Phase transitions polymers

We begin our application of thermodynamics to polymer phase transitions by considering the fusion (subscript f) process crystal -> liquid. 

Melting-point temperature Decomposition temperature Boiling-point temperature Crystalline particles or polymers Phase transition Shape of crystal Shock sensitivity Friction sensitivity... 

PHASE FIELD MODELING ON POLYMER PHASE TRANSITIONS... 

Polymer Phase transitions Polymer Phase transitions... 

These PNIPAM colloids self-assemble in deionized water to form CCA both above and below the polymer phase transition temperature. The ordered array diffracts light almost following Bragg s diffraction law (but not exactly as shown elsewhere ( ) ) ... 

Characterization of Monomers and Polymers. Phase transitions of monomers were determined by means of Differential Scanning Caloimetry (DSC) using the Perkin Elmer Dl C IB and thermal polarizing microscopy. 

Keller, A. and S.Z.D. Cheng. 1998. The role of metastability in polymer phase transitions. Polymer 39 4461. 

The interplay of polymer phase transitions has been extensively studied in solutions, dated back to Richards in 1946 (Richards 1946). Flory s classical book in 1953 introduced the complete set of phase diagrams (Flory 1953). Recently, Cheng comprehensively reviewed the experimental progress on the interplay of polymer phase transitions (Cheng 2008). Keller emphasized in a review paper that, in the preparation of the thermoreversible gel, crystallization can freeze the gel structure generated by the prior continuous phase separation (Keller 1995). A practical example of such interplay of phase transitions is in the production of... 

Polymers can be tested by means of IGC technique. The following parameters and phenomena can be determined or investigated molecular masses of polymers, phase transitions, glass transition temperatures, kinetics of reaction with polymers, values of thermodynamic functions of dissolution of different substances in polymers, and acidic/ basic properties of polymers. 

Polymer phase transitions are traditionally probed by exploiting the temperature dependence of x to induce segregation. The location of the transition can be readily changed by adjusting the component volume fractions, ( > or N. Recently the effects of liquid organic solvents , homopolymer diluents and pressure have been studied in efforts to assess the phase behavior of blends and copolymers under realistic processing conditions. 

Kozlovsky, M. V., and Bere.snev, L. A., Ferroelectric liquid crystalline polymers, Phase Transitions, 40, 129-169 (1992). 

Although SFM is traditionally an intrinsically slow imaging technique, a wealth of growth rate data has been obtained on the lamellar level. Furthermore, recent developments in the area of high speed SPM (289-291) show that realtime SFM at elevated temperatures possesses the potential to develop into an indispensable microscopic tool for the quantitative investigation of polymer phase transitions and other processes at elevated temperatures and as such may help to develop better theories of, eg, polsrmer ciystallization. 

Protein Folding Modeled by a Two-State Polymer Phase Transition... 

The concept of using responsive polymer phase transitions to switch binding interactions with DNA was first explored by Hennink and co-workers, who showed that a cationic polymer of N,N (2-dimethylamino)-ethyhnethacrylate (DMAEMA) and related copolymers were able to bind and transfect DNA effectively. Copolymerisation of DMAEMA with NIP Am yielded polymers that complexed with DNA at room temperatore but did not exhibit variations of binding with polymer LCST response. This group observed that low... 

Abstract This chapter describes polymers that undergo a temperature-induced phase transition in aqueous solution providing an important basis for smart materials. Different types of temperature-responsive polymers, including shape-memory materials, hquid crystalline materials and responsive polymer solutions are briefly introduced. Subsequently this chapter will focus on thermoresponsive polymer solutions. At first, the basic principles of the upper and lower critical temperature polymer phase transitions will be discussed, followed by an overview and discussion of important aspects of various key types of such temperature-responsive polymers. Finally, selected potential apphcations of thermoresponsive polymer solutions will be described. 

Most interesting, however, are thermoresponsive polymer phase transitions in aqueous solutions since this phenomenon provides high potential for biomedical applications, such as drug dehvery and switchable synthetic cell culture surfaces (de las Heras Alarcon et al, 2005 Schmaljohann, 2006 Ward and Theoni, 2011). The remainder of this chapter will focus on such temperature-responsive polymers in aqueous solution, by discussing basic principles (Section 2.2) and key types of temperature-responsive polymers (Section 2.3) as well as selected applications (Section 2.4). 

The change in polymer conformation during the LCST transition can also be applied to control the proximity of side-chain functionalities. In a recent report, this characteristic of the polymer phase transition was exploited to control the binding kinetics of mannose-functionalized PNIPAM hydrogel... 

Schematic representation of the concept of polymeric sensors based on a polymer phase transition as thermoresponsive structure and solvatochromic dyes to provide a visual or fluorescence read-out signal of the change in the polarity of the microenvironment (Pietsch et a ., 2011). (Source Reprinted with permission from the RSC.)... 

Pietsch, C., Schubert, U. S. and Hoogenboom, R. (2011) Aqueous polymeric sensors based on temperature-induced polymer phase transitions and solvatochromic dyes, Chem Commun, 47,8750-8765, doi 10.1039/C1CC11940K. 

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