Crystallization Behavior of Poly(3‐hydroxybutyrate) (PHB), Poly(ε‐caprolactone) (PCL) and Their Blend (50:50 wt.%) Studied by 2D FT‐IR Correlation Spectroscopy

Abstract

Summary: Variable-temperature FT-IR spectra of poly(3-hydroxybutyrate) (PHB), poly(e-caprolactone) (PCL) and a PHB/PCL (50:50 wt.%) blend were analyzed by two-dimensional correlation spectroscopy (2DCOS). For this purpose the n(C¼O) region was employed to characterize in some detail the crystallization behavior of the investigated polymer systems during cooling from the melt. The asynchronous 2D correlation spectra clearly captured the existence of three components in the crystallinity-sensitive region of the C¼O stretching mode for PHB and PCL, respectively: a well-ordered, an inter-mediate and a less ordered crystalline state. Furthermore, by 2DCOS application a sequential order of the observed structural changes could be proposed for the whole temperature range during the crystallization of both polymers. In the case of the PHB/PCL (50:50 wt.%) polymer blend, we have split up the spectral data set in the sub-sets between 200-120 8C and 70-30 8C for a more detailed 2DCOS analysis. In this way we could separate the crystallization process of PHB and PCL in the polymer blend.

Two-dimensional correlation spectroscopy in polymer study

“…Various polymer systems, such as block copolymers (Kim et al, 2006b; Jia et al, 2010; Jin et al, 2011), biodegradable polymers (Guo et al, 2011; Unger et al, 2011; Ando et al, 2012; Hoshina et al, 2012, 2014; Wang et al, 2014), conducting polymer (Hong et al, 2005; Grzeszczuk et al, 2013), liquid crystals (Tang et al, 2010; Cheng et al, 2011), polymer blends (Oh et al, 2009; Unger et al, 2009, 2011; Jelèić et al, 2010; Popescu and Vasile, 2010, 2011; Kuo and Liu, 2011), and polymer nanocomposites (Huang et al, 2009; Huang and Kuo, 2010; Peng et al, 2010; Ando et al, 2012; Qu et al, 2012), etc., are analyzed by 2DCOS. Detailed information of polymers for polymerization (Izawa et al, 2001; Hong et al, 2005; Huang and Kuo, 2010; Qu et al, 2012; Noda, 2014d; Seo et al, 2014), melting behavior (Unger et al, 2009; Peng et al, 2010; Popescu and Vasile, 2010), crystallization (Huang et al, 2009; Zheng et al, 2010; Guo et al, 2011; Unger et al, 2011; Ando et al, 2012; Hoshina et al, 2012, 2014; Chai et al, 2013; Wang et al, 2013, 2014), gelation (Wang and Wu, 2011; Su et al, 2012; Park et al, 2013), photoreaction (Lee et al, 2010, 2012), hydration (Lai and Wu, 2013), sorption/desorption processes (Musto et al, 2011; Lai and Wu, 2013; Galizia et al, 2014), and phase transition/separation (Kim et al, 2006b; Cheng et al, 2011; Kuo and Liu, 2011; Hou et al, 2014), etc., which are undergoing under the influence of applied external perturbation, are obtained by 2DCOS. 2DCOS probes with various analytical techniques, such as IR, near-IR (NIR), Raman, X-ray, UV-Vis, THz, NMR spectroscopies, and even chromatography, have been successfully applied in polymer studies.…”

“…In the field of polymer study through 2DCOS, IR spectroscopy is the most commonly used analytical probes. The advantages of 2DCOS, such as the enhanced spectral resolution and determination of sequential changes of spectral band intensities, can provide the useful information in characterizing structural changes of polymer obtained as a function of a perturbation, which is not readily observed in the conventional spectroscopy (Kim et al, 2006b ; Huang et al, 2009 ; Unger et al, 2009 , 2011 ; Del Río et al, 2010 ; Huang and Kuo, 2010 ; Jelèić et al, 2010 ; Jia et al, 2010 ; Lee et al, 2010 , 2012 ; Peng et al, 2010 ; Popescu and Vasile, 2010 , 2011 ; Zheng et al, 2010 ; Cheng et al, 2011 ; Jin et al, 2011 ; Kuo and Liu, 2011 ; Wang and Wu, 2011 ; Zhang et al, 2011 ; Ando et al, 2012 ; Qu et al, 2012 ; Su et al, 2012 ; Wu et al, 2012 ; Chai et al, 2013 ; Lai and Wu, 2013 ; Park et al, 2013 ; Shinzawa et al, 2013 ; Wang et al, 2013 , 2014 ; Hou et al, 2014 ; Noda, 2014c ; Seo et al, 2014 ).…”

“…IR spectroscopy is the most common analytical probes used in 2DCOS (Kim et al, 2006b; Cerdà-Costa et al, 2009; Huang et al, 2009; Unger et al, 2009, 2011; Del Río et al, 2010; Huang and Kuo, 2010; Jelèić et al, 2010; Jia et al, 2010; Lee et al, 2010, 2012; Peng et al, 2010; Popescu and Vasile, 2010, 2011; Zheng et al, 2010; Cheng et al, 2011; Jin et al, 2011; Kuo and Liu, 2011; Musto et al, 2011; Quaroni et al, 2011; Wang and Wu, 2011; Zhang et al, 2011; Ando et al, 2012; Qu et al, 2012; Su et al, 2012; Wu et al, 2012; Chai et al, 2013; Lai and Wu, 2013; Park et al, 2013; Shinzawa et al, 2013; Wang et al, 2013, 2014; Galizia et al, 2014; Hou et al, 2014; Noda, 2014c; Seo et al, 2014). The most popularly applied external perturbation in 2DCOS is temperature (Kim et al, 2006b; Unger et al, 2009, 2011; Jia et al, 2010; Peng et al, 2010; Popescu and Vasile, 2010; Tang et al, 2010; Zheng et al, 2010; Cheng et al, 2011; Wang and Wu, 2011; Pazderka and Kopecký Jr, 2012; Chai et al, 2013; Li et al, 2013; Wang et al, 2013, 2014; Hoshina et al, 2014; Hou et al, 2014; Seo et al, 2014). Applications of 2DCOS in investigations of intriguing properties of polymer system measured by different types of analytical probes has been substantially increased (Izawa et al, 2001; Hong et al, 2005; Kim et al, 2006b; Jiang and Wu, 2008; Huang et al, 2009; Oh et al, 2009; Unger et al, 2009, 2011; Del Río et al, 2010; Huang and Kuo, 2010; Jelèić et al, 2010; Jia et al, 2010; Lee et al, 2010, 2012; Peng et al, 2010; Popescu and Vasile, …”

“…The most popularly applied external perturbation in 2DCOS is temperature (Kim et al, 2006b; Unger et al, 2009, 2011; Jia et al, 2010; Peng et al, 2010; Popescu and Vasile, 2010; Tang et al, 2010; Zheng et al, 2010; Cheng et al, 2011; Wang and Wu, 2011; Pazderka and Kopecký Jr, 2012; Chai et al, 2013; Li et al, 2013; Wang et al, 2013, 2014; Hoshina et al, 2014; Hou et al, 2014; Seo et al, 2014). Applications of 2DCOS in investigations of intriguing properties of polymer system measured by different types of analytical probes has been substantially increased (Izawa et al, 2001; Hong et al, 2005; Kim et al, 2006b; Jiang and Wu, 2008; Huang et al, 2009; Oh et al, 2009; Unger et al, 2009, 2011; Del Río et al, 2010; Huang and Kuo, 2010; Jelèić et al, 2010; Jia et al, 2010; Lee et al, 2010, 2012; Peng et al, 2010; Popescu and Vasile, 2010, 2011; Radice et al, 2010; Tang et al, 2010; Zheng et al, 2010; Cheng et al, 2011; Guo et al, 2011; Jin et al, 2011; Kuo and Liu, 2011; Ma et al, 2011; Wang and Wu, 2011; Zhang et al, 2011; Ando et al, 2012; Hoshina et al, 2012, 2014; Qu et al, 2012; Su et al, 2012; Wu et al, 2012; Zhong et al, 2012; Chai et al, 2013; Grzeszczuk et al, 2013; Lai and Wu, 2013; Park et al, 2013; Shinzawa et al, 2013; Wang et al, 2013, 2014; Hou et al, 2014; Noda, 2014c,d; Seo et al, 2014). Generalized 2D correlation spectra has notable advantages: examination of inter- or intra-molecular interactions and determination of the sequential order of events, which is hardly depicted in conventional spectroscopy.…”

“…The generalized 2DCOS can elucidate information in spectral variations, e.g., IR (Kim et al, 2006b ; Cerdà-Costa et al, 2009 ; Huang et al, 2009 ; Unger et al, 2009 , 2011 ; Del Río et al, 2010 ; Huang and Kuo, 2010 ; Jelèić et al, 2010 ; Jia et al, 2010 ; Lee et al, 2010 , 2012 ; Peng et al, 2010 ; Popescu and Vasile, 2010 , 2011 ; Zheng et al, 2010 ; Cheng et al, 2011 ; Jin et al, 2011 ; Kuo and Liu, 2011 ; Musto et al, 2011 ; Quaroni et al, 2011 ; Wang and Wu, 2011 ; Zhang et al, 2011 ; Ando et al, 2012 ; Qu et al, 2012 ; Su et al, 2012 ; Wu et al, 2012 ; Chai et al, 2013 ; Lai and Wu, 2013 ; Park et al, 2013 ; Shinzawa et al, 2013 ; Wang et al, 2013 , 2014 ; Galizia et al, 2014 ; Hou et al, 2014 ; Noda, 2014c ; Seo et al, 2014 ), Raman (Radice et al, 2010 ; Tang et al, 2010 ; Ma et al, 2011 ; Ji et al, 2012 ; Pazderka and Kopecký Jr, 2012 ; Brewster et al, 2013 ; Grzeszczuk et al, 2013 ; Noda, 2014d ), terahertz (THz) (Hoshina et al, 2012 , 2014 ), X-ray (Guo et al, 2011 ), UV-Vis (Hong et al, 2005 ; Jiang and Wu, 2008 ; Sikirzhytski et al, 2012 ; Zhong et al, 2012 ), NMR (Oh et al, 2009 ; Li et al, 2013 ), fluorescence (Hur et al, 2011 ; Zhang et al, 2013 ), and even chromatography (Izawa et al, 2001 ), under various external perturbations, such as thermal, electrical, optical, magnetic, and chemical perturbations (Noda, 1986 , …”