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Cho, Tai-Yon

doi:10.1142/s025676790700187x

Cited by 10 publications

(6 citation statements)

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“…As shown recently for poly(L-lactide), this can be achieved by an ordering of the fold surface. 19 Application of the model in the data evaluation implies to identify the crystallization line and the melting lines in Figure 1 with transition lines in a d c -1 /T nanophase diagram: (i) the melting line with the thickness dependent melting point of stabilized crystallites; (ii) the crystallization line with the thickness-dependent transition between a layer with mesomorphic structure and a crystal layer in the initial, i.e., not yet stabilized, form.…”

Section: Data Evaluation Based On Multistage Modelmentioning

confidence: 99%

Depression of the Zero Growth Temperature by Counits Observed for s-Polypropylene in Light Attenuation Experiments

2009

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The growth rate of polymer crystals decreases exponentially with rising temperature, thus indicating a growing activation barrier. The barrier is proportional to the inverse of the supercooling below the "zero growth temperature" T zg , which is always located below the equilibrium melting point. In order to see the effect of counits on T zg , we studied with time-dependent light attenuation measurements the growth kinetics of s-polypropylene and a derived statistical copolymer with 15% of octene counits. Using a homebuilt device, we achieved a sensitivity superior to DSC or X-ray experiments. An accurate extrapolation procedure yielded for both samples the zero growth temperature. The counits lead to a downward shift of T zg by 40 K, which is larger than the downward shift of the melting point (30 K). We interpret the results in the framework of our multistage model which assumes participation of a transient mesophase in the growth process of polymer crystals. T zg is identified with the equilibrium melting point of the mesophase. Knowledge of T zg allows to establish for both samples a size-temperature nanophase diagram. Data evaluation yields the heat of melting and the surface free energy of mesomorphic layers as well as the activation barrier per monomer.

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Section: Data Evaluation Based On Multistage Modelmentioning

confidence: 99%

Depression of the Zero Growth Temperature by Counits Observed for s-Polypropylene in Light Attenuation Experiments

2009

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“…Vinylcyclopropanes (VCPs) with two radical‐stabilizing groups (cyano, [ 1–4 ] ester, [ 2–7 ] and amide [ 8,9 ] ) undergo radical ring‐opening polymerization (RROP) to yield polymers with CC bonds in main chains. [ 1–14 ] As shown in Scheme 1a, the vinyl group of VCP derivative reacts with radical species. After that, the resulting radical will be transformed into an acyclic radical species via the preferential cleavage of C1‐C2 bond on VCP moiety.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of reactive polyureas bearing vinylcyclopropane moiety in main chain and their radical cross‐linking with multifunctional thiols

Okamoto

Sudo

Endō

2020

Journal of Polymer Science

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A series of polyureas 5a-c bearing vinylcyclopropane (VCP) moiety in their main chains was synthesized by the polyaddition of diamine 2 bearing VCP moiety with diisocyanates. Upon treatment of polyurea 5b with thiols in the presence of azobisisobutyronitrile (AIBN), the VCP moieties in the polymer main chain efficiently reacted with the thiols via a sequence of the radical addition of thiol to the vinyl group and the ring opening of the cyclopropane ring, yielding the corresponding networked polymers 9-11. The thermogravimetric analysis of the networked polymers 9-11 revealed that their residual weight at 350 C was higher than that of the precursor polyurea 5b. K E Y W O R D Scross-linking, radical ring-opening reaction, reactive polyurea, vinylcyclopropane

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“…These MSUs with built-in sequence information can be linear or cyclic, and the polymerization of them can be either chain or step growth polymerization. [6][7][8][9][10][11] Though the resulting polymers from this approach only have periodic sequences, the diversity of polymer structures can be rather broad, since the MSUs can be constructed by effi cient organic synthesis rather fl exibly. Moreover, different polymerization methods and coupling reactions can be used to get the desired copolymers.…”

Section: Introductionmentioning

confidence: 99%

Combination of ATRA and ATRC for the Synthesis of Periodic Vinyl Copolymers

Wang

Song

Deng

et al. 2013

Macromol. Rapid Commun.

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A new approach to periodic vinyl copolymers via combination of atom transfer radical addition (ATRA) and atom transfer radical coupling (ATRC) is reported. The two examples are methyl methacrylate (MMA) and styrene (St) periodic copolymer (P(SMMS)) and acrylonitrile (AN) and St periodic copolymer (P(SAAS)). First, two monomer sequence units (MSU) with built-in sequence, SMMS and SAAS, are synthesized through the controlled ATRA of two ATRP initiators with St. Then, the ATRC of SMMS and SAAS are conducted at high radical conditions to generate two types of high-molecular-weight copolymers, P(SMMS) and P(SAAS). Though side reactions can not be totally avoided, characterizations of the polymer structure with a variety of means confirm that the main chain structures of P(SMMS) and (PSAAS) are predominantly with the periodic sequences from the MSUs. Attempts to suppress the side reactions are successful via the MNP-mediated ATRC of SMMS and SAAS.

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Cited by 10 publications

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Depression of the Zero Growth Temperature by Counits Observed for s-Polypropylene in Light Attenuation Experiments

Depression of the Zero Growth Temperature by Counits Observed for s-Polypropylene in Light Attenuation Experiments

Synthesis of reactive polyureas bearing vinylcyclopropane moiety in main chain and their radical cross‐linking with multifunctional thiols

Combination of ATRA and ATRC for the Synthesis of Periodic Vinyl Copolymers

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