Phase Transition from Tetragonal Form II to Hexagonal Form I of Butene-1/4-Methyl-1-pentene Random Copolymers: Molecular Factor versus Stretching Stimuli

2019 ◽  
Vol 52 (3) ◽  
pp. 1188-1199 ◽  
Author(s):  
Lirong Zheng ◽  
Long Liu ◽  
Chunguang Shao ◽  
Wei Wang ◽  
Bin Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Factor Versus ◽  
Random Copolymers ◽  
Hexagonal Form ◽  
Molecular Factor ◽  
Tetragonal Form

Interplay between Macroscopic Stretching and Microscopic Phase Transition Revealed in Butene-1/1,5-Hexadiene Random Copolymers

2020 ◽  
Vol 53 (6) ◽  
pp. 2145-2156 ◽  
Author(s):  
Wei Li ◽  
Long Liu ◽  
Lirong Zheng ◽  
Yahui Lou ◽  
Zhe Ma ◽  
...  
Keyword(s):  
Phase Transition ◽  
Random Copolymers

Phase Transition of a Structure II Cubic Clathrate Hydrate to a Tetragonal Form

2016 ◽  
Vol 55 (32) ◽  
pp. 9287-9291 ◽  
Author(s):  
Satoshi Takeya ◽  
Hiroshi Fujihisa ◽  
Hiroshi Yamawaki ◽  
Yoshito Gotoh ◽  
Ryo Ohmura ◽  
...  
Keyword(s):  
Phase Transition ◽  
Clathrate Hydrate ◽  
Tetragonal Form

Phase Transition of a Structure II Cubic Clathrate Hydrate to a Tetragonal Form

2016 ◽  
Vol 128 (32) ◽  
pp. 9433-9437 ◽  
Author(s):  
Satoshi Takeya ◽  
Hiroshi Fujihisa ◽  
Hiroshi Yamawaki ◽  
Yoshito Gotoh ◽  
Ryo Ohmura ◽  
...  
Keyword(s):  
Phase Transition ◽  
Clathrate Hydrate ◽  
Tetragonal Form

scholarly journals A study of vibrational dynamics of poly (a-n-butyl-b-l-aspartate) (panbla)

2009 ◽  
Vol 3 (1) ◽  
pp. 7-18
Author(s):  
Mahendra Singh ◽  
◽  
Anuj Kumar ◽  
Naresh Kumar ◽  
Poonam Tandon ◽  
...  
Keyword(s):  
Normal Modes ◽  
Internal Symmetry ◽  
Dynamical Behaviour ◽  
Least Square ◽  
X Ray Diffraction ◽  
Molecular Mechanics Calculations ◽  
Vibrational Dynamics ◽  
X Ray ◽  
Hexagonal Form ◽  
Tetragonal Form

Poly(-N-butyl--L-aspartate) (PANBLA) is nylon-3 derivative in which an alcoxycarbonyl group has been stereoregularly attached to -carbon of the repeating unit. Like poly(-isobutyl--L-aspartate) (PAIBLA) exists in two helical forms, namely hexagonal form (13/4 helix) and tetragonal form (4/1 helix), were characterized by X-ray diffraction. The hexagonal form appears to be poorly crystalline and it could not be obtained well oriented. On the other hand tetragonal form turns to be highly crystalline. Both molecular mechanics calculations and the linked-atom least square (LALS) methodology using X-ray diffraction data have revealed that an antiparallel packing of 13/4 helices with a right handed (2R) scheme of hydrogen bonds is most favourable for hexagonal form of PANBLA. Regarding tetragonal form the above techniques favour a parallel arrangement of 4/1 helices according to right handed 4R model. IR dichroism studies also support the above results. Although the vibrational dynamics of both forms of PAIBLA has been studied, no such study has been performed for PANBLA. In the present communication the vibrational dynamics of PANBLA in tetragonal form (4/1 helix) has been studied through the dispersion of normal modes. The effect of side chain nature on the dynamical behaviour has also been analyzed. Apart from detailed assignments of modes, various characteristic features of dispersion curves have been explained as arising due to internal symmetry in energy momentum space. Finally, the density of states has been used to calculate heat capacity of this polymer.

Structural study on ferroelectric phase transition of vinylidene fluoride-trifluoroethylene random copolymers

Polymer ◽  
1981 ◽  
Vol 22 (10) ◽  
pp. 1312-1314 ◽  
Author(s):  
Kohji Tashiro ◽  
Kohji Takano ◽  
Masamichi Kobayashi ◽  
Yozo Chatani ◽  
Hiroyuki Tadokoro
Keyword(s):  
Phase Transition ◽  
Structural Study ◽  
Ferroelectric Phase Transition ◽  
Vinylidene Fluoride ◽  
Ferroelectric Phase ◽  
Random Copolymers

scholarly journals Synthesis of P(MEO2MA-co-OEGMA) Random Copolymers and Thermally Induced Phase Transition Behaviors in Aqueous Solutions

2015 ◽  
Vol 31 (10) ◽  
pp. 1914-1923
Author(s):  
Yi. GUO ◽  
◽  
Heng-Jiang. LIU ◽  
Jie-Qiong. CHEN ◽  
Ya-Zhuo. SHANG ◽  
...  
Keyword(s):  
Phase Transition ◽  
Aqueous Solutions ◽  
Random Copolymers ◽  
Thermally Induced

Thermoresponsive aggregation behavior of NiPAAm/glyco monomer block copolymers studied by dynamic light scattering

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Zeynep Özyürek ◽  
Brigitte Voit ◽  
Franziska Krahl ◽  
Karl-Friedrich Arndt
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Block Copolymers ◽  
Random Copolymer ◽  
Aggregation Behavior ◽  
Molar Ratio ◽  
Random Copolymers ◽  
Temperature Dependent ◽  
Lcst Behavior ◽  
Monomer Content

AbstractBlock and random copolymers containing N-isopropylacrylamide and (α- D-glucofuranosyl)-6-methacrylamido units were analyzed according to their temperature dependent aggregation behavior. Whereas a 45:55 random copolymer does not exhibit any LCST behavior below 100 °C due to the incorporation of the hydrophilic glyco monomer units, the phase transition could be retained in the physiological range in block copolymers even at a glyco monomer content above 55 mol%. DSL studies revealed that the aggregates of about 50 nm are stabilized above the transition temperature when the glyco monomer block dominates, whereas a glyco block molar ratio of 45% is not sufficient to prevent precipitation of the polymers as evidenced by turbidity measurements. Temperature dependent DLS studies revealed further that below the phase transition temperature an equilibrium between single macromolecules and aggregates is formed.

scholarly journals The II–I Phase Transition Behavior of Butene-1 Copolymers with Hydroxyl Groups

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1315
Author(s):  
Yuanyuan Li ◽  
Tao Li ◽  
Wei Li ◽  
Yahui Lou ◽  
Liyuan Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Design ◽  
Nucleation Density ◽  
Hydroxyl Groups ◽  
Melt Crystallization ◽  
Phase Transition Behavior ◽  
Scanning Calorimetry ◽  
Tetragonal Form ◽  
Stepwise Annealing ◽  
High Incorporation

The crystallization and II–I phase transition of functionalized polybutene-1 with hydroxyl groups were investigated by differential scanning calorimetry. The results show that the incorporated hydroxyl groups increase the nucleation density but decrease the growth rate in melt crystallization. Interestingly, for the generated tetragonal form II, the presence of polar hydroxyl groups can effectively accelerate the phase transition into the thermodynamically stable modification of trigonal form I, especially with stepwise annealing and high incorporation. Using stepwise annealing, II–I phase transition was enhanced by an additional nucleation step performed at a relatively low temperature, and the optimal nucleation temperature to obtain the maximum transition degree was ‒10 °C, which is independent from the content of hydroxyl groups. Furthermore, the accelerating effect of hydroxyl groups on the II–I transition kinetics can be increased by reducing the crystallization temperature when preparing form II crystallites. These results provide a potential molecular design approach for developing polybutene-1 materials.

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