Polymer chai

Modern analytical pyrolysis has conventionally been canied out only by thermal energy to break some covalent bonds in the sample molecules at elevated temperatures to produce smaller and/or volatile fragments (pyrolyzates). On the other hand, the reactive pyrolysis in the presence of organic alkaline, such as tetramethylammonium hydroxide [(CH / NOH] (TMAH) has recently received much attention especially in the field of chai acterizing condensation polymers. 

After brief discussion of the state-of-the-art of modern Py-GC/MS, some most recent applications for stixictural and compositional chai acterization of polymeric materials are described in detail. These include microstixictural studies on sequence distributions of copolymers, stereoregularity and end group chai acterization for various vinyl-type polymers such as polystyrene and polymethyl methacrylate by use of conventional analytical pyrolysis. 

Zhong X, Yuan R, Chai Y, Liu Y, Dai J, Tang D (2005) Glucose biosensor based on self-assembled gold nanoparticles and double-layer 2d-network (3-mercaptopropyl)-trimethoxy-silane polymer onto gold substrate. Sensor Actuator B 104 191-198... 

Solid phase microextraction (SPME) has been shown to be useful for the determination of chloroform in air (Chai and Pawliszyn 1995). This technique is based upon the absorption of chloroform into a polymer coated on a silica liber. Following equilibration of the liber with the atmosphere, chloroform is released via thermal desorption in the injection port of a gas chromatograph. Sample preparation is... 

A recently developed technique, i.e. solid-phase microextraction (SPME), which collects vapors on a micro-liber coated with a gas chromatographic polymer phase (Chai and Pawliszyn, 1995 Grote and Pawliszyn, 1997), may be more promising than typical PSDs for long-term sampling as it permits the entire collected sample to be analyzed. The SPME liber can be exposed directly for rapid assessment of air quality or withdrawn into a tube that controls diffusion to the fiber for longterm sampling. 

Advantage can be taken of this enhanced stability of blends of low molecular polymers by chai n-extending or cross-linking the macromolecules in such mixtures after they have been formed or applied to a substrate. This procedure is the basis of many formulations in the coatings industry. 

Shimomura, M., Utsugi, K., Horikoshi, J., Okuyama, K., Hatozaki, O., and Okuyama, N. Two-Dimensional Ordering of Viologen Polymers Fixed on Chai d Surface of Bilayer Membranes A Peculiar Odd-Even Effect on Redox Potential and Adsorption Spectrum. Langmuir 7, 760 (1991). 

Fu, Y. Yuan, R. Chai, Y. Zhou, L. Zhang, Y., Coupling of a reagentless electrochemical DNA biosensor with conducting polymer film and nanocomposite as matrices for the detection of the HIV DNA sequence, Anal. Lett. 2006, 39, 467 182... 

According to die principles of polycondensation, all of die above reactions will also take place during SSP. The conditions for die latter, however, ai e different as this process is earned out at lower temperatures in a non-homogeneous environment. In order to examine the kinetics of SSP, some assumpdons have to be made to simplify die analysis. These are based on die idea diat die reactive end groups and die catalyst are located in the amoi-phous regions. Polycondensations in die solid state are equilibrium reactions but ai e complicated by die two-phase chai acter of die semiciystalline polymer. 

Polycondensation polymers such as PET are chai acterized by low melt viscosities and low melt sttengdis. Eurthermore, widi PET there is a marked shear liquefaction... 

In Chai-acterization of Higlily Cross-linked Polymers Labana, S., et al. ... 

Chandrasekhar, E, Zay, B.J., Cai, C., Chai, Y., Lawrence, D., 2014. Matched-dual-polymer electrochromic lenses, using new cathodically coloring conducting polymers, with exceptional performance and incorporated into automated sunglasses. J. Appl. Polym. Sci. 131,547-557. 

---