the reaction had great effect on the gel point and cyclization of the monomeric A2 plus monomeric B3 system. This novel isocyanate terminated HBPUs are expected to be capable of modifying the curing performance of benzoxazine resin. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and characterization of isocyanate-functionalized hyperbranched polyurethane and its cocuring with benzoxazine

“…In this work, HPU NCO can be successfully obtained via using monomeric A 2 plus monomeric B 3 approach with MDI as A 2 and TMP as B 3 monomers. For example, gel can be avoided when the stoichiometric ratio of A 2 to B 3 even reach 1.5:1 through carefully controlling the reaction conditions, such as temperature, the stoichiometric ratio of A 2 :B 3 , and the solution concentration of monomers . The content of isocyanate group is 6.21% calculated by weight of HPU NCO .…”

“…b, which are assigned to the quaternary carbon for the dendritic, linear, and terminal groups from TMP. As compared with model compounds that represent dendritic unit, linear unit, and terminal unit, respectively , DB value of HPU NCO is 35.2% determined with formula (1). It should be noted that the value below the predicted 50% for HBPs synthesized with the same molar ration of A 2 to B 3 .…”

Synthesis and characterization of aliphatic-aromatic hyperbranched polyesters with high organosolubility

“…HBPET with the structure ranging from aromatic to aliphatic as well as partial aromaticaliphatic structures have been investigated in many publications [1,[8][9][10][11].…”

“…SMM refers to the preparation of HBPs based on AB n monomers or potential AB n monomers, such as dimethylol propionic acid (DMPA). While DMM refers to the preparation of HBPs through copolymerization reaction of two types of monomers [10].…”