Heat Capacities and Phase Separation Behavior of Amphipathic Synthetic Polymer Poly(2-(2-ethoxy)ethoxyethyl vinyl ether)

Heat capacities of amphipathic synthetic polymer poly(2-(2-ethoxy)ethoxyethyl vinyl ether) (PEVE) solutions with 9.4, 15.8, 21.1, and 40.4wt% were measured by adiabatic calorimetry. All the PEVE solutions exhibited heat capacity steps due to glass transition around 200 K, large heat capacity peaks due to fusion of water around 273 K, and heat capacity peaks due to phase separation around 314 K. From the observed enthalpy of fusion of water, the amount of unfrozen water was estimated to be 6.2 mol per repeat unit of PEVE. Theoretical excess heat capacity curves calculated in terms of extended Barker-Henderson theory reproduced experimental excess heat capacities around the phase separation temperatures roughly.

(by Y. Miyazaki)

	Fig. 1. Repeat unit of PEVE.		Fig. 2. Heat capacities of PEVE solutions per mole of repeat unit of PEVE. ○: 9.4wt%, △: 15.8wt%, ☐: 21.1wt%, ▽: 40.4wt%, ●: dried sample. Inset shows heat capacities around phase separation temperatures.
	Fig. 3. Excess heat capacities of PEVE solutions with 9.4, 21.1 and 40.4wt%. Thick solid curves are theoretical excess heat capacities, which reproduce experimental ones roughly.

Heat Capacities and Glass Transitions of the Biodegradable Synthetic Polymer Poly(Lactic Acid)

Calorimetry of the biodegradable synthetic polymer poly(lactic acid) (PLA) were performed by differential scanning and adiabatic calorimetries. Both DSC signals of as-received and liquid-quenched samples showed glass transitions around 60 °C, cold crystallizations around 100 °C, and fusions around 175 °C. On the other hand, DSC signal of annealed sample around 140 °C exhibited only a fusion around 175 °C. Heat capacities of both as-received and liquid-quenched samples indicated large heat capacity jumps around 320 K and remarkable exothermic effects due to cold crystallizations above 330 K, while heat capacity of annealed sample gave rise to only a small heat capacity jump due to glass transition. Below 70 K, so-called low-energy excitation due to glass was observed, in which the heat capacity of the glassy state became larger than that of the crystalline state. However, the heat capacity of the crystalline state became larger than that of the glassy state between 70 and 200 K against the usual phenomenon.

(by Y. Miyazaki)

	Fig. 1. Repeat unit of PLA.		Fig. 2. DSC thermogram for PLA.
	Fig. 3. Heat capacities of PLA per mole of repeat unit of PLA. ◎: As-received sample, ○: liquid-quenched sample, ●: annealed sample. All the samples exhibited glass transitions around 320 K.
	Fig. 4. Heat capacity differences between glassy and crystalline states of PLA. Solid curve represents heat capacity difference between the contributions of the skeletal vibrations for glassy and crystalline states of PLA.

Heat Capacity and Helix Reversal of the Synthetic Polymer Poly{3-[(S)-2-methylbutoxy]phenyl isocyanate} in Tetrahydrofuran

Heat capacities of the synthetic polymer poly{3-[(S)-2-methylbutoxy]phenyl isocyanate} (PPIC) and its tetrahydrofuran (THF) solution with 7.560wt% of concentration were measured by adiabatic calorimetry. Bulk sample exhibited two broad heat capacity peaks due to transitions around 210 and 250 K, while THF solution sample showed a broad heat capacity peak due to transition around 210 K together with a sharp heat capacity peak due to fusion of THF at 164.5 K. From the observed enthalpy of fusion of THF, the amount of unfrozen THF was estimated to be 1.3 mol per repeat unit of PPIC. The change of sign of CD signal in the THF solution sample seems to correspond not to the heat capacity peak temperature of the THF solution sample but to the higher heat capacity peak temperature of the bulk sample.

(by Y. Miyazaki)

	Fig. 1. Repeat unit of PPIC.
	Fig. 2. Heat capacities of THF solution of PPIC with 7.560wt% of concentration and bulk PPIC per mole of repeat unit of PPIC. ○, ●: THF solution sample, ◎: bulk sample. Two broad peaks due to transitions were observed around 210 and 250 K for the bulk sample. The THF solution sample exhibited only a sharp peak due to fusion of THF at 164.5 K.
	Fig. 3. (a) Apparent heat capacities of PPIC in THF solution. A broad peak due to transition were found around 210 K. (b) CD signals of THF and dichloromethane solution samples. ○: THF solution sample, ●: dichloromethane solution sample.

Calorimetry of a Single Larva of Artemia

Isothermal miocrocalorimeter was modified to measure slow and weak thermal dissipation for developmental biology. Post-dormant development of a single larva of Artemia franciscana (Great Salt Lake) was measured as a function of incubation time at T=293.17 K. Characteristic thermal dissipations were observed at emergence, hatching and every molting.

(by Y. Nagnano)

	Photo 1. Prenauplius larva of Artemia in umbrella state.		Photo 2. Nauplius larva of Artemia at the second stage.
	Fig. 1. Thermal dissipation of a nauplius larva of Artemia.