Ring-opening polymerization of 1-methyltrimethylene carbonate (MTMC) initiated by highly active single-component rare earth tris(2,6-di-tert-butyl-4-methylphenolate)s [Ln(OAr) 3 , Ln ¼ La, Dy, Y] or yttrium isopropoxide [Y(OiPr) 3 ] is reported for the first time. PolyMTMC (M w ¼ 8.4 Â 10 4 , molecular weight distributions ¼ 1.5) initiated by La(OAr) 3 at [MTMC]/[initiator] ¼ 1000was obtained with the yield over 99% in toluene within 1 h at 30 C. Random and block copolymers of MTMC with e-caprolactone (CL), 2,2-dimethyltrimethylene carbonate (DTC) or polyethylene glycol (PEG) including poly(MTMC-r-CL), poly(MTMC-b-CL), poly(MTMC-r-DTC), poly(MTMC-b-DTC), and poly(MTMC-b-PEGb-MTMC) were synthesized. The differential scanning calorimetry results show that thermal behaviors of the polymers sensitively depend on their compositions and chain structures. Further-more, the measurements of 1 H-1 H COSY and density functional theory calculation are applied to investigate the mechanism. The polymerization of MTMC takes place according to a coordination-insertion mechanism, and the ring is opened via acyloxygen bond cleavage resulting in a LnAO active center. There exist two ring-opening modes of MTMC in which mode b, breaking the CH 2 OACO bond, is the major pathway. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3807-3815, 2010 EXPERIMENTAL Materials CL (Acros product, 99%) was distilled under reduced pressure after being stirred over CaH 2 for 12 h. DTC, Ln(OAr) 3 ,
Patternless binary coding strategies have been a challenge for ultra-fast 3D imaging with structured light. This Letter proposes a big codewords space division multiplexing binary coding method. From the third to the multiple order, a special spatial binary coding instead of the Gray code is created for the first time, to the best of our knowledge, to achieve an ultra-wide unambiguous range with only one auxiliary pattern. Advantageously, a connection domain segmentation technique with anomaly detection is proposed to achieve decoding of the fringe order, which cleverly avoids the misalignment problem. Additionally, a center of gravity method is applied to compensate for the codewords of the residual connected domain. The robustness and effectiveness of the proposed method for complex, isolated, and non-uniform reflectivity objects, as well as the ultra-fast 3D imaging of dynamic measurements, are experimentally verified.
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