Understanding the Synthesis of Linear–Bottlebrush–Linear Block Copolymers: Toward Plastomers with Well-Defined Mechanical Properties

2020 ◽  
Vol 53 (19) ◽  
pp. 8324-8332 ◽  
Author(s):  
Yidan Cong ◽  
Mohammad Vatankhah-Varnosfaderani ◽  
Vahid Karimkhani ◽  
Andrew N. Keith ◽  
Frank A. Leibfarth ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Block Copolymers ◽  
Linear Block

Structural and mechanical properties of new block copolymers designed for biomedical use

Polymer ◽  
1977 ◽  
Vol 18 (4) ◽  
pp. 387-390 ◽  
Author(s):  
P. Ferruti ◽  
E. Martuscelli ◽  
L. Nicolais ◽  
M. Palma ◽  
F. Riva
Keyword(s):  
Mechanical Properties ◽  
Block Copolymers

Processes for obtaining linear block copolymers

2007 ◽  
Vol 76 (8) ◽  
pp. 731-765 ◽  
Author(s):  
Tat'yana B Zheltonozhskaya ◽  
Sergei V Fedorchuk ◽  
Vladimir G Syromyatnikov
Keyword(s):  
Block Copolymers ◽  
Linear Block

Effect of Block Molecular Weight on the Mechanical Properties of PA1010-b-PEG Segmented Block Copolymers

2012 ◽  
Vol 512-515 ◽  
pp. 2127-2130
Author(s):  
Li Huo ◽  
Cai Xia Dong
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Block Copolymers ◽  
Microphase Separation ◽  
Soft Segment ◽  
Mechanical Measurements ◽  
Wide Range ◽  
Hard Block ◽  
Higher Temperature ◽  
Hard Segments

The mechanical properties were investigated of a series of PA-PEG thermalplastic elastomer based on PA1010 and polytetramethylene glycol (PEG) with varying hard and soft segment content. Dynamic mechanical measurements of these polymers have carried out over a wide range of temperatures. The block copolymers exhibit three peaks, designated as α, β and γ in the tanδ-temperature curve. The α transition shifts to higher temperature with increasing hard block molecular weight. However, at a constant hard molecular weight, the α transition shifts to higher temperature and the damping increases on increasing the soft segment molecular weight. DMA results show that the block copolymers exhibit a microphase separation structure and both soft and hard segments were found to be crystallizable. The degree of phase separation increases with increasing hard block molecular weight.

scholarly journals Influence of Uncoupled Diblock Molecules on Mechanical Properties of Styerene/Butadiene/ Styrene Triblock Copolymers

2012 ◽  
Vol 12 ◽  
pp. 149-156 ◽  
Author(s):  
Rameshwar Adhikari
Keyword(s):  
Mechanical Properties ◽  
Block Copolymers ◽  
Tensile Deformation ◽  
Triblock Copolymers ◽  
Large Strain ◽  
Deformation Behaviour ◽  
Mechanical Analysis ◽  
Transmission Electron ◽  
Star Block Copolymers ◽  
Butadiene Styrene

The influence of the presence of uncoupled polystyrene-block-polybutadiene (SB) diblock chains to polystyrene-block-polybutadiene-block-polystyrene (SBS) triblock copolymers on the mechanical properties of the latter has been studied by means of tensile testing and dynamic mechanical analysis preparing several lamellae forming SBS/ SB blends through solution casting. The microphase-separated morphology of the samples was investigated by transmission electron microscopy. Both large strain deformation tensile deformation behaviour and viscoelastic properties of the SBS block copolymers were found to be affected appreciably by the presence of uncoupled SB diblock. The storage modulus of linear SBS was found to drop more sharply in the plateau region than for the radial SBS at the same SB content. At low SB content (up to 20 wt.-% for linear SBS and still higher for radial one), the overall tensile properties was not negatively influenced. On the whole, star block copolymers were found to be less sensitive towards the presence of diblock.DOI: http://dx.doi.org/10.3126/njst.v12i0.6493 Nepal Journal of Science and Technology 12 (2011) 149-156

Rheology of Block Copolymers

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Block Copolymers ◽  
Small Angle ◽  
Volume Fraction ◽  
Synthesis Methods ◽  
Chemical Structures ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Molecular Weight Form

Block copolymer consists of two or more long blocks with dissimilar chemical structures which are chemically connected. There are different architectures of block copolymers, namely, AB-type diblock, ABA-type triblock, ABC-type triblock, and AmBn radial or star-shaped block copolymers, as shown schematically in Figure 8.1. The majority of block copolymers has long been synthesized by sequential anionic polymerization, which gives rise to narrow molecular weight distribution, although other synthesis methods (e.g., cationic polymerization, atom transfer radical polymerization) have also been developed in the more recent past. Owing to immiscibility between the constituent blocks, block copolymers above a certain threshold molecular weight form microdomains (10–50 nm in size), the structure of which depends primarily on block composition (or block length ratio). The presence of microdomains confers unique mechanical properties to block copolymers. There are many papers that have dealt with the synthesis and physical/mechanical properties of block copolymers, too many to cite them all here. There are monographs describing the synthesis and physical properties of block copolymers (Aggarwal 1970; Burke and Weiss 1973; Hamley 1998; Holden et al. 1996; Hsieh and Quirk 1996; Noshay and McGrath 1977). Figure 8.2 shows schematically four types of equilibrium microdomain structures observed in block copolymers. Referring to Figure 8.2, it is well established (Helfand and Wasserman 1982; Leibler 1980) that in microphase-separated block copolymers, spherical microdomains are observed when the volume fraction f of one of the blocks is less than approximately 0.15, hexagonally packed cylindrical microdomains are observed when the value of f is between approximately 0.15 and 0.44, and lamellar microdomains are observed when the value of f is between approximately 0.44 and 0.50. Some investigators have observed ordered bicontinuous double-diamonds (OBDD) (Thomas et al. 1986; Hasegawa et al. 1987) or bicontinuous gyroids (Hajduk et al. 1994) at a very narrow range of f (say, between approximately 0.35 and 0.40) for certain block copolymers. Figure 8.2 shows only one half of the symmetricity about f = 0.5. Transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) have long been used to investigate the types of microdomain structures in block copolymers.

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