Solid-state NMR characterization of unsaturated polyester thermoset blends containing PEO–PPO–PEO block copolymers

Dynamics-based selective 2D 1H/1H chemical shift correlation spectroscopy under ultrafast MAS conditions

“…This observation is quite opposite to the dipolar filter under static conditions, where the dipolar filter strength increases (resulting in faster signal decay) with increasing the inter-pulse delay. 48,49 However, for the rotorsynchronized dipolar filter, the dipolar filter strength decreases with increasing the inter-pulse delay (i.e., increasing n with n ≤ 12 and n 3k) due to the MAS interference. According to the decay rate of signals from the rigid NH 3 + and the most mobile CH 3 given in Fig.…”

“…In principle, the proton transverse relaxation time in solid systems is mainly determined by the 1 H-1 H dipolar couplings, which means that the proton signals experiencing strong dipolar couplings will be filtered out first. Because of this reason, the 12-pulse dipolar filter sequence has been utilized in the investigation of the mobility of absorbed ligands on the surface of nanoparticles, 46,47 to measure the domain size in a multiphase system, 44,48,49 and the chain interpenetration and compatibility in polymer glasses. 50,51 In order to overcome the destructive interferences between MAS averaging and RF-pulses of the dipolar filter, here we utilized a rotor-synchronized dipolar filter with C N v n symmetry to filter out signals from rigid components of the system.…”

Rigid phase domain sizes determination for poly(urethane–urea)s by solid-state NMR spectroscopy. Correlation with mechanical properties

“…The dependence showed a linear trend with mixing time at small values, the former increasing, as expected in the case of a two-phase system with a small interfacial thickness with respect to the size of the different domains. The dependence does not start from the origin due to the interphase zone [17]. The presence of this interphase zone is connected with a competition between urethane and ether oxygen atoms in forming hydrogen bonds.…”

“…Using reference material (PMMA-PS diblock copolymer with D ref ¼ 0:8 nm 2 /ms, Dm ref 1=2 ¼ 38 kHz, and hr 2 i ¼ 0:0625 nm 2 ) one can obtain diffusion coefficient of the rigid phase D B [8]. The spin-diffusion coefficients for mobile phase were calculated using T 2 measurements of mobile fraction by method proposed by Li et al [17]. The values of D A and D B calculated under static conditions were assumed to be equal to 0.3 nm 2 /ms and 0.73 nm 2 /ms accordingly and were used for domain size determination.…”

Microphase Separation in Unsaturated Polyester/ PEO‐PPO‐PEO Block Copolymer Mixtures Containing Carbon Nanotubes

“…This phase behavior and microdomain structure agreed with that obtained by other authors for similar systems. 4 Irregular nanoscale micelle-shaped morphologies were obtained due to the immiscibility of a PPO block with the matrix and the possible expelling of a fraction of the PEO block from the UP network during curing. The morphologies were very similar for all compositions studied, increasing the number and size of irregular spherical-like micelles with the copolymer content.…”