Recent Developments in Synthesis of Model Block Copolymers Using Ionic Polymerisation

2004 ◽  
pp. 31-69 ◽  
Author(s):  
Kristoffer Almdal
Keyword(s):  
Block Copolymers ◽  
Model Block ◽  
Recent Developments

The synthesis of model block copolymers of Poly(cis-1,4-isoprene : styrene)

1968 ◽  
Vol 21 (7) ◽  
pp. 1835 ◽  
Author(s):  
DN Cramond ◽  
JR Urwin
Keyword(s):  
Block Copolymers ◽  
Molecular Size ◽  
Model Block

The synthesis of model block copolymers of poly(cis-1,4-isoprene : styrene)initiated by butyllithium in the solvent benzene is described in detail, and the analysis of the microstructure of the polyisoprene sequence discussed. The copolymers were found to be of narrow distribution in molecular size and composition and the microstructure was close to that expected from previously published results on the synthesis of polyisoprenes.

Model block copolymers with complex architecture

1998 ◽  
Vol 132 (1) ◽  
pp. 207-220 ◽  
Author(s):  
Nikos Hadjichristidis ◽  
Yiannis Poulos ◽  
Apostolus Avgeropoulos
Keyword(s):  
Block Copolymers ◽  
Model Block ◽  
Complex Architecture

Recent developments in biodegradable block copolymers

2021 ◽  
Author(s):  
Sunil U. Tekale ◽  
Yakir Rottenberg ◽  
Rajita D. Ingle ◽  
Abraham J. Domb ◽  
Rajendra P. Pawar
Keyword(s):  
Block Copolymers ◽  
Recent Developments

scholarly journals The Mechanism of the Helix-Sense Inversion of Polyaspartates as Revealed by the Study of Model Block Copolymers

2002 ◽  
Vol 34 (6) ◽  
pp. 450-454 ◽  
Author(s):  
Akinobu Ushiyama ◽  
Hidemine Furuya ◽  
Akihiro Abe ◽  
Toshimasa Yamazaki
Keyword(s):  
Block Copolymers ◽  
Model Block

scholarly journals Recent Developments in the Crystallization of PLLA-Based Blends, Block Copolymers, and Nanocomposites

2021 ◽  
Author(s):  
Amit Kumar Pandey ◽  
Shinichi Sakurai
Keyword(s):  
Block Copolymers ◽  
Liquid State ◽  
Triblock Copolymers ◽  
Nucleating Agent ◽  
The Third ◽  
Confined Crystallization ◽  
The Poor ◽  
The Matrix ◽  
Recent Developments ◽  
Poly Ethylene

Despite the extensive studies of poly(L-lactic acid)(PLLA), the crystallization of PLLA-based materials is still not completely understood. This chapter presents recent developments of crystallization of PLLA-based blends, block copolymers and nanocomposites. The first section of the chapter discusses the acceleration of PLLA crystallization by the inclusion of biobased (solid and liquid state) additives. It was found that the solid state additives work as a nucleating agent while the liquid-state additive works as a plasticizer. Both type of the additives can significantly enhance the crystallization of PLLA, as indicated by crystallization half-time (t0.5) values. Such composites are of great interest as they are 100% based on renewable resources. The second section talks about the enhanced formation of stereocomplex (SC) crystals in the PLLA/PDLA (50/50) blends by adding 1% SFN. It was found that the loading of SFN enhances the formation of SC crystals and it suppresses the formation of HC (homocrystal). The third section deals with confined crystallization of poly(ethylene glycol) (PEG) in a PLLA/PEG blend. The PLLA/PEG (50/50) blend specimen was heated up to 180.0°C and kept at this temperature for 5 min. Then, a two-step temperature-jump was conducted as 180.0°C → 127.0°C → 45.0°C. For this particular condition, it was found that PEG can crystallize only in the preformed spherulites of PLLA, as no crystallization of PEG was found in the matrix of the mixed PLLA/PEG amorphous phase. The last section describes the confined crystallization of PCL in the diblock and triblock copolymers of PLA-PCL. Furthermore, enantiomeric blends of PLLA-PCL and PDLA-PCL or PLLA-PCL-PLLA and PDLA-PCL-PDLA have been examined for the purpose of the improvement of the poor mechanical property of PLLA to which the SC formation of PLLA with PDLA components are relevant.

Block Copolymers, Polymer-Polymer Interfaces, and the Theory of Inhomogeneous Polymers

1976 ◽  
Vol 49 (2) ◽  
pp. 237-246 ◽  
Author(s):  
E. Helfand
Keyword(s):  
Block Copolymers ◽  
Polymeric Materials ◽  
Point Of View ◽  
Polymer Interfaces ◽  
Surface Layers ◽  
Crystalline Materials ◽  
Immiscible Polymers ◽  
Recent Developments ◽  
Physical Features ◽  
Insight Into

Abstract Most of the polymeric materials one encounters so widely are heterogeneous. For instance, commercial plastics may be blends of immiscible polymers; they may contain antioxidants or other modifiers which are not totally soluble; andfrequently they have added inorganic fillers. Other examples of inhomogeneity in polymer systems are composites, partially crystalline materials, surface layers, ionomers, and block and graft copolymers. In some cases the heterogeneity is the essence of the material's virtue (e.g., its mechanical properties). In other cases heterogeneity is an affliction. But, whether one's goal is to maximize or minimize the effect of nonuniformity, it is well to understand the factors which determine the features of inhomogeneous polymers. This we will attempt to do in a qualitative way by describing, from a simple molecular point of view, the entropy and energy terms which control the systems' physical features. Rather than dealing in generalities, however, let us focus on two particular cases : interfaces between immiscible polymers, and block copolymers. This should provide the reader with some insight into the myriad of recent developments in the field of polymer blends, composites, and microheterogeneities.

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